Studio diagnostico-analitico sul dipinto “Gioconda con colonne”
10.6092/issn.1973-9494/4178
SummaryThe painting “Gioconda with columns” from a private collection re-proposes a work of art that is “unique” in the art world, in other words, the “Mona Lisa” by Leonardo da Vinci. The presence of the columns represents the most significant distinguishing feature when compared to the “Mona Lisa” housed in the Louvre.Consequently the question arises: “Is the painting “Gioconda with columns” attributable to the genius of Leonardo or one of his followers or is it to be considered a copy of the “Mona Lisa” in the Louvre or the second “Gioconda” or a copy of the latter?”Thus, the investigation is directed towards identifying the constituent materials and characterizing the pictorial technique in order to artistically collocate its execution and contribute to providing a reliable answer based on both a subjective and objective evaluation.For this purpose, the study was conducted with the cooperation of an art historian and restorer, as well as a physicist and a technical diagnostician, thus integrating competences that were able to lead to the final results. RiassuntoIl dipinto “Gioconda con colonne” di collezione privata ripropone un’opera d’arte “unicum” nel mondo dell’arte, ovvero “Monna Lisa-Gioconda” di Leonardo da Vinci. La presenza delle colonne rappresenta l’aspetto distintivo più significativo rispetto a “La Gioconda” conservata al Louvre.Sorge di conseguenza la domanda: «Il dipinto “Gioconda con colonne” è da ricondurre al genio Leonardesco o ad un suo seguace, o è da considerare una copia de “La Gioconda” conservata al Louvre o la seconda “Gioconda” o una copia di quest’ultima?»L’indagine è quindi rivolta all’identificazione dei materiali costituenti e alla caratterizzazione della tecnica pittorica con lo scopo di collocare artisticamente l’esecuzione e contribuire a fornire una risposta affidabile sulla base di una valutazione sia soggettiva che oggettiva.A tal riguardo lo studio è stato condotto con il concorso dello storico dell’arte, del restauratore oltre che fisico e del tecnico-diagnosta, in una integrazione di competenze che hanno potuto condurre ad una risultanza finale. RésuméLe tableau « Joconde aux colonnes », provenant d’une collection privée, propose encore une fois une œuvre qui est un « unicum » dans le monde de l’art, à savoir « Mona Lisa/Joconde » de Léonard de Vinci. La présence des colonnes est l’aspect le plus significatif qui le distingue de « La Joconde » conservée au Louvre.La question qui se pose est alors la suivante : « Le tableau “La Jocondeaux colonnes” est-il dû au génie de Léonard ou à celui de l’un de ses disciples, ou doit-on le considérer comme une copie de “La Joconde” conservée au Louvre, ou comme la deuxième “Joconde”, ou comme une copie de cette dernière ? »L’investigation est donc axée sur l’identification des matériaux utilisés et sur la caractérisation de la technique picturale, afin de situer l’exécution au niveau artistique et de contribuer à fournir une réponse fiable, d’après une évaluation tant subjective qu’objective.Dans ce cadre, l’étude a été conduite avec le concours de l’historien de l’art, du restaurateur, du physicien et du technicien diagnostiqueur, dans une intégration des compétences qui a pu conduire à des conclusions finales. ZusammenfassungDas aus einer Privatsammlung stammende Gemälde “Gioconda con colonne” (etwa: Mona Lisa mit Säulen)  erinnert an ein Kunstwerk, das in der Welt der Kunst ein „Unikum“ darstellt, das heißt die “Mona Lisa“ von  Leonardo da Vinci.  Das Vorhandensein der Säulen bildet das bedeutsamste Unterscheidungsmerkmal gegenüber der im Louvre verwahrten „Mona Lisa“.Daraus ergibt sich die Frage: «Ist das Gemälde “Gioconda con colonne” dem Genie Leonardos oder einem seiner Schüler zuzuschreiben, oder ist es als Kopie der im Louvre verwahrten „Mona Lisa“, als zweite „Mona Lisa“ oder als Kopie dieser letzteren zu betrachten?»Die Untersuchung gründet sich hier auf die Identifizierung der verwendeten Materialien und der Maltechnik, um die Ausführung künstlerisch einstufen und eine zuverlässige Antwort auf der Grundlage sowohl einer subjektiven als auch einer objektiven Beurteilung geben zu können.Diesbezüglich wurde die Studie mit Unterstützung von Kunsthistorikern, Restaurateuren sowie Physikern und technischen Diagnostikern betrieben, wodurch die Integration von Fachkompetenzen zustande kam, die schließlich zu einem Endergebnis geführt hat. ResumenLa pintura "Gioconda con columnas" de una colección privada vuelve a proponer una obra de arte única en el mundo del arte, es decir "Mona Lisa-Gioconda" de Leonardo da Vinci. La presencia de las columnas representa la característica distintiva más significativa respecto a "La Gioconda" conservada en el Louvre.Como consecuencia surge una pregunta: «¿La pintura "Gioconda con columnas" ha de ser reconducida al genio de Leonardo o a uno de sus secuaces, o ha de ser considerada una copia de "La Gioconda" conservada en el Louvre, la segunda "Gioconda" o una copia de la última?».Por tanto, la investigación está orientada a identificar los materiales constitutivos y a delinear el carácter de la técnica pictórica con el objetivo de colocar artísticamente su ejecución y dar una contribución para brindar una respuesta fiable basada en una valoración tanto subjetiva como objetiva.Por ello el estudio ha sido realizado con la colaboración de un historiador de arte, de un restaurador, además de un físico y de un técnico-diagnóstico, quienes han reunido las competencias que han permitido llevar a un resultado final. РезюмеКартина «Джоконда с колоннами» из частной коллекции повторяет уникальное произведение исскуства, то есть  «Мона Лизу – Джоконду»  Леонардо да Винчи. Присутствие колонн является наиболее значительным элементом, отличающим ее от «Джоконды», находящейся в Лувре. Возникает как следствие этого вопрос: присваивать ли картину «Джоконда с колоннами» гениальности Леонардо или его приемнику или считать ее копией «Джоконды», хранящейся в Лувре, или это вторая «Джоконда» Леонардо или копия второй «Джоконды»?Исследование, следовательно, обращено на идентификацию составляющих материалов и характеристику техники живописи с целью художественного размещения исполнения и для обеспечения надежного ответа на основе  субъективной и объективной оценки.В связи с этим, исследование было проведено при содействии историка искусства, реставратора, а также физика и техника-диагноста, при интеграции компетенций, которые смогли привести к окончательному результату. 摘要 “Gioconda con colonne(带圆柱的蒙娜丽莎)”这幅私人珍藏画再次呈现了艺术世界独一无二的珍品，即列奥纳多达芬奇的“蒙娜丽莎”。画里的圆柱代表与卢浮宫“蒙娜丽莎”最明显的区分因素。因此出现了这个问题: «“Gioconda con colonne(带圆柱的蒙娜丽莎)”这幅画是由天才达芬奇或他的追随者画的，或者是卢浮宫“蒙娜丽莎”的模仿画，又或者是第二个“蒙娜丽莎”还是第二个“蒙娜丽莎”的模仿画?»这种研究针对画家使用的材料和画画技巧的特征而确定作画者的风格，通过一种主观和客观的分析提供了一个可靠的答案。其实上述研究是在艺术史学家、文物修复学家、物理学家和技术诊断学家的协助下进行的，在他们的共同合作下得到了最终结果。 
application/pdf
1973-9494
4178
en
Flavia Fiorillo
Conservation Science in Cultural Heritage
authentication
Diagnostic-analytical study of the painting “Gioconda with columns”
Text.Serial.Journal
https://conservation-science.unibo.it/
13
Articles
2013-12-30
2014-02-06
2013-12-30
2015-11-02
75-102
CSCH
Flavia Fiorillo
2013/12/30
10.6092/issn.1973-9494/4178
75
1973-9494
authentication
en
102
PLAHTER L. E., PLAHTER U. S., 1983, The Young Christ among the Doctors by Teodoer van Baburen, Actaadarchaeologiam et artiumhistoriampertinentia, III
Diagnostic-analytical study of the painting “Gioconda with columns”
https://conservation-science.unibo.it/article/download/4178/3617
13
D    IAGNOSTIC - ANALYTICAL STUDY OF THE PAINTING
     “GIOCONDA WITH COLUMNS”



    Salvatore Lorusso,• Chiara Matteucci, Andrea Natali, Salvatore Andrea
    Apicella, Flavia Fiorillo
    Dipartimento di Beni Culturali
    Alma Mater Studiorum, Università di Bologna



   Keywords: “Gioconda”, “Gioconda with columns”, Leonardo, authentication

    1. Introduction

  The painting “Gioconda with columns” (Figure 1) from a private collection, re-pro-
poses a work of art that is “unique” in the art world, in other words, the “Mona Lisa” by
Leonardo da Vinci.




                                                                                                         CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 1. Photograph in the visible of the painting “Gioconda with columns” Saint Petersburg (oil
on canvas - 85.2x63.2 cm)



• Corresponding author: salvatore.lorusso@unibo.it

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                                                                                                                                               The presence of the columns represents the most significant distinguishing feature
                                                                                                                                           when compared to the “Mona Lisa” housed in the Louvre.
                                                                                                                                               According to Federico Zeri “the work by da Vinci, considered one of the most pres-
                                                                                                                                           tigious of all times, was mutilated, that is, deprived of the two columns that adorned
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                           either side to make a “pendant” for a smaller painting: the lateral framing was there-
                                                                                                                                           fore removed” but is however present in the painting under examination. This view is
                                                                                                                                           shared by Kenneth Clark, Richard Friedenthal and Serge Bramly.
                                                                                                                                               This reduction in size is however refuted by the conservators of the Paris museum:
                                                                                                                                           in 2004 the Louvre version underwent a number of scientific and technical examina-
                                                                                                                                           tions, carried out by a group of 39 international experts.
                                                                                                                                               The above-mentioned investigations also demonstrated that the small portions of
                                                                                                                                           the columns present on the painting were painted over the background of the sky and
                                                                                                                                           the mountains.
                                                                                                                                               Another hypothesis is the existence of a second “Gioconda” by Leonardo da Vinci:
                                                                                                                                           in this second version the columns are present. Experts from the “Mona Lisa Founda-
                                                                                                                                           tion” believe that the matrix of the copies with columns is the Gioconda by Isleworth.
                                                                                                                                               Consequently the question arises: “Is the painting “Gioconda with columns” attribut-
                                                                                                                                           able to the genius of Leonardo or one of his followers or is it to be considered a copy of
                                                                                                                                           the “Mona Lisa” in the Louvre or the second “Gioconda” or a copy of the latter?”
                                                                                                                                               Thus, the investigation is directed towards identifying the constituent materials and
                                                                                                                                           characterizing the pictorial technique in order to artistically collocate its execution and
                                                                                                                                           contribute to providing a reliable answer based on both a subjective and objective
                                                                                                                                           evaluation.
                                                                                                                                               For this purpose, the study was conducted with the cooperation of an art historian
                                                                                                                                           and restorer, as well as a physicist and a technical diagnostician, thus integrating com-
                                                                                                                                           petences that were able to lead to the final results.
                                                                                                                                               The present diagnostic-analytical study was carried out on the painting “Gioconda
                                                                                                                                           with columns”(oil on canvas 85.2x63.2cm) (Figure 1) belonging to a private collection.
                                                                                                                                           The aim of the investigation is to identify the constituent materials and to characterize
                                                                                                                                           the pictorial technique with the purpose of artistically collocating its execution.
                                                                                                                                               Some of the diagnostic-analytical investigations were carried out in the Museum
                                                                                                                                           of St. Petersburg where the painting is conserved and others, on samples taken from
                                                                                                                                           the work, were carried out in the Diagnostic Laboratory for Cultural Heritage of the
                                                                                                                                           Department of Cultural Heritage of the Alma Mater Studiorum University of Bologna
                                                                                                                                           (Ravenna Campus) using both portable and non-portable equipment, in compliance
                                                                                                                                           with principles of innovation and reliability.

                                                                                                                                              The tests include:
                                                                                                                                              -- macroscopic analysis;
                                                                                                                                              -- evaluation of conservation state;
                                                                                                                                              -- characterization of the support;
                                                                                                                                              -- characterization of the binding agent;
                                                                                                                                              -- characterization of the preparation and priming of the support;
                                                                                                                                              -- characterization of the artist’s palette;
                                                                                                                                              -- definition of the painting technique;
                                                                                                                                              -- definition of the sfumato.

                                                                                                                                              For this study the following technologies were applied:


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   -- photography in the visible in diffuse and raking light →photographic camera
Canon 650D(18 MPx), Canon objective 18-35, cold light spotlights(5500⁰K) Lupo, in-
candescent spotlights(500 W), tripod, umbrellas;
   -- microscopy →Zeiss stereoscopicmicroscopeStemis SV11;
   -- reflectography in UV light →multispectral videocameraMusis MS (multispectral
imaging system)(1024x768 px), UV sources Stocker Yale Black Light Blue(365 nm);
   -- reflectography in IR light →multispectral videocameraMusis MS (multispectral
imaging system)(1024x768 px), UV sources Stocker Yale Black Light Blue(365 nm);
   -- image analysis videomicroscopy →Keyence videomicroscope mod.VH5901, ob-
jective (up to 175x);
   -- spectrophotometric colorimetry →spectrophotometric colorimeter Minolta 2600d;
   -- X-ray spectrometry→ Electronic Industry Support spectrometer (38kV, 0.5 mA).

  The following analytical investigations were also carried out:
  -- scanning electronic microscopy with microanalysis of the thin section →SEM In-
spect S FEI with microprobe Edax Phillips New XL-30;
  -- FT IR analysis →FT IR diffractometer Tensor 27 Bruker;
  -- Radiocarbon dating of the support.

  Below are shown the diagnostic-analytical findings that are considered significant in
achieving the set objectives.

  2. Macroscopic analysis

  • Support

   The painting has a support consisting of two canvases mounted on a wooden frame




                                                                                                 CONSERVATION SCIENCE IN CULTURAL HERITAGE
with nails (Figure 2).
   The frame can be extended by means of chocks or angular wedges. It has a hori-
zontal crosspiece in the center of two vertical wooden strips (Figure 3). It is in good
condition and based on the characteristics of its assembly, its fabrication can be traced
back to a period ranging from the late 1800s to the early 1900s[1-2].
   The textile support consists of two canvases glued together (lining).




 Figura 2. Detail of support                 Figura 3. Detail of frame



                                                                                            77
                                                                                                                                              The original borders of the first canvas on which the painting is found are missing
                                                                                                                                           (Figure 4). In fact, along the margins there are no selvages or nail holes from the first
                                                                                                                                           stretching of the work onto the original frame.
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                            Figure 4. Detail of canvas edges            Figure 5. Detail of resinous glue behind
                                                                                                                                                                                        canvas used for lining.

                                                                                                                                              The edges, generally frayed or damaged by nails, were cut and removed when the
                                                                                                                                           painted canvas underwent lining. In this way, any irksome problems at the time of re-
                                                                                                                                           mounting the lined painting onto the new frame, were avoided [3-4].
                                                                                                                                              This practice was common in various parts of Europe among many restorers who
                                                                                                                                           worked between the late 1800s and the 1950s, but possibly even later [4].
                                                                                                                                              The negative aspect of this practice is that it prevents the exact measurements of
                                                                                                                                           the original painting to be determined.
                                                                                                                                              The canvas used to line the painting has the following characteristics: fine threads
                                                                                                                                           and very tight square structured weaving, similar to industrial canvases prepared for
                                                                                                                                           painting. It is therefore believed that the lining was executed with wax.
                                                                                                                                              Originally, the canvas was light-colored, but is now brown as a result of the treat-
                                                                                                                                           ment received during the lining with wax [5].
                                                                                                                                              In fact the brown mixture of wax and colophony (rosin) used in the lining when hot
                                                                                                                                           has impregnated the plant fibers and passed through the woven cloth with ease, as
                                                                                                                                           evidenced by the resinous glue behind the cloth used for the lining (Figure 5).
                                                                                                                                              At present, the two integrated canvases are fitted loosely on the frame.

                                                                                                                                             • Surface of painting

                                                                                                                                               The preparatory layer on which the work is painted is thin and of a color tending
                                                                                                                                           towards a red-brown. The limited thickness of the preparation is such that the weaving
                                                                                                                                           in the cloth is visible on the surface of the painting. It seems that a preparatory white
                                                                                                                                           layer containing white lead is completely missing.
                                                                                                                                               The painting surface has suffered due to the woven cloth below it. The painting is
                                                                                                                                           covered with several layers of resinous paint or other material, such as glue or egg
                                                                                                                                           albumen used as a final varnish.
                                                                                                                                               This represents a serious obstacle to the examination of the conservation state of
                                                                                                                                           the pictorial surface.


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   3. Evaluation of the conservation state and identification of previous conser-
   vation interventions

   Examination of the painting proceeded with the aid of diagnostic instruments.
   The use of photography in raking light and diffuse light, ultraviolet fluorescence
spectrometry and image analysis videomicroscopy allowed an objective evaluation
of the conservation state of the work to be made. They also enabled the identifica-
tion of conservation and restoration interventions that the work has undergone over
time[6].
   Examination of the painting through the use of the aforementioned diagnostic tech-
nologies allowed the following observations to be made:
   -- the work has undergone restoration work on several occasions which has been
discontinuous at times
   -- the painting has undergone a great many re-integrations (of retouching and re-
painting) of various sizes and carried out at different times.

   • Pictorial surface

   The result in raking light in particular (Figure 6) showed the thin layer of paint and
consequently the underlying woven texture of the canvas.
   The most recent cleaning attempts, successively covered with abundant varnish
and coating and identifiable in the UV photo by the brown and black coloring, were
found in the lower right hand part, covering approximately a quarter of the painting’s
surface and small areas along its perimeter at the top (Figure 7).




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A					B

Figure 6. Image using raking light left (A), right (B).



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                                                                                                                                               The images, moreover, highlight the presence of a geometrically selective inter-
                                                                                                                                           vention well-defined by the presence in UV of a vertical line found at the center in the
                                                                                                                                           lower part of the painting. In fact this area gives a different UV fluorescence response
                                                                                                                                           to that of the remainder of the artifact. Two recent repaintings are present on top of the
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                           layer of varnish (in the upper left part and on the woman’s forehead close to the edge
                                                                                                                                           of the veil) and areas of previous retouching – underneath the layer of varnish – in the
                                                                                                                                           area of the cleavage and the sky and landscape on the right of the painting. The use
                                                                                                                                           of videomicroscopy shows that the canvas is not orderly and regular. It also appears
                                                                                                                                           that in correspondence with several areas with cracking, small pieces of paint tend to
                                                                                                                                           come unstuck (Figure 8).




                                                                                                                                           Figure 7. Image using ultraviolet fluorescence.   Figure 8. Videomicroscopy (50x) of the pictorial
                                                                                                                                                                                             paint layer.


                                                                                                                                              • Background

                                                                                                                                               Photography in diffuse light highlights the discontinuity in the sky due to the exces-
                                                                                                                                           sive retouching and cleaning resulting from various interventions (Figure 9).
                                                                                                                                               A great deal of retouching has been done around the head. In the right side of the
                                                                                                                                           sky, behind the nape of the neck there is a sign of very evident retouching almost circu-
                                                                                                                                           lar in shape, of a light blue color tending toward a dark yellow. There are a great many
                                                                                                                                           points that have been retouched in the sky. For this reason many shades of blue are
                                                                                                                                           visible. Furthermore, in this same area, in the upper left part, there are some anoma-
                                                                                                                                           lies, due to a different index of refraction in the surface, probably the result of a final var-
                                                                                                                                           nishing with brushstrokes that have created alternating shiny parts and opaque parts.



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   Figure 9. Detail of background in diffuse light




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Figure 10. Detail of right-hand column in diffuse light



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                                                                                                                                             The landscape is full of retouching. On the right-hand column colors have been
                                                                                                                                           used to produce light effects (Figure 10).

                                                                                                                                             • Figure
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                              Diffused light technology reveals, on the other hand, that the outline of the figure
                                                                                                                                           (head and shoulders) is marked by a strong, dark and clear sign (Figure 11). Between
                                                                                                                                           the color and the shade of the two flesh tones, in fact, there is a difference: the hands
                                                                                                                                           are more rosy and soft compared to the rest that has few chromatic vibrations. The
                                                                                                                                           hands, moreover, have some very small points which have been retouched and some
                                                                                                                                           tiny dark spots (Figure 12).




                                                                                                                                                                   Figure 11. Detail of the figure in diffuse light




                                                                                                                                                                   Figure 12. Detail of the hands in diffuse light




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Figure 13. Videomicroscopy image of the flesh tones




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     Figure 14. Detail of the figure in ultraviolet


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                                                                                                                                               Videomicroscopy, moreover, shows the pictorial surface of the flesh tone has very
                                                                                                                                           fine light vertical cracks (Figure 13).
                                                                                                                                               Images produced using ultraviolet (Figure 14) show how the face and neckline have
                                                                                                                                           numerous tiny points that have been retouched. Both the face and neckline have also
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                           undergone cleaning which, however, did not include the hands. Retouching on the
                                                                                                                                           chest follows a direction which goes vertically and to the right and is also vaguely of a
                                                                                                                                           square form. The hair shows significant wear on the right side above the forehead, but
                                                                                                                                           the brown colour hides the degraded parts. Retouching can be seen along the hair that
                                                                                                                                           falls over the left shoulder of the figure.
                                                                                                                                               The curls in the hair that stand out on the flesh color have been damaged by clean-
                                                                                                                                           ing, and either badly and partially redone or retouched. The brown decoration of the
                                                                                                                                           bodice is perfectly painted using great precision. The lights and shadows of the mantle
                                                                                                                                           are not very clear, apart from the light part of the folds higher up, but which are not of
                                                                                                                                           very good quality. Highlights have been added on the sleeves of the dress.

                                                                                                                                              4. Analyses

                                                                                                                                              4.1. Textile support

                                                                                                                                              • Sampling

                                                                                                                                              Sampling of the original support and the subsequent removal of the thick layer of
                                                                                                                                           resin attributable to the lining has allowed the technical characteristics of the canvas
                                                                                                                                           to be highlighted.
                                                                                                                                              As there were no repercussions, sampling was performed on a part of it, that is on
                                                                                                                                           the left side of the painting in correspondence with the left column.

                                                                                                                                              • Diagnostic-analytical investigation and results

                                                                                                                                              The diagnostic-analytical investigations were conducted using technology such as
                                                                                                                                           microscopy and scanning electron microscopy.
                                                                                                                                              Below are the structural characteristicsof the canvas.
                                                                                                                                              The flax fiber is constituted by a bundle of cells with a thick wall, frequently decom-
                                                                                                                                           posed into single units. The characteristics, in particular, are:
                                                                                                                                              Longitudinal appearance: straight fibers with x-shaped transversal dislocations
                                                                                                                                           along the fiber, called nodes (Figure 15).
                                                                                                                                              Cross section: bundle of polygon-shaped cells with a small lumen and thick walls
                                                                                                                                           (Figure 16).
                                                                                                                                              Torsion: Direction of the torsion: in the form of a “Z”.
                                                                                                                                              Frame: woven cloth with alternating weft threads over warp threads (1 weft, 1 warp).
                                                                                                                                              Density: 14 threads per centimeter in the warp and 12 threads per centimeter in the weft.
                                                                                                                                              Microscopic examination of the fiber shows it is constituted by long filaments formed
                                                                                                                                           of bundles of aggregated fibers each with a diameter of between 30 and 40 microns.
                                                                                                                                           These fibers appear gathered together with encrusting substances, wood residues,
                                                                                                                                           partially lignified membranes and various impurities. The individual fibers have a cylin-
                                                                                                                                           drical shape with a thin central channel and ending in a sharp point. Observed longitu-
                                                                                                                                           dinally, the fibers have marked cross-striations that cross each other obliquely to form
                                                                                                                                           an x and have a slight swelling at almost regular intervals.


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                       Figure 15. Flax fiber seen with SEM (1400x)




                                                                                                CONSERVATION SCIENCE IN CULTURAL HERITAGE




            Figure 16. Transversal section of the flax fiber seen with SEM(500x)

   The canvas is therefore realized in flax fiber and has a high average density (Figure
17) suited to the format of the painting. In fact, the choice of the woven clothdecided
by the artists was based on format: closely woven for small sizes, loosely woven, but
stronger for large canvases [7].

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S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                                                                                   Figure 17. Cloth sample observed with SEM

                                                                                                                                               The cloth has irregularities in the weaving due to the closeness of the warp and the
                                                                                                                                           slight variation in the section of the thread.
                                                                                                                                               The fabric has undulations in the threads in the area of the long sides, deformations
                                                                                                                                           due to the tension of the painting on the frame.
                                                                                                                                               The conservation state of the canvas is mediocre. As a result of its complex history
                                                                                                                                           of conservation, the canvas is extremely fragile and worn, with weakening of the fib-
                                                                                                                                           ers and points where it is deteriorated, attributable mainly to the products used in the
                                                                                                                                           lining process.

                                                                                                                                                                                      Atmospheric data from Reimer et al (2009);OxCal v3.10 Bronk Ramsey (2005); cub r:5 sd:12 prob usp[chron]


                                                                                                                                                                             600BP                                           LTL12812A : 280±30BP
                                                                                                                                                                                                                                                                           68.2%probability
                                                                                                                                                 Radiocarbon determination




                                                                                                                                                                                                                                                                            1520AD (38.2%) 1580AD
                                                                                                                                                                             400BP                                                                                          1630AD (30.0%) 1660AD
                                                                                                                                                                                                                                                                           95.4%probability
                                                                                                                                                                                                                                                                            1490AD (93.1%) 1670AD
                                                                                                                                                                             200BP                                                                                          1780AD ( 2.3%) 1800AD


                                                                                                                                                                               0BP


                                                                                                                                                                             -200BP




                                                                                                                                                                                                   1400CalAD                           1600CalAD                           1800CalAD             2000CalAD
                                                                                                                                                                                                                                          Calibrated date

                                                                                                                                                                                                                  Figure 18. Radiocarbon dating


                                                                                                                                      86
   • Radiocarbon dating

    The sample was subjected to radiocarbon dating, that is, the radiocarbon dating
method using high resolution mass spectrometry (AMS).
    The micropollutants in the sample were viewed using an optic microscope and me-
chanically removed.
    Conventional radiocarbon dating was corrected for the effects of isotopic fraction-
ationboth by measuring δ13C value made directly with the accelerator and the base
of the measurement.
    The concentration of radiocarbon was determined by comparing the measured val-
ues of the currents 12C and 13C and the counts of 14C with the values obtained from
standard samples of Saccarose C6 supplied by IAEA (Figure 18).


   4.2.Ground layer

   • Sampling

   The sampling was done on a fragment which included the entire stratigraphy: from
the support to the varnishes. The sampling was carried out on the lower left side of the
painting in correspondence to the left-hand column.
   The preparatory layer is a hidden layer to which little attention is given normally and
for which texts describing painting techniques are vague. It is of great importance how-
ever, especially, for conservation of the work of art. In fact, it is the part of the painting
which is more subject to mechanical stress due to the fact that it is interposed between
two layers with completely different physical characteristics: the flexible layer of the
cloth and the rigid layer of the oil and pigments.
   Even specialist bibliography on the subject is vague and it is difficult to find anything




                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE
specific other than the generic indications covering compositional typologies, except
for a few rare specialist scientific investigations.
   Additional information which is scarce, is in any case contrasting and consequently
denotes only a limited accuracy about a subject which was probably jealously guarded
in workshops external to the artist’s studio itself.

   • Diagnostic-analytical investigation and results

   A description is given of the investigations carried out on cross-sections of samples
embedded in resin (for analysis in scanning electron microscopy) and in potassium
bromide (for analysis in infrared spectroscopy).
   The elemental analyses carried out using scanning electron microscopy (Figure
19-20) identified the presence of the following elements: carbon (C), oxygen (O), alu-
minium (Al), silicon (Si), lead (Pb), calcium (Ca), iron (Fe).
   The following inclusions were also found: sulphur (S), barium (Ba).
   The simultaneous presence of sulphur and barium in the grains lead to assume the
presence of barium sulphate. This is found in the form of disseminated inclusions in
the preparation; the sizes ranging from a few micrometers to dozens of micrometers
demonstrate that it is natural baryte rather than an artificial pigment. If this had been
the case the grain would have had a more regular morphology.


                                                                                                 87
                                                                                                                                              Analysis in Fourier transform infrared spectroscopy revealed the presence of cal-
                                                                                                                                           cium carbonate, aluminosilicates and oil (Figure 21).
                                                                                                                                              The binder in particular was found to be an aged oil since, by means of IR spectros-
                                                                                                                                           copy, the presence of free acid groups were detected (-COO-), whose formation is the
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                           result of hydrolysis of the ester bonds of the triglycerides contained in the drying oils.
                                                                                                                                              Protein binders were not detected.
                                                                                                                                              Before application of the preparatory layer on the canvas, to isolate the fibers and
                                                                                                                                           avoid direct contact with the preparation and to fill the dimensional difference between
                                                                                                                                           the threads, it was a customary procedure to treat the canvas with glue dissolved in
                                                                                                                                           water [8-10].




                                                                                                                                                                           Figure 19. Photograph using electronic microscopy (250x)




                                                                                                                                           Figure 20. EDX spectrum of the preparatory red layer (Energy Dispersive X-ray spectroscopy)


                                                                                                                                               In this case, as no trace of protein binders was found, application of the afore-
                                                                                                                                           mentioned technique was excluded.
                                                                                                                                               The preparatory layer, therefore, is constituted by an organic binder composed of drying
                                                                                                                                           oil, a calcium carbonate-based white component of a white clay type or “bianco di Spag-
                                                                                                                                           na” type, iron aluminosilicate hydrate-based red/brown component of “terra bolare” type
                                                                                                                                           and a lead-based component in the form of oxide (or minium Pb3O4 – red or litharge PbO
                                                                                                                                           yellow-orange), as the presence of ceruse (PbCO3) or hydrocerrusite (Pb3(CO3)2(OH)2).
                                                                                                                                           The presence of barium sulphate (BaSO4) was also found in the form of inclusions.


                                                                                                                                      88
                                                           O




                                                                                        S
                                                                                   S

                                                                               S            S


         O = acids (oil)
         C = carboxylates
         Ca = calcium carbonate
                                                                                   Ca
         S = alumino-silicates

                                                                   Ca


Figure 21. FTIR spectrum of the preparatory layer

   4.3. Primer

   • Diagnostic-analytical investigation and results

    The primer is yellow-brown in color, containing black, white, red and colorless inclu-
sions. It has a thickness of about 40 microns.
    The analytical investigations on the preparatory layer were conducted using scan-
ning electron microscopy and Fourier transform infrared spectroscopy. Below are de-




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE
scribed the investigations performed on the cross-sections of the samples embedded
in the resin (for analysis in scanning electron microscopy) and potassium bromide (for
analyses in infrared spectroscopy).
    The results of the elemental analyses using scanning electron microscope with mi-
croanalysis identified the presence of the following elements (Figure 22): carbon (C),
oxygen (O), iron (Fe), magnesium (Mg), aluminium (Al), silicon (Si), phosphorous (P),
lead (Pb), potassium (K), calcium (Ca).
    The analyses in Fourier transform infrared spectroscopy revealed the presence of
calcium carbonate, aluminosilicate hydrates and oil (Figure 23).
    The presence of the oily binder in particular, was detected thanks to identification of
the ester component of the triglycerides contained in the drying oils.
    In addition, the presence of carboxylates of lead which were formed by the reaction
of a lead-based pigment (Pb3O4 or PbO) with the oily medium.
    The priming therefore, is constituted by an organic binder consisting of drying oil, a
calcium carbonate-based white component of a white clay type or “bianco di Spagna”
type, an iron aluminosilicate hydrate-based brown component and black coal.
    For the purpose of establishing the spatial-temporal collocation of the painting un-
der examination, it is interesting to stop and consider the presence of lead in relation
to the specific formulation of the drying oil used.




                                                                                                89
     S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




90
           Figure 23. FTIR spectrum of the primer
                                                                                Figure 22. EDX spectrum of the primer
    As the color of the primer layer is yellow-brown, the application of the lead in the
form of minium as a pigment (red - Pb3O4) can be excluded in favor of the hypothesis
that it is litharge (yellow-orange – PbO) which is the drying agent in the oil.
    It can therefore be assumed that the drying oil was made such by the addition of
litharge, a practice indicated in a wide range of recipes [11].

   4.4. Pictorial layer

   • Diagnostic-analytical investigation

    Identification of the pigments used by the author to execute the pictorial layer was
carried out by means of x-ray fluorescence spectroscopy.
    X-ray fluorescence spectroscopy allows the elements constituting the artifact, pre-
sent even in traces, to be identified [12].
    As this technology is non-destructive, investigation of the artifact in various points,
was carried out, without any risk of damaging the work of art: it is evident that as
there are a number of pigments present in the painting, it is necessary to repeat the
measurements in different zones to gather any significant data. It must be mentioned
however that the methodology poses several problems owing to the superimposition
of the spectral lines and the fact that the acquired signals refer to several pictorial lay-
ers starting from the surface. Identification of the pigments was carried out through the
reading of the spectral lines that correspond to the main elements.
    Figure 24 shows the points examined.
    The spectra obtained show a series of peaks which correspond to each element
present. This instrumental technique allows the elements of the periodic table from
atomic number 14 up to 92 [12] to be examined. It is also necessary to “purify” the
graphs from the peaks of the elements that are always present, in trace amounts, or




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
that are caused by external interference [12].
    This refers to Ar (argon), present in the air, and to W (tungsten or wolframium) which
is consistently present: this is because part of it is constituted by the instrument itself,
while it is absolutely extraneous to the painting, except in minute quantities. Further-
more, calcium (Ca), iron (Fe), and lead (Pb) are also always present, because they
are fundamental components of the preparation and the primer of the canvas. It is also
necessary to point out that in almost all the paints analyzed varying amounts of copper
(Cu) were found: often small quantities of copper-based pigments (a class of pigments
that give a color from blue to green) are found in the dark shades of almost all colors,
demonstrating the use of these pigments to darken the shade of the color. In addition,
with regard to the flesh colored tones, it is presumed that the addition of small quanti-
ties of copper-based pigments were used by the author to cool down the paint [13-15].
We believe it is appropriate and significant to show in Figure 25 the XRF spectrum
related to point 5 (shaded part of neck).

   • Results

    The following is a description of the results relating to the various selected points
of the painting.




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S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                             Figure 24. Points examined using x-ray fluorescence spectroscopy

                                                                                                                                               ►Light flesh tones
                                                                                                                                               Two areas of the lighter flesh tones must be examined: that of the face and neckline.
                                                                                                                                           In fact a large part of the neckline has undergone major restoration work that has made
                                                                                                                                           it noticeably lighter than the flesh color of the face. In addition, the shadows in the
                                                                                                                                           center have disappeared to the point that the part that has been retouched lacks depth.
                                                                                                                                           The XRF analysis revealed, precisely in the part that has been extensively retouched
                                                                                                                                           the presence of chromium (Cr) and a consistent concentration of lead (Pb).


                                                                                                                                      92
Figure 25. Sample no. 5 shaded part of neck (dark flesh tones)

   The presence of chrome is undoubtedly related to the use of chrome yellow (lead
chromate) in use since the beginning of the 1800s [12, 16-18].
   The investigations carried out on the light flesh tones of the face are compatible




                                                                                                 CONSERVATION SCIENCE IN CULTURAL HERITAGE
with the results of the analysis conducted on the flesh tones of the neckline which have
not been retouched: the color is the result of white and red. The white pigment is lead-
based (Pb), while the red is definitely attributable to iron (Fe). It is deduced that the
pigments used for the light flesh tones are constituted by red earth mixed with white
lead (2PbCO3·Pb(OH)2).
   ►Dark flesh tones
   According to the XRF analyses the dark flesh tones are obtained using an iron-
based pigment (Fe) with percentages of manganese (Mn). Being unable to quantita-
tively estimate the amount of manganese (Mn), it can be assumed that burnt sienna or
burnt umber mixed with white lead was used.
   Traces of copper (Cu) were found in the composition of the flesh tones. The read-
ings of the XRF analyses indicate that more copper (Cu) is found in the dark flesh
tones. This suggests that copper (Cu) was used to create brown pigments also as a
base for the light flesh tones and that to make the flesh tones darker the amount of
copper (Cu) was increased.
   ►Lips
   The red of the lips was obtained with an iron-based pigment (Fe) and presumably a
red earth (ocher) mixed with white lead.
   ►Iris
   The brown of the iris is obtained using an iron-based earth (Fe) with minimum per-
centages of manganese (Mn), diluted with white lead. Consequently, from the XRF

                                                                                            93
                                                                                                                                           analysis high quantities of iron (Fe), lead (Pb) and traces of manganese (Mn) are
                                                                                                                                           evident.
                                                                                                                                              In this case too, a small amount of copper Cu was found, probably used for making
                                                                                                                                           the pigments darker.
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                              ►Pupil
                                                                                                                                                 ►
                                                                                                                                              The pupil above the iris was presumably executed using a carbon-based black
                                                                                                                                           which is not detectable using XRF technique.
                                                                                                                                              ►Sky
                                                                                                                                                 ►
                                                                                                                                              From the XRF analyses the presence of a copper-based pigment is evident in the
                                                                                                                                           color used for the sky. Based on the XRF data alone, it will be necessary to speak
                                                                                                                                           generically of copper-based green pigments, as this is the only heavy element in the
                                                                                                                                           context of the series of antique and modern green and blue pigments. From the analy-
                                                                                                                                           ses it emerged that the copper is not present below the column but on the contrary, in
                                                                                                                                           traces which are substantial at times in the portion represented by the mountains (red-
                                                                                                                                           dish color obtained with Fe and traces of Mn) in the background. It may be assumed
                                                                                                                                           that the column and the sky were painted at different times, while the mountains were
                                                                                                                                           painted directly on the pictorial layer of the sky after it was completed.
                                                                                                                                              The figure of the woman was also probably painted separately, at a different time to
                                                                                                                                           that of the sky and the columns.
                                                                                                                                              ►Hair
                                                                                                                                                 ►
                                                                                                                                              The color of the hair which to the naked eye appears of a reddish brown is obtained
                                                                                                                                           with an iron-based earth (Fe) with minimum amounts of manganese (Mn) diluted with
                                                                                                                                           white lead.
                                                                                                                                              The XRF analyses therefore reveal a high quantity of of iron (Fe) and lead (Pb) and
                                                                                                                                           traces of manganese (Mn).
                                                                                                                                              In this case too, a small amount of copper Cu was found which was probably used
                                                                                                                                           to make the pigments darker.
                                                                                                                                              ►Robe
                                                                                                                                                 ►
                                                                                                                                              The color of the robe was also obtained using an iron-based earth with small per-
                                                                                                                                           centages of manganese (Mn) mixed with white lead. The XRF analysis therefore
                                                                                                                                           showed high quantities of iron (Fe) and lead (Pb) and traces of manganese (Mn).
                                                                                                                                              In this case too, a small quantity of copper Cu was found which was probably used
                                                                                                                                           to make the pigments darker.
                                                                                                                                              ►Sleeve
                                                                                                                                                 ►
                                                                                                                                              The yellow color of the sleeve is obtained thanks to the use of an iron-based pig-
                                                                                                                                           ment (Fe), presumably ocher, diluted with white lead. It is believed that the appreciable
                                                                                                                                           amounts of calcium found, are attributable to the highlighting carried out using a white
                                                                                                                                           - San Giovanni - (calcium carbonate).
                                                                                                                                              ►Low
                                                                                                                                                 ►     wall and floor
                                                                                                                                              In this case too, the browns were obtained using an iron-based earth (Fe) with
                                                                                                                                           minimum percentages of manganese (Mn) mixed with white lead. The results of the
                                                                                                                                           XRF analysis therefore show high quantities of iron (Fe) and lead (Pb) and traces of
                                                                                                                                           manganese (Mn). A small quantity of copper Cu was found which was probably used to
                                                                                                                                           make the pigments darker. In addition, it is evident how the pigment of the wall, darker
                                                                                                                                           than that of the floor, has a higher manganese (Mn) content than the brown used for
                                                                                                                                           the floor and the robe.




                                                                                                                                      94
  • Pictorial technique

   For investigation of the painting technique, infrared reflectography was used, which
enables the layer below that of the first pictorial layer to be observed and analyzed.
For the areas of sfumato (shaded), spectrophotometric colorimetry was used to try to
describe the pictorial technique employed by the artist to produce the chromatic effects
[19-20].
   The images in infrared reflectography, compared to those in the visible, obtained
at different wavelengths (NIR1 – NIR2 – NIR3), did not reveal the presence of the
preparatory drawing. From the images, however, the definition of a planned design is
clear, which places the main forms into the figurative space (as in the case of the paint-
ing “La Gioconda”). It is evident how the author’s need to define the individual figures
and groups of figures in monochrome emerges, thinking primarily in terms of contour
and tone, and then color.
   Figure 26 below, shows a detail of the painting relative to the hands, using infrared
reflectoscopy.




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE



       Figure 26. detail of the hands NIR4

   As regards colorimetry, various points were considered as follows:1,2,3,4,5, where
1 is the flesh tone in full light, 2,3,and 4, are the sfumato flesh tones and 5 is the
shaded flesh tone (Figure 27).
   The luminosity L of these points was evaluated, the value along the a+axis (red), the
value along the b+axis (yellow) and saturation C (Figure 28). The color of the sfumato,
which originates from white, is made using a mixture of red and green colored pig-
ments. The luminosity decreases proportionately from the lightest parts to the darkest
parts through the use of continuous and numerous veils of pigments which provide
poor coverage, a technique that produces a sfumato effect.



                                                                                             95
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                                    Figure 27. Points analyzed in spectrophotometric colorimetry



                                                                                                                                                                    L                ax             b
                                                                                                                                                      1                 54,3         7,96           22,11
                                                                                                                                                      2                 53,15        7,60           21,17
                                                                                                                                                      3                 50,44        7,63           17,58
                                                                                                                                                      4                 45,77        7,02           16,8
                                                                                                                                                      5                 30,80        3,16           7,06




                                                                                                                                           Figure 28. Colorimetric values of the flesh tones and colorimetric chart CIE-LAB


                                                                                                                                      96
   5. Conclusion

    Based on the results of the diagnostic and analytical investigations carried out: tex-
tile support, preparatory layer, primer, paint layer/film, siccative oil and radiocarbon
dating of the support, the following is a summary of the findings and considerations
with regard to the different historical periods:
    1) For the textile support, in the present case:
    a) Linen cloth, the weave of which is coarse and irregular.
    b) The size of the support is compatible with “standard” ones which were in common
use from the first half of the 1600s in the Flanders area [21-22].
    Moreover, in referring to historical sources relating to weaving over the centuries,
it is to be noted that weaving was done producing linen cloth that was tightly woven,
smooth and neat, using a light, fine yarn, throughout Europe from 1450. Towards the
mid-1500s, the use of diagonal and herring-bone patterned weaving became wide-
spread. In the 1600s the need for a rougher surface which was more suited to a faster
denser paint, determined the appearance of cheaper and less accurately worked can-
vases, characterized by a coarse grained textured and looser weaving [22-23].
    Consequently, if it is true that canvas was already used in 1450 [7, 17] throughout
Europe, it is just as certain that during Leonardo’s life – from 1452 to 1519 [19]– it was
not very widespread in Italy. This non-compatibility of historical periods is even more
evident when considering the type of weaving which, in this case, due to its coarse-
ness, leads us to consider a later period going from the mid-1500s on [19].
    However, to this can be added further historical sources which unanimously state
that Leonardo used wood as a painting support [24].
    2) The technique using oil, found in our painting was little used during Leonardo’s
lifetime, whereas the technique using tempera was more frequent.
    3) The use of calcium carbonate in the preparatory layer is rarely found in Italy up




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
to 1520-1530 and used very little even in subsequent periods, while it was commonly
used in Northern Europe from the second half of the 1400s [25-26].
    4) The use of the colored preparatory layer found in the work was first used from
the 1500s [25-26].
    5) According to a study carried out by Alain Duval on 155 coloured preparations
of seventeenth and eighteenth century French schools, baryte is not considered an
impurity associated with a compound, but it is hypothesized that it was instead added
to pigments voluntarily. Baryte is often found together with pigments based on iron
oxides. Thus it is believed that this product was introduced by a supplier of pigments.
As the drying oil and the barium sulfate have a similar index of refraction, this latter has
less covering capacity and is almost invisible. Consequently, Duval infers that a Paris
supplier developed a product designed specifically for the preparations. The addition
of barytes allowed merchants to reduce the expensive part of the pigment maintain-
ing the desired quantity and color for the realization of the preparations. According to
Duval’s study, in the period between 1620 and 1680 about 50% of the preparations
taken into consideration contain barytes, while after this period its use is less frequent
[17, 21].
    6) The colored primer on top of the bole preparation was used from the second half
of the 1500s [27].
    7) The presence of litharge in siccative oil spread across Northern Europe from the
end of the 1500s and later in Italy [28].


                                                                                               97
                                                                                                                                               8) Radiocarbon dating of the textile support dated the work to between 1490 and
                                                                                                                                           1670 with a probability of 93.1%: this dating includes the period of Leonardo’s life and
                                                                                                                                           work, while the reading for the dating between 1520 and 1660 with a probability of
                                                                                                                                           68.2%, excludes, instead, the period of Leonardo’s life and work.
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                               This information is illustrated in Figure 29, comparing the resulting time spans with
                                                                                                                                           the period of Leonardo’s life.
                                                                                                                                               It can therefore be demonstrated that this period does not essentially and signifi-
                                                                                                                                           cantly coincide with the previously mentioned time spans also because Leonardo, on
                                                                                                                                           the death of his patron Giuliano de’ Medici in 1516 left Italy for good. In fact, in May of
                                                                                                                                           1517 he was the guest of the French king, Frances I, in the castle of Clos-Luc, near Am-
                                                                                                                                           boise. He was given the title of premier peintre, architecte, et méchanicien du roi, and
                                                                                                                                           received a pension of 5,000 scudos: this, therefore excludes, his activity in Italy [19, 29].
                                                                                                                                               It is also a fact that he produced very little artwork in France, weakened as he was by
                                                                                                                                           old age and a possible cerebral thrombosis which paralyzed his right hand, whereas he
                                                                                                                                           was able to continue his studies and scientific research with passion and dedication [19].
                                                                                                                                               In addition to the above considerations regarding the technique used in executing
                                                                                                                                           the work under examination, the following annotations are given related to several
                                                                                                                                           aesthetic-stylistic aspects:
                                                                                                                                             • the face lacks the graphic elements of Leonardo’s painting and early works in
                                                                                                                                                 Leonardo’s style [30-31];
                                                                                                                                             • the painting is much too “soft” to belong to the period prior to 1500 [32];
                                                                                                                                             • even though hazy and misty, the drawing of the landscape in the background is
                                                                                                                                                 modest [33];
                                                                                                                                             • the brush strokes are not very full-bodied and lack the thickness of color, often
                                                                                                                                                 obtained by spreading the paint with the fingertips, which characterize Leonardo’s
                                                                                                                                                 landscapes.
                                                                                                                                               As regards the execution of the landscape in particular, the comparison between
                                                                                                                                           our painting and that of the Mona Lisa in the Louvre is highly significant [34].
                                                                                                                                               In the first the background is unclear and lacks depth, with a chiaroscuro that does not
                                                                                                                                           vibrate with luminous reflections and therefore devoid of the play of light and shadows,
                                                                                                                                           of that suffused brightness – dim light, enveloping atmosphere, almost dream-like from
                                                                                                                                           which the figures seem to emerge – typical of many masterpieces by Leonardo [29].
                                                                                                                                               In the second however, the fluidity of the colors with the changeability of the shad-
                                                                                                                                           ows and the soft and shady chiaroscuro disperses the line, producing with the crum-
                                                                                                                                           bling of the outlines, the atmosphere itself: that bluish darkness of the water and the
                                                                                                                                           sky, each relief vanishes, swallowed by the shadows [35].
                                                                                                                                               Similarly in the work under examination, the flesh tones are less rich than those
                                                                                                                                           subtle vibrations of light and color, that merging imperceptibly, give depth to the shad-
                                                                                                                                           ows and the sfumato endowing it with the maximum expressiveness and the evocative
                                                                                                                                           power of Leonardo’s painting [36].
                                                                                                                                               In conclusion, on the basis of what the research findings have objectively demon-
                                                                                                                                           strated from a historical-artistic, technical-material and diagnostic-analytical point of
                                                                                                                                           view, it is possible to say that the oil painting “Gioconda with columns” is a copy of the
                                                                                                                                           “Mona Lisa (Gioconda)” by Leonardo, attributable to a period between 1590 and 1660.
                                                                                                                                               Nevertheless, to complete the picture, the good workmanship, the readability and ex-
                                                                                                                                           pressiveness emanating from the work must be taken into consideration, the execution of
                                                                                                                                           which is of Nordic derivation, in particular German-Flemish and is influenced by the French
                                                                                                                                           school [20, 37-41], due to the presence of barytes as an additive in the preparation [17].


                                                                                                                                      98
     Figure 29. Temporal collocation of the work in relation to the period of Leonardo’s life (in red) and possible compatibility with the tem-
     poral findings related to the analyses performed (in green).




99
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                                                                                                                                                  Acknowledgements

                                                                                                                                                We would like to thank Lucio Calcagnile, CEDAD (Centro di Datazione e Diagnostica),
                                                                                                                                            Dipartimento di Ingegneria dell’Innovazione, Università del Salento; Gianluigi Colalucci,
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                            Conservazione e Restauro, Torrimpietra (Roma), and Irene Bonacini, M2ADL (Microchem-
                                                                                                                                            istry and Microscopy Art Diagnostic Laboratory), Università di Bologna, Ravenna campus.

                                                                                                                                                  References

                                                                                                                                            [1]     CONTI A., 1988, Storia del restauro e della conservazione delle opere d’arte,
                                                                                                                                                    Milano
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   Biographical notes

   Salvatore Lorusso is full professor in “Chemistry of the Environment and Cultural
Heritage” at the Scuola di Lettere e Beni Culturali of the University of Bologna, Italy. He
is Director of the Master in “Planning and promotion of artistic and cultural events”, of


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                                                                                                                                            the two book series’ “I beni culturali e l’ambiente”, and “La formazione e la ricerca nel
                                                                                                                                            settore dei beni culturali e ambientali” and the historical-technical Journal “Conserva-
                                                                                                                                            tion Science in Cultural Heritage”. He is the author of more than 370 publications in
                                                                                                                                            national and international journals and of 22 volumes covering various subjects and
S. Lorusso, C. Matteucci, A. Natali, S. A. Apicella, F. Fiorillo - Diagnostic - analytical study of the painting “Gioconda with columns”




                                                                                                                                            sectors, such as commodities, technology and environment, focusing in particular on
                                                                                                                                            the field of cultural and environmental heritage.

                                                                                                                                               Chiara Matteucci has a degree and is a specialized technician-diagnostician at the
                                                                                                                                            Department of Cultural Heritage of the Alma Mater Studiorum University of Bologna.
                                                                                                                                            She works extensively in the field of analytical-diagnostic investigations involving arti-
                                                                                                                                            facts from different areas of interest: artistic-historical, archaeological, archival-library
                                                                                                                                            and music. Her work is carried out in the Diagnostic Laboratory for Cultural Heritage in
                                                                                                                                            the Department of Cultural Heritage of Bologna University, Italy.

                                                                                                                                               Andrea Natali is professor at the Scuola di Lettere e Beni Culturali and a Research
                                                                                                                                            Fellow at the Department of Cultural Heritage of the Alma Mater Studiorum University
                                                                                                                                            of Bologna, Italy. His teaching and scientific work are carried out in the field of conser-
                                                                                                                                            vation and valorization of cultural and environmental heritage, authentication of works
                                                                                                                                            of art, art diagnostics and monitoring of the conservation environment.

                                                                                                                                               Salvatore Andrea Apicella has a degree in “Diagnostics and restoration”. He
                                                                                                                                            works in the Department of Cultural Heritage of the Alma Mater Studiorum University
                                                                                                                                            of Bologna, Italy.

                                                                                                                                              Flavia Fiorillo has a Master degree in “Science and technology for conservation
                                                                                                                                            and restoration”.




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