I materiali e la tecnica pittorica di Giulio Aristide sartorio nel ciclo “Il poema della vita umana” (1906-07): conoscenza e prevenzione per un progetto di musealizzazione
10.6092/issn.1973-9494/4192
Summary In 1906 Giulio Aristide Sartorio created the pictorial cycle “The Poem of Human Life" for the Central Hall of the Venice Biennale. To complete the cycle (over 240 m2) in just nine months, he used a special painting technique: “a mixture of wax, mineral turpentine and oils”.This cycle has had a complicated history of conservation. A project involving conservation and maintenance is needed to access Sartorio’s paintings. The first step in the conservation project involves the study of the entire cycle to identify the materials and the painting techniques adopted by the artist and to understand the degradation processes present on the paintings. This knowledge makes it possible to suggest some general guidelines for the correct presentation of the cycle for public viewing in a museum. A priority is the prevention of future degradation processes, usually due to exhibition conditions themselves, including excessive exhibition stress. This research shows that any museum display project must consider the specific technical and material characteristics of the artworks prior to their exhibition. RiassuntoNel 1906 Aristide Sartorio dipinse il ciclo "Il poema della Vita Umana" per il Salone Centrale della Biennale di Venezia. Per completare il ciclo (di oltre 240 m2) in solamente nove mesi, egli ricorse ad una particolare tecnica pittorica: “ una mistura di cera, essenza di trementina e oli”. Questa opera attraversò complicate vicende conservative ed era necessario un progetto di  conservazione e manutenzione per renderla visibile. Il primo passo per la stesura del progetto conservativo ha riguardato lo studio dell’intero ciclo per identificare i materiali e la tecnica pittorica adottata dall’artista e comprendere i processi di degrado in atto. Queste conoscenze danno la possibilità di suggerire delle linee guida generali per la corretta musealizzazione del ciclo, considerando prioritaria la prevenzione di futuri processi di degrado, generalmente legati alle condizioni di esposizione e stress correlati ad esse. Questa ricerca mostra che ogniprogetto di musealizzazione deve considerare le specifiche caratteristiche tecniche dell’opera prima di prevederne l’esposizione. RésuméEn 1906, Aristide Sartorio réalisa le cycle de peintures « Il poema della Vita Umana » (Le poème de la vie humaine) pour le Salon central de la Biennale de Venise. Pour compléter ce cycle de plus de 240 m2 en neuf mois seulement, il utilisa une technique picturale particulière, « un mélange de cire, essence de térébenthine et huiles ». Au niveau de la conservation, cette œuvre connut de nombreuses difficultés. Un projet de conservation et d’entretien était nécessaire pour la rendre visible. La première étape de la rédaction du projet de conservation fut l’étude de l’ensemble du cycle, pour identifier les matériaux et la technique picturale utilisée par l’artiste, et pour comprendre les processus de détérioration en cours. Les connaissances ainsi obtenues permettent de préconiser des lignes directrices générales pour la bonne muséalisation du cycle, la priorité étant la prévention des détériorations à venir, le plus souvent associées aux conditions d’exposition et aux sollicitations correspondantes. Cette recherche montre que tout projet de muséalisation doit considérer les caractéristiques techniques spécifiques de l’œuvre avant d’envisager son exposition. ZusammenfassungIm Jahr 1906 malte Aristide Sartorio den Zyklus "Il poema della Vita Umana" (etwa “Das Gedicht des menschlichen Lebens”) für den Zentralen Salon der Biennale von Venedig.  Um diesen Zyklus (über 240 m² groß) in nur neun Monaten fertigstellen zu kennen, griff er auf eine besondere Maltechnik zurück: “ein Gemisch von Wachs, Terpentin und Ölen”.  Dieses Werk unterlag komplizierten Konservierungsarbeiten und es war ein Projekt für die Konservierung und Instandhaltung notwendig, um es sichtbar zu machen. Der erste Schritt zur Erstellung dieses Konservierungsprojekts bestand im Studium des gesamten Zyklus, um die Materialien und die vom Künstler angewandte Maltechnik zu bestimmen und den eingetretenen Verrottungsprozess zu begreifen.  Die Kenntnis dieser Faktoren bieten die Möglichkeit, allgemeine Leitlinien für die korrekte Musealisierung des Zyklus zu liefern, wobei als prioritär die Verhinderung zukünftiger Verrottungsprozesse betrachtet wurde, die generell mit den Ausstellungsbedingungen und der damit einhergehenden Belastung verbunden sind. Diese Forschungsarbeit bezeugt, dass jedes Musealisierungsprojekt die spezifischen technischen Merkmale des Werks berücksichtigen muss, bevor es ausgestellt werden kann. ResumenEn 1906 Aristide Sartorio pintó el ciclo "Il poema della Vita Umana" (El poema de la Vida Humana) para el Salón Central de la Bienal de Venecia. Para completar el ciclo (de más de 240 m2) en tan solo nueve meses, el artista recurrió a una técnica pictórica particular: "una mezcla de cera, esencia de trementina y aceites". Esta obra atravesó complicadas vicisitudes por lo que se refiere a su conservación y un proyecto de conservación y mantenimiento era necesario para hacerla visible. El primer paso de la redacción del proyecto de conservación se ha centrado en el estudio del ciclo en su totalidad para identificar los materiales y la técnica pictórica adoptada por el artista y comprender los procesos de deterioro en marcha. Estos conocimientos brindan la posibilidad de sugerir algunos principios generales para musealizar el ciclo correctamente y se considera prioritaria la prevención de procesos de deterioro en el futuro, los cuales están generalmente relacionados con las condiciones de exposición y el estrés provocado por las mismas. Esta investigación muestra que todo proyecto de musealización debe tener en cuenta las características técnicas específicas de la obra antes de disponer su exposición. РезюмеВ 1906 году Аристид Сарторио создал цикл «Поэма человеческой жизни» для Центрального зала Венецианской Биеннале. Для завершения цикла (более 240 кв. м) всего лишь за девять месяцев он прибег к особой технике живописи: «смеси воска, скипидара и масла». Это произведение имело сложную историю с точки зрения его сохранения и нуждалось в проекте по сбережению и поддержанию, чтобы оставаться видимым. Первым шагом в создании проекта по сохранению явилось изучение всего цикла для определения материалов и техники живописи, принятых мастером, и выявить причины действующих процессов деградации. Эти знания позволяют дать общие указания для правильной музейной экспозиции цикла, отдавая приоритет предотвращению будущих процессов деградации, обычно связанных с условиями экспозиции и стресса, связанного с ними. Это исследование показывает, что любой проект музейной экспозиции при его подготовке должен учитывать специфические технические характеристики произведения. 摘要于1906年Aristide Sartorio  (阿里斯蒂德·萨尔托里奥)为威尼斯双年展的中心展厅画了"Il poema della Vita Umana(人生的诗歌)"一系列画。为了在9个月内完成此系列(240 多平方米大)，他使用了一种特别的画画技巧: “ 蜡、松节油精华和油类的混合物”。这幅作品经历了许多复杂的保留程序，当时为了展览它需要一种合适的保养与保存项目。保存项目的第一步是通过整个系列的研究来识别画家采用的材料和作画技巧以及了解已开始的退化过程。这些研究的结果对于此系列画正确地展示在博物馆里提供了指导方针以及在预防退化过程的基础上，分析了与它有关的展示的条件。这个研究证明了每个博物馆展示项目在展示作品之前都应当考虑到有关作品的技术特点。
application/pdf
1973-9494
4192
en
Henk van Keulen
Conservation Science in Cultural Heritage
zinc white
The materials and painting techniques of Giulio Aristide Sartorio in the pictorial cycle “The poem of human life” (1906-07): knowledge and prevention for a museum display project
Text.Serial.Journal
https://conservation-science.unibo.it/
13
Articles
2013-12-30
2014-02-09
2013-12-30
2015-11-02
379-393
CSCH
Henk van Keulen
2013/12/30
10.6092/issn.1973-9494/4192
379
1973-9494
zinc white
en
393
GHAN TYA, ODLYHA M., 1995, The effect of relative humidity and pigment type on paint films. Thermochim Acta; 269-270:755-767.
The materials and painting techniques of Giulio Aristide Sartorio in the pictorial cycle “The poem of human life” (1906-07): knowledge and prevention for a museum display project
https://conservation-science.unibo.it/article/download/4192/3643
13
T   HE MATERIALS AND PAINTING TECHNIQUES OF GIULIO ARISTIDE
    SARTORIO IN THE PICTORIAL CYCLE “THE POEM OF HUMAN
    LIFE”(1906-07): KNOWLEDGE AND PREVENTION FOR A MUSEUM
    DISPLAY PROJECT



    Francesca Caterina Izzo, Elisabetta Zendri·,●1 Eleonora Balliana, Laura Falchi
    Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari
    University of Venice

    Matteo Piccolo, Silvio Fuso
    Fondazione Musei Civici Venezia, Galleria Internazionale d’Arte Moderna di Ca’
    Pesaro, Venice

    Henk van Keulen
    Cultural Heritage Agency, the Netherlands



   Keywords: Giulio Aristide Sartorio, Ca’ Pesaro, Venice, encaustic painting
   technique, drying oils, beeswax, craquelure, lead white, zinc white

   1. Introduction and research aim

   In the spring of 1906 Giulio Aristide Sartorio (1860-1932) accepted to create a large
series of paintings on canvas to be placed in the Central Hall of the Venice Biennale of




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1907: “The Poem of Human Life”. The artist proposed a highly dramatic view of human
existence divided into four main scenes – called Light, Darkness, Love, Death – inter-
spersed with ten vertical panels (the Caryatids). The complex iconography presented
by Sartorio appears as a synthesis of the Mediterranean world and Northern culture.
Free of architectural elements and worked in monochrome, the painting cycle stands
out due to the exceptional arrangement of its figures in movement (Figure 1) [1].
   The works of Aristide Sartorio are of considerable interest, both for their undoubted
artistic value and for the particular technique used in the preparation of the painted lay-
ers. For this pictorial technique the artist used traditional procedures which he adapted
to the new demands of his time; it is the latter that are the starting point in the search
for suitable exhibition solutions for the entire cycle.
   To complete the 240 m2 of the cycle in just nine months, Sartorio used a special
painting technique, described by the author as “...a mixture of wax, mineral turpentine
and oils..called French encaustic…” [2,3] which enabled the painting to be completed
in a very short time. Sartorio was known to work with home-made mixtures of oil paints
(mixed with pigments and prepared himself in his studio) with the addition of several
waxes, natural resins, mineral spirits and gums. His brushstrokes appear fluid and the
resulting painted layers are characterised by a certain thickness (in some cases more
than 2 cm); he did not apply any final layers of varnish (Figure 2).


● Corresponding author: elizen@unive.it   

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                                                                                                                                    The artist’s declarations represent important documentation regarding the use of
                                                                                                                                 specific materials which, although showing relative stability with the passing of time,
                                                                                                                                 may be significantly affected by exposure conditions of the artworks.
                                                                                                                                    This cycle has experienced a complicated history of conservation since it was first
                                                                                                                                 moved. At the end of 1906, a few months after their completion, the canvases were
Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 sent by train from Rome to Venice; they were all installed just before the opening of
                                                                                                                                 the “Biennale D’Arte” exhibition (1907) and remained in situ until the following edition
                                                                                                                                 (1909). The works were later transferred to Ca’ Pesaro, home of the International Gal-
                                                                                                                                 lery of Modern Art in Venice. In 1938, the entire cycle was transported to the National
                                                                                                                                 Gallery of Modern Art in Rome, where it remained until the early 1950s, before return-
                                                                                                                                 ing to Ca ‘Pesaro. These frequent transfers (as well as subsequent ones), obviously
                                                                                                                                 implied the folding and rolling up of the canvases.




                                                                                                                                 Figure 1. Giulio Aristide Sartorio, “The Poem of Human Life” (1906-07) – Light, cm 503x646,
                                                                                                                                 International Gallery of Modern Art Ca’ Pesaro, Venice

                                                                                                                                    In the museum of Ca ‘Pesaro the paintings were only partially exhibited, up until the
                                                                                                                                 mid-1980s. They were probably displayed on different occasions and subsequently un-
                                                                                                                                 derwent some pictorial integration work, which included the mounting of new wooden
                                                                                                                                 frames. In 1995, the entire cycle was exhibited on the second floor of the museum,
                                                                                                                                 where it remained even after these rooms were transformed into an interim storage area
                                                                                                                                 for works of art (1996-2009). During this period, the cycle of paintings were barely ac-
                                                                                                                                 cessible and exposed to inappropriate environmental conservation conditions - a large
                                                                                                                                 amount of dust, due to the presence of wooden structures, the poor state of the windows
                                                                                                                                 and clutter in the storage space, due to other construction and maintenance materials.




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Figure 2. details of the painting technique from the “Darkness” panel, in which the fluidity of the
paint/brushstrokes and the thickness of the resulting painted layers are appreciable.

   When in 2011 the works were “liberated”, different degradation phenomena were
observed: small lacunae in the pictorial layers; the presence of large brown spots of
fungal origin; wide-spread craquelures; efflorescence; the flattening and the thinning of
the paint layers and damage to the wooden frames.
   A conservation and maintenance project was needed to protect and make Sartorio’s
paintings freely accessible.




                                                                                                            CONSERVATION SCIENCE IN CULTURAL HERITAGE
   Today this extraordinary cycle of paintings is located in the new storage area of the
Museum, where the environmental parameters (humidity, temperature, ozone level,
light) in the deposit have been set in accordance with optimal conservation conditions
as established by Italian legislation for the conservation of cultural heritage [4,5]; thus,
they are constantly monitored. The cycle is currently undergoing necessary mainte-
nance work and is anxiously awaiting to be returned to Ca’ Pesaro to be exhibited.
   The aims of the research are:
   - to study the materials and the painting technique used by Sartorio in the pictorial
cycle and to compare the obtained results with the artist’s declarations;
   - to identify the ideal conditions for its conservation and in addition suggest methods
for monitoring its conservation state which can easily be managed while the cycle is on
exhibition in the Museum.

   2. Experimental stage

   2.1. Preliminary observations of the cycle

   A preliminary evaluation of the morphology of the pictorial layers and the state of
conservation was performed by observing the different panels with visible light, oblique
light, and ultraviolet light with the aid of the contact digital microscope Dino Lite 413TL-
X (magnification 25-250 x) equipped with visible and ultraviolet light.

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                                                                                                                                   2.2. Sampling

                                                                                                                                    Micro-fragments from the painted layers and the canvases were taken from the
                                                                                                                                 artworks for further laboratory examination. Some overpainted areas were sampled
                                                                                                                                 as well. Table 1 reports the number and type of samples taken from the pictorial cycle.
                                                                                                                                    During this phase, only the four main scenes - Light, Darkness, Love, Death – were
Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 sampled, considering both the superior and the inferior panels which compose each
                                                                                                                                 single scene.

                                                                                                                                                   Table 1: typology of samples taken from the four panels
                                                                                                                                                         Typology and number of microsamples
                                                                                                                                                        Canvas/ground              painted             degraded/
                                                                                                                                       Panel
                                                                                                                                                            layer                   layers          overpainted areas
                                                                                                                                     Darkness                   2                      5                     2
                                                                                                                                        Light                   3                      6                     4
                                                                                                                                       Death                    2                      5                     4
                                                                                                                                        Love                    1                      7                     3

                                                                                                                                   2.3. Analytical techniques

                                                                                                                                    The pictorial fragments were analyzed to investigate the composition of the materi-
                                                                                                                                 als used by Sartorio, but also to identify the presence of any alteration products in the
                                                                                                                                 original layers and to detect any restoration materials used during the troubled con-
                                                                                                                                 servative history of the panels.
                                                                                                                                    The samples were firstly observed with an Olympus SZX16 optical microscope
                                                                                                                                 equipped for microphotography both in visible and UV light. Polished cross-sections of
                                                                                                                                 the samples considered to be the most significant were also prepared and then observed
                                                                                                                                 with a JEOL JSM 5600 LV scanning electronic microscope coupled with an OXFORD-
                                                                                                                                 Link Isis series 300 microanalysis system for elemental microanalysis(SEM-EDX).
                                                                                                                                    X-ray fluorescence (XRF) analyses were carried out using a Minipal Philips XRF
                                                                                                                                 instrument, equipped with a low power Rh-tube operating at 40 kV and 2.2 µA and a
                                                                                                                                 peltier cooled Si-PIN detector.
                                                                                                                                     Fourier-transform Infrared spectrometry was performed with a Thermo Nicolet
                                                                                                                                 Nexus 670 FTIR spectrophotometer combined with a Smart Orbit Single Reflec-
                                                                                                                                 tion Diamond ATR accessory, from 4000 to 400 cm -1 for 64 scans with 4 cm-1
                                                                                                                                 resolution.
                                                                                                                                    The Gas Chromatography-Mass Spectrometry (GC-MS) analyses were performed
                                                                                                                                 with a Thermo Quest GC-8000 instrument with a Supelco column Equity®-5, 30 m,
                                                                                                                                 0.25 mm, 0.5 µm interfaced with MS MD-800. The temperature program was set from
                                                                                                                                 120°C to 300°C with a ramp of 10°C/min, held for 3 minutes. The inlet temperature
                                                                                                                                 was 300°C, the MS interface was at 270°C. The MS was run in Full Scan mode (m/z
                                                                                                                                 40-600), 1.9 scans/sec. Solvent delay was set at 4.5 min. The transfer line was at
                                                                                                                                 240°C and the source temperature at 220°C. Electron Ionisation (EI) energy was 70eV.
                                                                                                                                 Samples were prepared using m-(trifluoromethylphenyl) trimethyl-ammonium hydrox-
                                                                                                                                 ide and left to react overnight [6,7].



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  3. Results and discussion

  3.1. Preliminary observations and determination of the state of conservation

    3.1.1. Painted layers
    The paint layers, as stated by the artist, were obtained by dispersing pigments in a
mixture of wax, turpentine and poppy oil [2]. Although it was assumed that this would
make the painting more elastic, this technique in fact produced a very dry stiff film of
paint. However, even if the paint surfaces present widespread and often extensive
craquelure, there do not seem to be any relevant detachments of the paint layer from
the canvas, leaving only the problem related to the stiffness of the paint film itself.
    The fractures on the pictorial surface are widespread, and are described by Sarto-
rio himself as “cracks in the colours” (figure 3 a and b). The “cracks” are particularly
evident in the areas painted with dark colours, but they are also present in the lighter
areas. These fractures might, in part, be due to the paintings being rolled up or on roll-
ers when they were transported from Rome to Venice in 1907, just after their execu-
tion. On the surface of the painting, the marks left from the materials (canvases and/or
paper sheets) used for rolling them up are, in fact, clearly visible.
    The thick brushstrokes, typical of the artist’s smooth and full-bodied technique
(sometimes more than 1 cm thick), appear flattened and crushed (figure 3 c and d) in
many areas. This is also probably related to the difficult history of conservation of the
large canvases and their unsuitable transport conditions while being transferred.
    On the canvases examined, the presence of numerous points of overpainting from
previous restoration interventions was also highlighted through the use of UV light.
Some of this over-painting was badly executed, since it covers both lacunae and parts
of the original painted areas.
    The presence of stains, mainly located in the lighter areas of the background and in




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
the paint layers of the various scenes, may be related to biological degradation.
    Finally, leakages or exudations of the paint film can be observed on the surface of
the artworks, and in some cases is quite extensive and highly visible especially in UV
light. At the moment, the origin of these coatings is not clear but it may be the result
of the migration of the paint binder on the surface or of the products used during past
restorations.

    3.1.2. Canvases
    As no evidence of relining is present on any of the examined paintings, it can be as-
sumed that the canvases are the original ones used by Sartorio. The canvases appear
to be all of the same typology, probably made of linen or tightly woven cotton of indus-
trial manufacture as suggested by the regularity of the warp and weft (Figure 4b) [8, 9].
    The canvases chosen by the artist are in fact characterised by a light grey primer,
probably obtained with rollers, evident from the uniformity of the ground layer. The cut
of the canvas along the edges, folded and nailed to the back, shows good consistency
and uniformity in its preparation, typical of manufactured products. Figure 4d shows a
detail of the outer edge of one of the canvases.
    On the back of the canvases there are extensive areas of an amber colour, probably
linked to the migration of the paint binder (Figure 4 a); several breaks – especially in
correspondence with lacunae in the painted layers- were noticed as well.



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Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 Figure 3. details of conservation state of the painted layers – A) craquelures and lacunae (50x),
                                                                                                                                 b) craquelure and detachement (200x), C) and D) flattened ares (30x)




                                                                                                                                 Figure 4. details of conservation state of the canvases: A) recto with visible lacunae (30x), B)
                                                                                                                                 warp and weft (200x) – details of the wooden stretchers: C) wooden joints and D) metallic joint




                                                                                                                           384
   3.1.3. Wooden stretchers
    Sartorio’s vast cycle of paintings has no picture frames and the canvases are
mounted on simple wooden stretchers linked by wooden joints (Figure 4 c). Several
conservation problems were found relating mainly to the tension of the woods compos-
ing the frame, which in many points is broken; to remedy, metal plates have been used
to join the broken wood together (Figure 4 d).
   3.2. Physical-chemical study of materials and painting technique

   All samples taken from the principal scenes were analysed as described in para-
graph 2.3. The results indicate that the same materials and painting technique were
employed by Sartorio in all four panels. Therefore, only the most emblematic examples
are reported hereafter to describe the cycle of paintings.
   The nature of the materials and the description of the painting technique are de-
scribed starting from the innermost layers (canvas), working toward the outer layers.
    3.2.1. Canvases and canvas preparation
    As described previously, Sartorio’s paintings were realised on industrially primed can-
vases presenting a light grey preparation. Figure 5 depicts the FT-IR-ATR spectra ob-
tained from the recto of a fragment of a canvas (Figure 5A) and from the verso with the
grey preparation (Figure 5B): the canvases appear to be composed of plant fibres, most
likely linen or cotton, while the ground layers are characterised by the presence of lead
white (basic lead carbonate) mixed with drying oil [10]. According to artists’ handbooks
of the period, industrially primed canvases were treated with several uniform layers of
lead white bonded with linseed oil, applied with rollers to achieve good uniformity [8,9].
    The presence of gypsum, oil and animal glue was detected in the white ground
layers (Figure 5C), thus suggesting the existence of additional preparatory layers, pre-
sumably applied by the artist himself, and superimposed on the lead white/oil layers.




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Figure 5. FT-IR-ATR spectra (4000-400 cm-1) of: A) canvas of plant origin, B) industrial priming
containing lead white and drying oil, C) grounding layers containing gypsum and animal glue.



                                                                                                   385
                                                                                                                                    3.2.2. Pictorial layers

                                                                                                                                    The thick brushstrokes, typical of the smooth and full-bodied technique of the
                                                                                                                                 artist, are clearly visible when observing the polished cross-sections of the paint
                                                                                                                                 samples. The images shown in Figure 6 give an idea of the complexity of Sartorio’s
                                                                                                                                 pictorial application of colours, the pictorial layers being composed of several su-
Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 perimposed layers of painting. The layers are marked by different thicknesses and
                                                                                                                                 contain several colouring pigments and aggregates, as evidenced in the SEM im-
                                                                                                                                 ages in Figure 7.




                                                                                                                                 Figure 6: cross sections of paint samples from “Light” (A-30x), “Darkness” (B-35 x), “Love” (C-30x)
                                                                                                                                 and “Death” (D-35 x) panels

                                                                                                                                    The optical images and SEM-EDX analysis give further evidence of the presence of
                                                                                                                                 numerous preparatory layers, previously analysed by FT-IR-ATR (Figure 7b).
                                                                                                                                    The analysis of the elements present in the paint layers obtained by EDX and XRF
                                                                                                                                 analysis, revealed the presence of lead, iron, calcium, sulphur, carbon, silicon, alu-
                                                                                                                                 minium, and zinc (see EDX spectra in Figure 7).
                                                                                                                                    The presence of these elements, combined with the FT-IR-ATR results, allow us
                                                                                                                                 to suppose that the artist’s palette included traditional and modern pigments, such as
                                                                                                                                 burnt Sienna (Figure 8b), yellow and red ochres, bone black, lead white (Figure 8a),
                                                                                                                                 zinc white and ultramarine blue (Figure 8c).
                                                                                                                                    The results relating to the organic component of the painting materials highlight
                                                                                                                                 even further the complex nature of Sartorio’s technique. The artist himself declared
                                                                                                                                 he employed “mixtures of wax, turpentine and oils” for his artworks, a statement
                                                                                                                                 which also finds confirmation in the analytical results. The medium used for exe-
                                                                                                                                 cuting the pictorial layers was in fact obtained by mixing drying oils with beeswax,
                                                                                                                                 whose typical IR absorption bands are present in the spectra reported in Figure 8
                                                                                                                                 [10, 11,12].


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Figure 7. SEM images and EDX spectra of A) paint bulk from a sample of the “Love” panel
(1000x) and B) paint stratigraphy of a sample from the “Death” panel (350x) in which lead, iron,
silicon, calcium, oxygen, potassium, aluminium and carbon were detected




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Figure 8. FT-IR-ATR spectra (4000-400 cm-1) of: A) lead white in drying oil, B) Burnt Sienna in
drying oil and C) ultramarine blue in linseed oil


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                                                                                                                                    These organic compounds were positively detected in all samples analysed by GC-
                                                                                                                                 MS, together with traces of an aromatic solvent (most likely mineral turpentine). Figure
                                                                                                                                 9 reports two examples of chromatograms of paint films after transesterification and
                                                                                                                                 GC-MS analysis. All the characteristic components of drying oils are easily identified
                                                                                                                                 here (such as methyl esters): dicarboxylic acids (such as azelaic, suberic and seba-
                                                                                                                                 cious acids), long chain saturated fatty acids (palmitic, stearic, lauric, myristic acids)
Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 and unsaturated oleic acid [13, 14]. The presence of beeswax is further confirmed
                                                                                                                                 by the detection of 15-hydroxy-octadecanoic acid from hydrocarbon chains with odd-
                                                                                                                                 numbered alkanes. Since Sartorio himself mixed his oils and wax with mineral spirit
                                                                                                                                 to obtain a paint that was ready to use and fluid, the proportions of the different com-
                                                                                                                                 pounds are not consistent, especially considering the differences in the thickness of
                                                                                                                                 the paint layers.
                                                                                                                                    Furthermore, GC-MS results allowed to discriminate the use of different lipidic
                                                                                                                                 binders based on the ratios between palmitic and stearic acids (P/S) [13,14]. Sar-
                                                                                                                                 torio seems to prefer to use a mixture of poppy oil (P/S values around 3.3-4, see
                                                                                                                                 Figure 9 a) and beeswax for the execution of light brushstrokes: this choice can
                                                                                                                                 be explained considering that poppy oil tends to yellow less with time compared to
                                                                                                                                 linseed oil, thus avoiding the unpleasant yellowing of light colours (such as white,
                                                                                                                                 light blue, green ) [8,9]. Linseed oil (P/S values around 1.3-1.7) was detected in
                                                                                                                                 correspondence of the dark colours; it was moreover found, that for executing the
                                                                                                                                 drawings the artist diluted carbon black and burnt Sienna with boiled linseed oil,
                                                                                                                                 as suggested by the ratios between azelaic and suberic acids (A/Sub), which are
                                                                                                                                 around 2 [12,13,14]. These findings once more confirmed the declaration of the
                                                                                                                                 painter about his painting technique.




                                                                                                                                 Figure 9: Total ion current chromatogram of A) a white paint sample and B) a dark-brown paint
                                                                                                                                 sample from “Light” panel and after transesterification and GC-MS analysis (internal standard =
                                                                                                                                 nonadecanoic acid)




                                                                                                                           388
   3.2.3. Products resulting from degradation of the paintings, from previous
   restoration interventions and from transport

    The large canvases by Sartorio present different degradation products resulting from
the natural ageing of the materials used by the artist. In particular, oxidation and cross
linking products of the layer composed of drying oils were identified, together with the
formation of metallic soaps. These carboxylates can be formed after hydrolysis of the
fatty acid moieties of the triglycerides of drying oil with metal-based pigments [10,15]: in
Sartorio’s cycle, lead and zinc soaps were detected in the whitish efflorescence visible
on the paintings’ surfaces. Lead carboxylates probably migrated from the lead/oil-based
preparation and from the painted layers to the surface layers. The presence of zinc
white, furthermore, might explain the presence of unsaturated fatty acids (in particular
oleic acid), as observed elsewhere [16, 17, 18]. It seems that zinc oxide in proximity of
a lipidic medium forms a packed structure which is able to trap unsaturated fatty acids
in the painted layer. This effect can also occur years after the oxidation process is com-
plete, probably because of the stability in the zinc oxide-oleic acid structures.
    In addition, the materials and products used for transporting the canvases appear
to be in many points inconsistent and show evidence of degradation processes in act.
Some areas of the paintings have an extremely fragile and rigid surface, due to the
presence of a glue (most likely rabbit skin glue, visible in the spectrum reported in
Figure 8b). The glue was presumably applied on the surface of the paintings to glue
textiles/paper and then to roll up the canvases for transfer.
    The presence of paraffin wax and watercolours, detected by FT-IR and GC-MS in
several damaged areas, is due to previous consolidation and retouching work.


   4. Future perspectives: Preventive conservation and monitoring project for




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE
   Sartorio’s cycle

     The chemical analysis of the paint samples revealed the use of lipidic materials
mixed with beeswax. Based on the results obtained, the ageing processes involving
lipidic compounds are virtually completed, assuring a condition of relative stability of
the paint film [11,12,19]. Future transformation processes will therefore be eventually
linked to specific environmental conditions regarding conservation, such as: daily or
seasonal thermo hygrometric variations, irradiation of the paint film by natural and ar-
tificial light, as well as by the presence of gaseous pollutants (NO2, O3, VOC) [20-25].
     Based on the present state of conservation of the paintings, a project of preventive
conservation is here proposed, aimed at:
     - monitoring environmental conditions for the correct conservation of the pictorial
cycle (“passive” conservation);
     - reducing direct interventions on the paintings (“active” conservation) and promot-
ing minimal and focused interventions;
     - reducing the economic impact of restoration treatments.

   4.1. Preventive conservation: Environmental monitoring

   Considering the huge dimensions of Sartorio’s cycle (240 m2 in total) and the pos-
sibility the canvases will be exhibited in a museum or in a historic building (where


                                                                                               389
                                                                                                                                 control of the microclimate is often quite complex) in the future, the following are some
                                                                                                                                 proposals for guidelines regarding what are considered to be the most important mi-
                                                                                                                                 croclimatic parameters for a good conservation environment.
                                                                                                                                     Based on well-known parameters [4,5, 20-25], values below 60% of relative humid-
                                                                                                                                 ity (HR%) and 25°C of temperature (T) respectively, are indicated for the conservation
                                                                                                                                 of paintings on canvas as ideal exhibition conditions. These values are generally rec-
Izzo, Zendri, Balliana, Falchi, Piccolo, Fuso, van Keulen - The materials and painting techniques of Giulio Aristide Sartorio




                                                                                                                                 ommended for all paintings on canvas, considering not only the necessity of controlling
                                                                                                                                 possible degradation processes of the pictorial film, but also the physical-mechanical
                                                                                                                                 behaviour of the artworks in their entirety (interaction of canvas and wooden frame),
                                                                                                                                 otherwise subjected to dimensional changes that may affect their stability [26,27].
                                                                                                                                     The monitoring of RH% and T must also involve the back of the canvases, avoiding
                                                                                                                                 their direct contact with the walls and thus reducing the occurrence of condensation.
                                                                                                                                     The monitoring of humidity and temperature can be performed with the help of spe-
                                                                                                                                 cial probes installed directly in the room of the Museum, which are able to measure
                                                                                                                                 the two parameters continuously. This will make it possible to monitor environmental
                                                                                                                                 conditions over long periods of time and also to assess the incidence of anthropogenic
                                                                                                                                 impact as a result of special exhibitions or in relation to opening times and influx of
                                                                                                                                 visitors to the Museum.
                                                                                                                                     The monitoring will also include the control of gaseous species responsible for the
                                                                                                                                 degradation of the paint film, with particular attention given to O3, NO2 and VOC which
                                                                                                                                 may, for example, trigger chemical changes in the lipidic matrix [20-25].

                                                                                                                                   4.2. Monitoring of the state of conservation of the paintings

                                                                                                                                     Control of the state of conservation will be carried out through non-invasive tech-
                                                                                                                                 niques with periodic measurements on painted areas taken as references for enabling
                                                                                                                                 the identification of possible degradation processes.
                                                                                                                                     Taking into account that degradation processes of pictorial films generally involve
                                                                                                                                 morphological variations in the film surface, observation with a contact microscope of
                                                                                                                                 selected points (considering thickness and typology of the painted layers), associated
                                                                                                                                 with colorimetric measurements (CIELab method, evaluation of tristimulus parameters
                                                                                                                                 L*, a*, b*) will be useful to identify degradation processes due to both endogenous
                                                                                                                                 (degradation of paint materials) and exogenous (dust deposition, lighting) factors.
                                                                                                                                     Whenever any relevant morphological and/or chromatic variations occur, microsa-
                                                                                                                                 mples will be taken and analysed to determine the entity and the origin of the actual
                                                                                                                                 degradation processes and to consequently modify the environmental factors and con-
                                                                                                                                 ditions responsible for these transformations.
                                                                                                                                     In addition, to monitor alterations in the wooden parts, in relation to the thermo-
                                                                                                                                 hygrometric conditions of the exhibition environment and intervention in the event of
                                                                                                                                 significant changes, dynamometers will be installed in points previously affected by
                                                                                                                                 breakdown of the wooden frames for controlling the tension of the canvases.

                                                                                                                                     Knowledge of the materials and techniques used by Sartorio gives the possibility of
                                                                                                                                 suggesting some general guidelines for correct “musealization”, considering as a prior-
                                                                                                                                 ity, the prevention of future degradation processes, which are usually due to exhibition
                                                                                                                                 conditions themselves and excessive exhibition-related stress.
                                                                                                                                     This research shows how any museum project must consider the specific technical
                                                                                                                                 and material characteristics of artworks prior to their exhibition.


                                                                                                                           390
References

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                                                                                                                                    Biographical notes

                                                                                                                                    Francesca Caterina Izzo graduated in “Chemical Sciences and Technologies for
                                                                                                                                 the Conservation of Cultural Heritage” at Ca’ Foscari University of Venice in 2007.
                                                                                                                                 During her European PhD in Chemical Sciences, she collaborated with RCE (The
                                                                                                                                 Netherlands Cultural Heritage Agency) into the Modern Oil Project and focusing on
                                                                                                                                 the organic analyses of oils and additives used in manufactured oil paints. Since 2012
                                                                                                                                 she has been working as a researcher in Conservation Science for Contemporary Art
                                                                                                                                 in Venice, collaborating with several Italian and international organizations and institu-
                                                                                                                                 tions. She collaborates also with restorers, conservators, public and private collec-
                                                                                                                                 tions. She has been involved in several European projects dealing with the Science,
                                                                                                                                 Education and Conservation of Cultural Heritage.

                                                                                                                                    Elisabetta Zendri graduated in Industrial Chemistry in 1988 at the Ca’ Foscari Uni-
                                                                                                                                 versity of Venice. Since 2001 she has been associate professor in the same University.
                                                                                                                                 She has been in charge of several projects: MIUR-COFIN, MIUR-FIRB and two MIUR-
                                                                                                                                 PRIN projects on materials and technologies for the conservation of modern painting.
                                                                                                                                 She is the scientific coordinator for Ca’ Foscari, the MACC Modern Art Conservation
                                                                                                                                 Centre. Her research activities are developed in collaboration with national and inter-
                                                                                                                                 national Universities. She has published more than 140 publications in national and
                                                                                                                                 international journals.

                                                                                                                                   Henk van Keulen is a conservation scientist employed by the Cultural Heritage
                                                                                                                                 Agency of the Netherlands (RCE) since 1994. He has trained in analytical chemistry
                                                                                                                                 and specifically in Gas Chromatography Mass Spectrometry. He is currently engaged


                                                                                                                           392
in the analyses of traditional and modern organic materials from different source, such
as paintings, furniture and modern art. His experience and knowledge is applied in
projects such as POPART (Preservation of Plastic Artefacts in Museum Collections),
20th Century Oils, RadICal (Recent Advances in Characterizing Asian Lacquer, Getty
Center, Los Angeles) and Dry Cleaning of Unvarnished Water sensitive Oils.

   Eleonora Balliana obtained a Degree in Conservation of stone materials from the
International University of Art of Venice in 1997. She graduated in Chemical Sciences
and Technologies for Conservation and Restoration at Ca’ Foscari University of Venice
in 2007. Since 2009 she has been a researcher in Conservation Science at Ca Foscari
University (Faculty of Science). Since then she has been working in the Laboratory of
Conservation Sciences for Cultural Heritage Her topics of interest include: the study of
the art materials and interaction with the environment, the characterization and study
of degradation processes of plaster, natural stone, the development and characteriza-
tion of new low-impact and sustainable solutions for the cultural heritage sector.

   Laura Falchi graduated in “Chemical Sciences and Technologies for the Conserva-
tion of Cultural Heritage” at Ca’ Foscari University of Venice. She has increased her
professional knowledge by working as a trainee with two companies in the building
industry. In September 2010 she started her Ph.D studies Chemical Science at Uni-
versity Ca’ Foscari and in 2013 defended her PhD thesis on the study of new water-
repellent systems for artificial stone materials.

   Silvio Fuso graduated in Philosophy at the University of Padua, Italy. At the end of
the 70s he directed, with the painter Mario Deluigi, the International University of Art
(UIA) in Venice. Since the early 80s he worked as an exhibition curator at the Fortuny
Museum in Venice, where he also conceived and was in charge of the video graphic




                                                                                                       CONSERVATION SCIENCE IN CULTURAL HERITAGE
sector. From 1994 to 2006, he was Director of the Fortuny Museum, where he organ-
ized exhibitions, workshops and events devoted in particular to photography, video
and design. In 2007 he became Director of the International Gallery of Modern Art in
Venice.

    Matteo Piccolo graduated in Conservation of Cultural Heritage at the University of
Udine and has a diploma in Archival Science, Palaeography and Diplomatics from the
School of State Archives of Venice. He is the author of several publications and essays
in the field of art history, relating in particular to the XIX and XX century. He is a curator
of the International Gallery of Modern Art in Venice, where he contributed to the editing
of the general catalogue of sculptures and has organized many exhibitions. For some
years he has been vice-president of the “Centro Studi Storici di Mestre”.




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