10.48255/1973-9494.JCSCH.21.2021.10
La ricerca prende in esame un sarcofago bizantino in piombo, rinvenuto a Jerash (Gerasa), in Giordania, conservato nel magazzino del Museo di Jerash con il n. 1824. Il sarcofago è stato esposto a condizioni di conservazione non idonee che hanno causato gravi danni. L’esame allo stereomicroscopio ottico e al microscopio elettronico a scansione ha rivelato che il sarcofago soffriva di vari fenomeni di deterioramento, ad esempio erano presenti strati di corrosione, pieghe e crepe varie. L’analisi del sarcofago da parte dell’unità EDX collegata a un microscopio elettronico a scansione e fluorescenza a raggi X, ha mostrato che conteneva il 98% di piombo, oltre a una piccolissima percentuale di altri elementi come ferro, alluminio, sodio, silicio e carbonio. L’analisi mediante diffrazione di raggi X ha rivelato che il sarcofago conteneva anche minerali, che includevano grafite (C), piombo (Pb), litargio (PbO), cerussite PbCO3, idrocerussite 2PbCO3.Pb (OH)2. Sono state quindi eseguite le fasi di restauro e manutenzione del sarcofago in piombo, seguite da pulitura meccanica e chimica e raddrizzatura delle zone deformate. Sono state integrate anche le parti mancanti e i quattro lati del sarcofago sono stati assemblati utilizzando il plexiglass come materiale di supporto. Sono stati effettuati trattamenti con una soluzione di benzotriazolo in etanolo alla concentrazione del 5%, e con Paraloid B72, anch’esso alla concentrazione del 5% (coating). Anche la copertura del sarcofago è stata completamente restaurata. Al termine degli interventi di restauro e conservazione del sarcofago, è stata progettata una teca in vetro trasparente dello spessore di 1 cm per la sua esposizione, all’interno del Museo di Jerash, in un ambiente con umidità relativa del 25-30% e temperatura di 20-22 °C.
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Bilal Fawwaz al-Boorini
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Conservation Science in Cultural Heritage
conservation
Deterioration and conservation of an archaeological Byzantine lead sarcophagus from Jerash, Jordan
Text.Serial.Journal
https://conservation-science.unibo.it/
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2022-08-02
2022-07-19
2022-08-02
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Bilal Fawwaz al-Boorini
2021
10.48255/1973-9494.JCSCH.21.2021.10
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Yarmouk University and Ministry of Tourism and Antiquities, Jordan
1973-9494
conservation
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Deterioration and conservation of an archaeological Byzantine lead sarcophagus from Jerash, Jordan
https://conservation-science.unibo.it/article/download/15252/14478
21
D    ETERIORATION AND CONSERVATION OF AN
     ARCHAEOLOGICAL BYZANTINE LEAD SARCOPHAGUS
     FROM JERASH, JORDAN

   Wassef Al Sekhaneh *    1




   Department of Conservation and Management of Cultural Resources
   Faculty of Archaeology and Anthropology, Yarmouk University, Jordan

   Gehan Adel Mahmoud
   Restoration Department
   Faculty of Archaeology, Luxor University, Egypt

   Abdelrahman Elserogy
   Restoration Department
   Faculty of Archaeology, Fayoum University, Egypt

   Bilal Fawwaz al-Boorini
   Yarmouk University and Ministry of Tourism and Antiquities, Jordan

   Keywords: Jordan, Gerasa, Jerash museum, lead sarcophagus, conservation

   DOI: 10.48255/1973-9494.JCSCH.21.2021.10



   1. Introduction

    Lead sarcophagi were used for burial in ancient Jordan [1]. An example of a lead
sarcophagus is housed in the Archeological Technicalities Store at the Directorate of
Jerash Antiquities Governorate with the museum artifact number (1824). The sarcoph-
agus was found in the southeastern corner of the area (cemetery) in Jerash, in Jordan
(Figure 1); its height is about 150 cm from the level of the ground with a depth of ap-
proximately 55 cm; it retains all the essential elements, including parts of the side
stones which supported the sarcophagus and the lead cover. Both the sarcophagus
and its cover are ornamented with raised, relief-type drawings of human forms, stat-
ues, and twisted ropes on all sides of the body and the cover. The manufacture of the
sarcophagi was usually identical and took place in the nearby area in some local work-
shops [2]. The lead was poured into the base and the long sides of the sarcophagus
together, while the short elements were poured separately.
    The lids of the lead sarcophagi discovered in Jordan are either plain or slightly
curved [3-4]. Craftsmen carefully welded the edges and corners, that were carefully
handled, to seal the lid and the sarcophagus together. This method of welding for the
final closure of the ark was done for funerary reasons only. The molds that were used
to shape these sarcophagi were often made of leather-hard pottery, or finely polished
pottery so that the decorations could be clearly distinguished [5]. The molds used to



   * Corresponding author: Sekhaneh@yu.edu.jo
                                                                                                                                  produce some of the decorative ornaments were divided within a frame or an architec-
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine



                                                                                                                                  tural unit; in other cases, it was possible to add the decoration alone. This meant the
                                                                                                                                  molds could be used multiple times and moreover, as they were made of wood, they
                                                                                                                                  were biodegradable [2].
                                                                                                                                      The reason for the decoration of the sarcophagi can be found in the choice of
                                                                                                                                  decorative elements whose meaning or potential symbolism reflects the religious
                                                                                                                                  consequences for the dead. Modest lead sarcophagi bear common decorative ele-
                                                                                                                                  ments, such as symbols of divinity, showing, for example, a partial [6] or a complete
                                                                                                                                  scene of the goddess Rhenionius the goddess of wine used to protect the deceased
                                                                                                                                  from human beings and to benefit from their entry into the realm of death [7]. Even
                                                                                                                                  simple decorations such as the regular lines placed throughout the various sarcoph-
                                                                                                                                  agi in Jordan were also used to protect the deceased from evil, bearing in mind that
                                                                                                                                  the Roman Period was one of idolatry [8]. Lead sarcophagi are considered of very
                                                                                                                                  great importance to the history of any archeological site [9]. Based on the funeral
                                                                                                                                  drawings, statues, and the twisted ropes that spread across the body and cover of
                                                                                                                                  the sarcophagus examined in the present study, the sarcophagus is referred to the
                                                                                                                                  Byzantine period. The leaden coffer was exposed to many factors of mechanical
                                                                                                                                  damage, as a result of its transferal from the place where it was excavated to its
                                                                                                                                  present storage place.
                                                                                                                                      After an initial inspection of the sarcophagus and due to the damage caused by
                                                                                                                                  poor transport, storage, and unsuitable conservation conditions, it was found that the
                                                                                                                                  sarcophagus was in urgent need of maintenance and restoration [10] (Figure 1). The
                                                                                                                                  measurements of the sarcophagus were also recorded as follows: cover − 216 cm
                                                                                                                                  length, 95 cm width, 15 cm depth; body – 210 cm length, 61 cm width at the head, and
                                                                                                                                  60 cm width at the feet. Height of the sides: max. height 45 cm, to min. height 44 cm at
                                                                                                                                  the head and feet. The aim of this study, therefore, was to examine the deterioration
                                                                                                                                  phenomena and subsequently proceed with the treatment, restoration, and preserva-
                                                                                                                                  tion of the lead sarcophagus displayed at the Archeological Technicalities Store at the
                                                                                                                                  Directorate of Jerash Antiquities Governorate in Jordan.




                                                                                                                                  Figure 1. Sarcophagus in the store of the Directorate of the archaeology, province of Jerash. A)
                                                                                                                                  The sarcophagus during its discovery in 2003; B) damaged part of the sarcophagus; C) detail of
                                                                                                                                  side; D) decorated side; E) detail of decoration on outside; F) decoration on outside: details of
                                                                                                                                  cracks, disfigurement of the body and corners of the sarcophagus; repeated decorative unit on
                                                                                                                                  the sarcophagus representing an ancient Greek legend.


                                                                                           222
    1.1. Decorations on the sarcophagus

  The scene depicts Hermes Psychopompos bringing the soul of a man before Hades
and Persephone. Hermes is wearing a short mantle fastened on his left shoulder and is
holding a caduceus in his left hand; he is accomplishing his duty as Hermes Psychopom-
pos, or conductor of souls in the underworld. The god is turning around and looking at
the veiled man representing the deceased owner of the sarcophagus, whom he is lead-
ing by the hand [11]. The man is holding an object or perhaps a wrapped paper with his
right hand. On the right, Persephone is holding a special type of torch in her right hand,
which was used in the Eleusinian mysteries, and a long torch in her left hand. Behind her
is Hades, who is looking at her and holding a cornucopia with both hands or left hand.
The abduction is often depicted in Greek art with Persephone being taken away on Ha-
des’ chariot, sometimes accompanied by the messenger god, Hermes [12].


    2. Materials and Methods

    Optical microscopy (OM) and stereomicroscopy (SM) were used to provide a wide
range of data relating to the patina features and surface characteristics of the lead sar-
cophagus. Scanning electron microscopy equipped with energy-dispersive X-ray micro-
analysis (SEM-EDX) was used for investigation and elemental analysis of the deteriora-
tion phenomena. SEM micrographs and EDX spectra of the selected samples were
obtained by using a JSM-6380 LA instrument, equipped with a Link EDX operating up to
30 kV. An X-ray diffractometer (XRD) was used to identify the corrosion compounds to
obtain complete information about the corrosive medium, using a Philips X-ray Diffrac-
tometer type: PW1840, tube anode: Cu, start angle (2 θ º): 1 º and end angle (2 θº): 60º.


    3. Results




                                                                                                        CONSERVATION SCIENCE IN CULTURAL HERITAGE
    3.1. Optical microscope examination

    The optical microscope examination of the corrosion layer showed the surface of
lead metal and the lead corrosion compounds: the irregularity of the surface is due to
the storage of the sarcophagus in inappropriate conditions. Many fissures and cracks
were also observed, in addition to soil deposits on the surface (Figure 2).




Figure 2. Optical microscope image of the lead sample. A) red corrosion on surface; B) irregularity
of surface and presence of soil deposits.


                                                                                                      223
                                                                                                                                      3.2. Stereo microscope examination
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine




                                                                                                                                    The optical microscope examination of the lead samples showed the presence of
                                                                                                                                  grains of soil in which the sarcophagus was buried, sticking to the surface; the pres-
                                                                                                                                  ence of deep cracks in different directions; the corrosion products have heteroge-
                                                                                                                                  neously interfered with the lead metal. There are also gaps, cavities, and areas of ero-
                                                                                                                                  sion in different parts of the lead surface (Figure 3A, B, C, D).




                                                                                                                                  Figure 3. A) Erosion, cracks, and heterogeneous corrosion layers; B) soil grains mixed with corro-
                                                                                                                                  sion products; C) corrosion layers on the surface of the lead sample; D) deep cracks and corrosion
                                                                                                                                  compounds.


                                                                                                                                    3.3. Scanning Electron Microscopy (SEM) examination

                                                                                                                                    Scanning electron microscope investigations illustrated that the unevenness and
                                                                                                                                  roughness of the surface is the result of erosion due to its being buried in the soil with
                                                                                                                                  components that have caused the formation of corrosion products. The presence of var-
                                                                                                                                  ious separations and cracks were also observed. The corrosion compounds appeared
                                                                                                                                  as a dark color on the surface, interfering with the lead metal (Figure 4A, B, C, D).




                                                                                                                                  Figure 4. Scanning electron micrograph: A) corrosion layer; B) cracks and disintegration with voids,
                                                                                                                                  C) erosion and presence of corrosion products; D) corrosion compounds appear in a dark color on
                                                                                                                                  the surface.


                                                                                       224
   3.4. Elemental analysis by EDX Unit

    Scanning electron microscopy (SEM) equipped with energy-dispersive spectrome-
try (EDX) was used to study the lead samples of the sarcophagus. The EDX analysis
of the corrosion layer representing the metallic core revealed that it contains Pb as the
major element, and small amounts of Si, Ca, O, Al, Mg, K, Na, and Fe, (Figure 5A and
B and Tables 1A and B).




                         Figure 5. A) EDX pattern of the lead sample.


Table 1A. EDX analysis results of the lead sample.




                                                                                              CONSERVATION SCIENCE IN CULTURAL HERITAGE




                         Figure 5. B) EDX pattern of the lead sample.


Table 1B. EDX analysis results of the lead sample.




                                                                                            225
                                                                                                                                      3.5. XRF elemental analysis
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine




                                                                                                                                     The XRF analysis of the lead samples revealed that it contains Pb as the major
                                                                                                                                  element, in addition to Ca, Fe, and Ir as an impurity, (Figure 6A and B and Table 2).




                                                                                                                                          Figure 6. A) XRF pattern of the lead sample; B) XRF pattern of the lead sample.

                                                                                                                                  Table 2. XRF Analysis results of the lead sample.

                                                                                                                                     Element             Percentage %                 Oxide                 Percentage %
                                                                                                                                     Ca                  0.56380                      CaO                   15.64786
                                                                                                                                     Fe                  0.24212                      Fe2O3                 0.81464
                                                                                                                                     Ir                  1.09809                      IrO2                  0.14801
                                                                                                                                     Pb                  97.17810                     PbO                   83.38949


                                                                                                                                      3.6. X-Ray diffraction analysis

                                                                                                                                     The XRD spectrum of the samples consists of graphite (C), lead (Pb), litharge (PbO),
                                                                                                                                  cerussite (PbCO3), hydrocerussite (2PbCO3.Pb (OH)2) (Figure 7A and B and Table 3).




                                                                                                                                                           Figure 7. A) XRD pattern of the lead sample.


                                                                                        226
                         Figure 7. B) XRD pattern of the lead sample.

Table 3. XRF analysis results of the lead sample.


   No.                Mineral Name                        Chemical Formula


   1                  Graphite                            C

   2                  Lead                                Pb

   3                  Litharge                            PbO




                                                                                           CONSERVATION SCIENCE IN CULTURAL HERITAGE
   4                  Cerussite                           PbCO3

   5                  Hydrocerussite                      2PbCO3.Pb (OH)2



    4. Conservation and protection against corrosion

    4.1. Adjustment and rectification of the torsion

    This process is one of the most challenging treatments, as it took a long time
and great effort. During the process, great care was taken of the existing decora-
tions, so as not to deform their appearance, as a possible result of the operation of
gentle knocking using silicon hammers. All sides of the sarcophagus (cover and
body) underwent the rectification process and adjustment of the torsion, using sili-
con hammers, so as not to leave traces on the inherently soft lead material. Iron vis-
es were also used with traction on each side of the sarcophagus between two
boards of wood; pressure was applied gradually over fifteen days, so as not to
cause any sudden stress which could lead to the material (lead) breaking or crack-
ing (Figure 8 A, B and C).


                                                                                         227
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine




                                                                                                                                  Figure 8. A) The sarcophagus after being moved from the warehouse to the laboratory; B) cover
                                                                                                                                  of the sarcophagus during the process of rectification; C) gentle knocking using a hammer with a
                                                                                                                                  silicon head, the cross is clearly visible on the cover.


                                                                                                                                     4.2. Cleaning

                                                                                                                                      This stage was aimed at removing the dirt and damaged products that distorted the
                                                                                                                                  shape of the sarcophagus and included dust, foreign particles, and rust products, etc.
                                                                                                                                  During this process, the dirt was removed by breaking the bond between it and the ar-
                                                                                                                                  cheological soiled surface, mechanically and chemically. The cleaning leads to remov-
                                                                                                                                  ing all the soil marks, restoring the ‘readability’ of the decoration of the sarcophagus
                                                                                                                                  and its subtle details. The cleaning also involved the removal of deformed external and
                                                                                                                                  distorted parts of the sarcophagus surface. The cleaning stage is an initial stage of
                                                                                                                                  treatment followed by other multiple steps and must therefore be carried out accurate-
                                                                                                                                  ly and with acute awareness, to conserve and repair the damaged signs and features
                                                                                                                                  of the sarcophagus.


                                                                                                                                    4.2.1. Mechanical cleaning

                                                                                                                                    Mechanical cleaning is the most controllable method and the safest, if done accu-
                                                                                                                                  rately. It is also easy and safe to use, as it does not produce any chemical products that
                                                                                                                                  may cause damage to the archeological object. Mechanical cleaning usually gives
                                                                                                                                  highly excellent cleaning results; hence, chemical cleaning may not be required [13]. It
                                                                                                                                  is, therefore, preferable to use mechanical cleaning and to resort to chemical cleaning
                                                                                                                                  only if strictly necessary. The purpose of mechanical cleaning is to maintain the signs
                                                                                                                                  of deterioration without causing any damage or surface scratching of the lead or mak-
                                                                                                                                  ing any change in the shape and color of the sarcophagus. Mechanical cleaning, more-
                                                                                                                                  over, does not require the addition or removal of any material that weakens or damag-
                                                                                                                                  es the lead. Mechanical cleaning includes the removal of surface dust and suspended
                                                                                                                                  dirt on the surfaces of calcined sediments, especially from the soil accumulated during
                                                                                                                                  the burial process and the products of corrosion [14].
                                                                                                                                       This is done by using various types of brushes, sponges, an air compressor, and a
                                                                                                                                  vacuum cleaner with different brush shapes, etc. as well as other various fine tools,
                                                                                                                                  such as needles, dispensers, dental tools, spatulas, different sized scalpels; the most
                                                                                                                                  appropriate tool is selected and used, according to the quality and strength of the lead
                                                                                                                                  to be treated, and on condition that removal of the dirt must be done without directly
                                                                                                                                  penetrating the surface of the archeological object. In fact, cleaning of the sarcopha-
                                                                                                                                  gus began with a mechanical process using soft bristles; then, the loosened dirt was
                                                                                                                                  removed using a vacuum cleaner, and a range of different sized and textured brushes
                                                                                                                                  adopted, according to the state of the existing quantity and degree of hardness of the
                                                                                                                                  calcinations, (e.g. using soft, fiberglass brushes) (Figure 9A and 9B).


                                                                                       228
   4.2.2. Chemical cleaning

     The use of chemicals for cleaning is minimized to protect the sarcophagus from
any damage that may be caused by their use, since chemical cleaning and its soluble
products are difficult to control and may cause future damage to the lead; the toxic
characteristics of such chemicals, moreover, could affect the restorer who employs
them. The chemical cleaning included the removal of calcinations produced by rust
products. The sarcophagus was thoroughly cleaned and the rust products, suspended
dust, and calcined and strong deposits, were removed using dental instruments, some-
times applying alcohol and turpentine in a ratio of (1 : 1) and to help in the eradication
of fungus, and sometimes EDTA (ethylene diamine tetra-acetic acid) in a low concen-
tration (10%) [13] (Figure 9C).




Figure 9. Mechanical cleaning; A) hair detangler brush; B) applicator brush; C) toothbrush for
chemical cleaning of the sarcophagus.


   4.3. Consolidation

    Due to a large number of cracks, gaps, and missing parts on the sarcophagus, a
decision was made to strengthen it with an inner box of Plexiglass. The same idea was




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
applied to the lead sarcophagus at the Jordanian Heritage Museum at Yarmouk Uni-
versity, where it proved to be effective even after several years. In the application, the
interior of the sarcophagus body is reinforced by using Plexiglass panels as a support-
ing inner box, with a thickness of (5mm) for each of the four sides. A binder made of
Paraloid B72, which can resist high temperatures, was used in a concentration of 20%
and the thermoplastic resin transparence of the Paraloid falls within the limits of inter-
national restoration charters [9]. The plexiglass panels were scratched with a sharp
metal tool, such as nails, to ensure the bonding of the parts. Plexiglass plate was used
because it is chemically inert, strong and transparent, and resistant to deterioration
factors, such as ultraviolet radiation and polluting agents. The internal box, made of
plexiglass is equal in size to the length and width of the sarcophagus so that it helps in
the reinforcement and the process of filling the gaps for the missing parts. Iron vises
and wooden planks were used to assist in the adhesion process.


   4.4. Fixing the broken and missing parts

    Because of the presence of many broken and detached elements from the sar-
cophagus, the process of fixing these parts using Paraloid (B72) glue in a concentra-
tion of 20% was carried out as a solution and the pieces properly positioned. Every-
thing was then assembled with the new supporting holder made of plastic glass, used
as an inner box for the sarcophagus body (Figure 10 A-F).


                                                                                                 229
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine




                                                                                                                                  Figure 10. A) Plexiglass panel after it is fixed onto the side of the sarcophagus as a support ele-
                                                                                                                                  ment (skeleton); B) and C) rectifying the sarcophagus and positioning it in the new holder; D) and
                                                                                                                                  E) joining the sarcophagus sides to each other on the plexiglass sheet by means of iron vises and
                                                                                                                                  wooden panels; F) fixing the smallest side of the sarcophagus to the plexiglass; the missing parts
                                                                                                                                  are visible from inside, thereby fulfilling UNESCO conservation requirements.


                                                                                                                                      4.5. Completing and filling the missing parts

                                                                                                                                      The process for treating the missing parts, the gaps, and cracks was then carried
                                                                                                                                  out. This involved using natural substances, such as bees’ honey wax and 5% Coloph-
                                                                                                                                  ony. The Colophony gum is added to the beeswax to increase its hardness and to con-
                                                                                                                                  trol the formation process [15]. Honey wax was selected for this purpose since it is
                                                                                                                                  chemically inert and does not react with the lead. Also, it is easy to apply and shape
                                                                                                                                  and refine and color. During casting, the wax is reinforced using flax yarn fibers to in-
                                                                                                                                  tensify the color, so as to resemble the original color of the sarcophagus’ lead surface
                                                                                                                                  using natural oxides and to achieve harmony with the original appearance of the sar-
                                                                                                                                  cophagus (Figure 11 A-H).


                                                                                        230
    4.5.1. Preparation of the materials

    The honey wax was put on a flame source until it melted, then the colophony was
added after it had been powdered and mixed with 5% hydrogen peroxide to fit and
match the color of the sarcophagus; it was then applied and used to cast and fill in the
missing parts in the new Plexiglass element [9]. Wax is used when it is warm, and melts
at 68 °C; at this temperature the colophony is mixed with the wax to increase its hard-
ness but is still easy to shape because the addition of the colophony increases the de-
gree of the melting point and needs to be prepared very precisely, usually by an expe-
rienced person. After completing the missing parts, the excess wax was removed with
gasoline as an organic solvent, as well as the outer surface of the entire sarcophagus.


    4.5.2. Completing the missing decorative unit

     Due to the loss of a large part of the edges of the sarcophagus cover with deco-
rative elements, a clone of one of the existing decorative items on the cover was
made; the cloned unit was then installed in place of the missing part [9]. The process
of cloning involved making a negative mold form of Parisian gypsum and then a pos-
itive one. Once ready, the wax with the colophony was poured into the mold to form the
decoration in the same hue as the wax used in the completion process. It was then
installed in place of the missing unit. Parts of the crucifix (Figure 8B and C) and the
missing tab with the cover of the sarcophagus were also completed with wax [15]
(Figure 11A-I).




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 11. A) and B) the side of the sarcophagus before and after completion; C) and D) gaps and
cracks in the sarcophagus base before and after completion; E) scratching the plexiglass to in-
crease cohesion with the wax; F) sarcophagus cover while using linen fiber on the plexiglass to
increase cohesion with the wax; G) and H) scratching the initial layer of wax in preparation for
casting a second layer before and after treatment; I) mold and decorative cloning unit.


                                                                                                   231
                                                                                                                                      4.6. Stabilization and coating
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine




                                                                                                                                      At the end of the restoration and completion processes, reinforcement and insula-
                                                                                                                                  tion coating substances were applied over the entire archeological sarcophagus, so
                                                                                                                                  the body of the sarcophagus was isolated from the surrounding environmental condi-
                                                                                                                                  tions and damaging factors. The corrosion on the surface of the sarcophagus was pro-
                                                                                                                                  tected with a benzotriazole solution in ethanol with a 5% concentration (for stabiliza-
                                                                                                                                  tion) [16]; it was then coated with B72 using a 5% concentration [9].


                                                                                                                                      4.7. Museum exhibition

                                                                                                                                      Protecting and preserving the lead sarcophagus was done by controlling the sur-
                                                                                                                                  rounding environmental conditions trying to remove the various factors that could dam-
                                                                                                                                  age the sarcophagus and taking precautions to prevent any negative impact on it, so
                                                                                                                                  the sarcophagus was exhibited inside a special glass cabinet in Jerash Museum [9].
                                                                                                                                  The glass cabinet was designed to be higher than the body of the sarcophagus by about
                                                                                                                                  8 cm and carry the weight of the cover as well as preventing it from touching the body.
                                                                                                                                  The base was also designed with a shorter length than that of the sarcophagus by about
                                                                                                                                  10 cm and a width of less than 8 cm so that it could be placed under the body for the
                                                                                                                                  final display of the sarcophagus. The sarcophagus was exhibited in the middle of the
                                                                                                                                  hall of the Museum of the Jerash Archaeology Directorate, after selecting the appropri-
                                                                                                                                  ate place inside the museum building and displayed in the transparent glass cabinet
                                                                                                                                  (1 cm thickness) designed to surround the sarcophagus on all sides to isolate it from
                                                                                                                                  the external environment and prevent visitors from touching it. A base made of natural
                                                                                                                                  stone was placed under the sarcophagus with a height of 15 cm, a length of 250 cm,
                                                                                                                                  and a width of 100 cm, so it did not touch the ground, thus preventing moisture from
                                                                                                                                  reaching it, and making it easier for visitors to the museum to view it on all sides (Fig-
                                                                                                                                  ure 12A, B, C). A wooden box-shaped base was also designed, painted and insulated
                                                                                                                                  to carry the sarcophagus (Figure 13B); it was then placed inside the glass case.




                                                                                                                                  Figure 12. A) plexiglass supports for the sarcophagus sides; B) decorative cloning unit after in-
                                                                                                                                  stalling it on the sarcophagus cover; C) closing tongue of sarcophagus on one of the short sides.


                                                                                             232
Figure 13 A) Final appearance of the sarcophagus before transferring it to be exhibited in the mu-
seum; B) final appearance of the sarcophagus on the stone base while on display in the hall of
the Jerash Archaeological Museum.


    4.8. Exhibition and storage conditions

    Museum officials were instructed to monitor and preserve the appropriate museum
environment to exhibit the sarcophagus in, where it is preferable to maintain a level of
relative humidity of 25-30% and a temperature in the range of 20-22 °C to reduce the
effects that cause metals to deteriorate and to discourage the growth of living organ-
isms. The lighting must not be more than 200 lux to be suitable for metals, especially
lead (Figure 13 A and B).


    5. Discussion

     The causes of lead corrosion are now largely known. During the last decades,
great efforts have been made to develop suitable methods and procedures for the sta-




                                                                                                       CONSERVATION SCIENCE IN CULTURAL HERITAGE
bilization of lead objects. These aim on the one hand to eliminate corrosive agents
from the environment of the lead object and, on the other hand, to stabilize objects al-
ready affected by active corrosion factors with suitable conservative methods [6]. Lead
metal was used in many applications in ancient times because of its high density and
ease of casting due to its low melting point [17]. To correctly apply the principles of Cor-
rosion Science to the conservation of metal heritage objects, each specific metal or al-
loy, construction technique, and particular corrosion problem encountered in a museum,
outdoors, or in an archaeological setting should be carefully considered [14]. Corrosion
processes vary depending on the metal or alloy, and this consequently affects the pro-
tective actions needed for the materials [16]. After the initial inspection of this sarcoph-
agus and due to the damage caused by inappropriate transport, storage, and unsuitable
conservation conditions, the sarcophagus was in urgent need of maintenance and res-
toration, where it was found without any previous restoration.
     Work on the sarcophagus was documented before, during and after treatments. To
start with, the damage and conservation state were scientifically identified and record-
ed; this was then followed by a description of the various stages of the work.
     Examinations conducted on lead samples of the sarcophagus by optical micro-
scope, stereo microscope, and scanning electron microscope indicated that there was
an irregularity in the surface due to the burial conditions of the coffin in the soil, and the
loads and stresses it had been subjected to in the soil before it was found, discovered
and transferred to the Jerash Museum storage space. Examinations also revealed the


                                                                                                     233
                                                                                                                                  presence of a network of fine deep cracks. Layers of corrosion appear in different col-
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine



                                                                                                                                  ors on the surface and inside the cracks and twist haphazardly with the lead metal in the
                                                                                                                                  sarcophagus. In addition, the presence of corrosion products on the surface of the lead
                                                                                                                                  metal interact with the dust and soil particles attached to the surface of the lead metal.
                                                                                                                                      The analyses conducted to identify the composition of the sarcophagus using the
                                                                                                                                  EDX unit attached to the scanning electron microscope and X-ray fluorescence, showed
                                                                                                                                  the presence of lead was found in a ratio between 97% and 98%. In addition, small pro-
                                                                                                                                  portions of oxygen, calcium, iron, carbon, silicon, and aluminum were found in the sam-
                                                                                                                                  ples. Iridium, one of the rare earth elements, was also shown in the analysis by X-ray flu-
                                                                                                                                  orescence in a very small percentage. This is considered an indication of the presence of
                                                                                                                                  some impurities mixed with the lead metal used for the sarcophagus [15]. It also shows
                                                                                                                                  the presence of some minerals from the burial soil components mixed with the metal lead
                                                                                                                                  [18]. The analysis by X-ray diffraction to identify the compounds in the sarcophagus re-
                                                                                                                                  vealed the presence of graphite (C), lead (Pb), litharge (PbO), cerussite PbCO3 and hy-
                                                                                                                                  drocerussite 2PbCO3.Pb (OH)2. The findings indicate that the sarcophagus was formed
                                                                                                                                  from lead metal that contained some impurities from other metals. On the other hand,
                                                                                                                                  some minerals appeared to represent corrosion products of lead metal as well as being
                                                                                                                                  the result of interaction with the metal components in the burial soil; furthermore, the
                                                                                                                                  presence of excess salts in the soil poses major problems of corrosion [19]. The pres-
                                                                                                                                  ence of a dense layer of lead carbonate (PbCO3) as one of the products of the rust of het-
                                                                                                                                  erogeneous lead, accompanied by an increase in volume [18], was confirmed after the
                                                                                                                                  analysis of a sample of the sarcophagus using X-Ray fluorescence (XRF). On most parts
                                                                                                                                  of the sarcophagus unstable lead oxide (PbO) layers can be seen; and many cracks,
                                                                                                                                  fractures, and spills are scattered in many places on the body of the sarcophagus.
                                                                                                                                      The loss of some parts of the sarcophagus was a major problem, as well as the de-
                                                                                                                                  struction and deformation of the sides of the sarcophagus. There was a thin protective
                                                                                                                                  layer of lead oxide (PbO), a patina over the metal in the atmosphere [20]. Sometimes
                                                                                                                                  the patina layer contains a darker coloured lead sulfate. Another thin white layer was
                                                                                                                                  found on the surface of the sarcophagus. Lead artifacts from land sites are often coat-
                                                                                                                                  ed with cerussite PbCO3 or hydrocerussite 2PbCO3.Pb (OH)2 [13]. Depending on the
                                                                                                                                  burial site and environmental factors, the amounts of lead oxides (PbO and PbO2) vary
                                                                                                                                  [19-20]. Lead is generally corrosion resistant. Despite a commonly low electrochemi-
                                                                                                                                  cal potential (-0.12 V), the patina layer will form a stable, adherent layer, and protect
                                                                                                                                  the metal from corrosion if the environment is not polluted or unsuitable.
                                                                                                                                      A white corrosion layer of hydrocerussite (Pb3(CO3)2(OH)2) occurs in alkaline soils
                                                                                                                                  containing dissolved carbonates. In alkaline soils where carbonates are sparse, lead cor-
                                                                                                                                  rodes into brown, reddened oxides with few carbonates, if any, and traces of lead metal
                                                                                                                                  may remain in the cracked corrosion crust [17]. Lead can react with the chloride and sul-
                                                                                                                                  fur impurities, and oxygen and moisture, which affect the composition of the corrosion
                                                                                                                                  layer of the archaeological artifacts [19]. A weak corrosion layer of lead can be destroyed
                                                                                                                                  by handling. Moreover, a dry environment after excavation may lead to decay, collapse,
                                                                                                                                  and deformation of the lead archaeological artifacts [21]. Lead is generally sensitive to
                                                                                                                                  the presence of organic acids, mainly acetic acid (CH3COOH), formic acid (HCOOH),
                                                                                                                                  and formaldehyde (CH2O). Lead’s sensitivity to acid is such that it has often been used
                                                                                                                                  as a passive indicator of the concentration of the pollutant in a specific area [22]. These
                                                                                                                                  organic acids or their starting materials can be released into the environment by a vari-
                                                                                                                                  ety of materials, such as wood and wood products, paints, adhesives, or textiles.
                                                                                                                                      The result of an accelerated corrosion test illustrates the corrosive effect of various
                                                                                                                                  materials on lead [21]. The pollutants most frequently mentioned in connection with ac-
                                                                                                                                  tive lead corrosion in museums are formaldehyde (methanol), formic acid, and acetic


                                                                                         234
acid. When lead is attacked by these acids, it causes the formation of salts, which are
then transformed into basic lead carbonates [18]. If these conditions prevail in a spe-
cific deposition, lead is unlikely to have the ability to survive for more than half a cen-
tury of burial. In contrast, lead is resistant to corrosion by seawater and cretaceous
soil. The corrosion crust often retains the topographical details of the original surface.
However, this crust sometimes deforms, and the remaining details are only found in
the center of the underlying metal where it is able to withstand conditions for a longer
period. The corrosion penetrates the level of the original surface inside the deformed
lead sheets and the corrosion particles can go deeply into the pores and cracks; the
lead parts of the body therefore seem more fragile than they appear [23]. Treatment,
conservation, and restoration of the sarcophagus were performed by adjusting the tor-
sion, which was one of the most challenging treatment operations and took a great
deal of time and effort; care was also taken with the existing decoration in order not to
distort its appearance during this process [15]. The mechanical cleaning process is the
most accurate, and controllable of the results, and the safest method, as it does not re-
quire the addition or removal of any materials.
     The goal was to remove the dirt and deterioration products that distorted the overall
shape of the sarcophagus, namely, dust, foreign objects, and rust products, by breaking
the link between them and the surface of the sarcophagus. This was followed by a chem-
ical cleaning process and included removal of the calcification from the rust products that
the mechanical cleaning process was unable to remove [23]. The sarcophagus is sup-
ported by an inner box made of 5 mm thick plexiglass sheets. Plexiglass was also used
to make a skeleton of the sarcophagus to fix the broken parts by setting them with the in-
ner glass holder of plastic glass, using natural materials such as beeswax resin coloph-
ony, which was added to the wax to increase rigidity and to control the formation process;
this is because, as it is a constant chemical substance which does not react with lead, it
is easy to apply, model, refine and color [24]. The wax was also supported during the
casting, using fiber from flax yarn to further increase its rigidity and cohesion — the bees-
wax was colored using natural oxides to achieve harmony with the original sarcophagus




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
color. A decorative unit from one of the edges of the sarcophagus was cloned to replace
another that was lost and then installed in its original place by creating a mold of wax with
the same degree of color as the sarcophagus [15]. To conserve and protect the sarcoph-
agus, benzotriazole (C6H5N3) with a concentration of 5% was used, and then Paraloid
(B72) with a (5%) concentration was used as a final protective coating [25]. Moreover, af-
ter completion of the maintenance and restoration, all actions were documented, and the
final transfer procedures were recorded by photographing and drawing them, all carried
out at Jerash Archeology Museum. The sarcophagus was displayed in a special glass
cabinet to protect it from adverse environmental factors. The museum staff was instruct-
ed to regulate and maintain a relative humidity of 25-30 %, as well as a temperature of
18-22 Cº, to reduce air moisture content, which causes the destruction of metals and
helps the growth of living organisms, and monitor the lighting, which must not exceed
200 lux to be suitable for metals, especially lead.


   6. Conclusion

    The lead sarcophagus was used for burial in the Byzantine era. It was damaged by
the impact of being buried in the soil and the pressure it was exposed to inside the soil
layers. After its discovery at the excavation site, the sarcophagus was improperly
stored in the Jerash Museum warehouse, which caused further damage. It was then


                                                                                                235
                                                                                                                                  transported to the restoration laboratory, and examinations and analyses were con-
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine



                                                                                                                                  ducted which showed the presence of various deterioration factors, for example, the
                                                                                                                                  presence of cracks, surface erosion, distortion and morphological deformation, in ad-
                                                                                                                                  dition to the formation of layers of corrosion mixed with grains of the burial soil. The
                                                                                                                                  heterogeneous corrosion layers included C, Pb, PbCO3, PbO, and 2PbCO3.Pb(OH)2.
                                                                                                                                  Treatment, restoration, and conservation processes for the sarcophagus were carried
                                                                                                                                  out. They included mechanical and chemical cleaning, in addition to consolidation, fix-
                                                                                                                                  ing the broken and detached parts, completing and filling the missing parts, reproduc-
                                                                                                                                  ing a missing decorative unit, stabilization, and coating. The stabilization of the sarcoph-
                                                                                                                                  agus was accomplished by brushing it with a 3% benzotriazole solution, which formed
                                                                                                                                  a thin film on the surface of the artifact to seal the chloride ions with moisture and oxy-
                                                                                                                                  gen. Finally, to protect the artifact from atmospheric humidity and corrosive ions, it was
                                                                                                                                  coated with a 5% solution of Paraloid B-72. Finally, conditions for its display in the mu-
                                                                                                                                  seum exhibition and storage conditions were adjusted to maintain a healthy environ-
                                                                                                                                  ment for its continued preservation.


                                                                                                                                        Acknowledgments

                                                                                                                                     We would like to thank and express our gratitude to the General Manager of the
                                                                                                                                  Department of Antiquities at Jerash museum, and our colleagues there for their coop-
                                                                                                                                  eration. We thank them all, and all those who helped in accomplishing this work


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   Biographical notes

    Wassef Al Sekhaneh, (Ph.D. Material Science and Conservation), (Ph.D. Cultural
Anthropology), is presently a member of the Department of Conservation and Manage-
ment of Cultural Resources in the Faculty of Archaeology and a member of the Facul-
ty of Pharmacy at Yarmouk University (Jordan); he is skilled in nanomaterials, analyti-
cal diagnostics of archaeological materials, and specialized in experimental physics,


                                                                                              237
                                                                                                                                  conservation science, nuclear magnetic resonance spectroscopy (NMR), Raman and
W. Al Sekhaneh, G.A. Mahmoud, A. Elserogy, B. Fawwaz al-Boorini - Deterioration and conservation of an archaeological Byzantine



                                                                                                                                  X-Ray spectroscopy, and Fourier transform infrared, both conventional (FTIR) and
                                                                                                                                  synchrotron radiation (SR-FTIR).

                                                                                                                                      Gehan Adel Mahmoud has worked as a lecturer of restoration and conservation
                                                                                                                                  of antiquities in the Conservation Department at the Faculty of Archeology, Luxor Uni-
                                                                                                                                  versity, from 2017 until now. She holds a master’s degree and a doctorate from the
                                                                                                                                  Faculty of Archeology, Cairo University, in the conservation of metal objects. She worked
                                                                                                                                  in the Engineering Consulting Department, Department of Antiquities Restoration and
                                                                                                                                  Maintenance, the Arab Contractors Company, in the restoration and maintenance of
                                                                                                                                  antiquities for twenty years (1997 to 2017). She has participated in many local and in-
                                                                                                                                  ternational conferences and has published numerous research papers on the resto-
                                                                                                                                  ration and conservation of gilded silver, bronze, iron, and copper metallic antiquities in
                                                                                                                                  journals with impact factors, locally.

                                                                                                                                       Abdelrahman Elserogy, Ph.D. in Investigation, Restoration and Conservation of
                                                                                                                                  oil painting with Honors 2002, Department of Restoration, Faculty of Archaeology, Cai-
                                                                                                                                  ro University, Egypt. He has a Diploma in Restoration of the Palazzo Spinelli Institute,
                                                                                                                                  Florence, Italy. He has worked as a Restoration Conservator in the conservation field
                                                                                                                                  in lower Egyptian museums and in the Egyptian organization of antiquities (1988 -1995);
                                                                                                                                  he was head of the conservation departments in the lower Egyptian museums of Sinai
                                                                                                                                  and the Northern Coast Egypt, the Egyptian organization of antiquities (1995-2003); he
                                                                                                                                  was Director of the Conservation Departments in the lower Egyptian museums, Sinai
                                                                                                                                  and Northern Coast Egypt, Egyptian organization of antiquities (2003-2005). He is
                                                                                                                                  currently Professor in the Restoration Department at the Faculty of Archaeology of
                                                                                                                                  Fayuom University, Egypt. He also worked as a Professor in the Department of Con-
                                                                                                                                  servation and Management of Cultural Resources, Faculty of Archaeology and Anthro-
                                                                                                                                  pology, Yarmouk University, Jordan.

                                                                                                                                      Bilal Fawwaz Muhammad Al-Boorini, MA in Conservation of Cultural heritage at
                                                                                                                                  the Jordanian Department of Antiquities, Jordan. He has participated in many local and
                                                                                                                                  international conferences. He has worked as an inspector at Jerash Archaeological
                                                                                                                                  Museum in Jordan and department of Antiquities in Amman, Jordan.


                                                                                                                                     Summary

                                                                                                                                      The research looks at a Byzantine sarcophagus made of lead, found in Jerash
                                                                                                                                  (Gerasa), Jordan, kept in the warehouse of the Jerash Museum under No.1824. The
                                                                                                                                  sarcophagus was exposed to unsuitable storage conditions that caused severe dam-
                                                                                                                                  age. Examination by optical stereomicroscope and scanning electron microscope re-
                                                                                                                                  vealed that the sarcophagus suffered from various deterioration phenomena, for ex-
                                                                                                                                  ample, the presence of corrosion layers, folds and various cracks. The analysis of the
                                                                                                                                  sarcophagus by the EDX unit attached to a scanning electron microscope and x-ray
                                                                                                                                  fluorescence, showed that it contained 98% lead, in addition to a very small percent-
                                                                                                                                  age of other elements such as iron, aluminum, sodium, silicon, and carbon. Analysis
                                                                                                                                  by X-ray diffraction revealed that the sarcophagus also contained minerals, which in-
                                                                                                                                  cluded Graphite (C), Lead (Pb), Litharge (PbO), Cerussite PbCO3, Hydrocerussite
                                                                                                                                  2PbCO3.Pb (OH)2. The treatment, restoration, and maintenance stages of the lead sar-


                                                                                          238
cophagus were then carried out and were followed by mechanical and chemical clean-
ing and straightening of the deformed areas. The missing parts were also integrated,
and the four sides of the sarcophagus were assembled using plexiglass as a support
material. Treatment with a benzotriazole solution in ethanol with a concentration of 5%,
and with Paraloid B72, also with a concentration of 5% were carried out (coating). The
sarcophagus cover was also completely repaired. After completion of the treatment,
restoration, and conservation processes of the sarcophagus, a transparent glass cab-
inet of 1 cm thick was designed for its display inside the Jerash Museum in an environ-
ment with a relative humidity of 25-30% and temperature of 20-22 °C.


   Riassunto

     La ricerca prende in esame un sarcofago bizantino in piombo, rinvenuto a Jerash
(Gerasa), in Giordania, conservato nel magazzino del Museo di Jerash con il n. 1824.
Il sarcofago è stato esposto a condizioni di conservazione non idonee che hanno cau-
sato gravi danni. L’esame allo stereomicroscopio ottico e al microscopio elettronico a
scansione ha rivelato che il sarcofago soffriva di vari fenomeni di deterioramento, ad
esempio erano presenti strati di corrosione, pieghe e crepe varie. L’analisi del sarcofa-
go da parte dell’unità EDX collegata a un microscopio elettronico a scansione e fluore-
scenza a raggi X, ha mostrato che conteneva il 98% di piombo, oltre a una piccolissima
percentuale di altri elementi come ferro, alluminio, sodio, silicio e carbonio. L’analisi me-
diante diffrazione di raggi X ha rivelato che il sarcofago conteneva anche minerali, che
includevano grafite (C), piombo (Pb), litargio (PbO), cerussite PbCO3, idrocerussite
2PbCO3.Pb (OH)2. Sono state quindi eseguite le fasi di restauro e manutenzione del
sarcofago in piombo, seguite da pulitura meccanica e chimica e raddrizzatura delle
zone deformate. Sono state integrate anche le parti mancanti e i quattro lati del sarco-
fago sono stati assemblati utilizzando il plexiglass come materiale di supporto. Sono




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
stati effettuati trattamenti con una soluzione di benzotriazolo in etanolo alla concentra-
zione del 5%, e con Paraloid B72, anch’esso alla concentrazione del 5% (coating). An-
che la copertura del sarcofago è stata completamente restaurata. Al termine degli inter-
venti di restauro e conservazione del sarcofago, è stata progettata una teca in vetro
trasparente dello spessore di 1 cm per la sua esposizione, all’interno del Museo di
Jerash, in un ambiente con umidità relativa del 25-30% e temperatura di 20-22 °C.




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