ÇATALHÖYÜK 2003 ARCHIVE REPORT

CONSERVATION

Brigid Gallagher

With Contributions by Ina St George, Steve Miller and Lucy Skinner

Abstract

Artefact and site conservation entered a new phase during the 7 week 2003 season with the introduction of new team leaders Liz Pye and Dean Sully from University College London (UCL). Students, Ina St George, Lucy Skinner and Steve Miller from the university conducted placements at the site during July, whilst Brigid Gallagher from Cardiff University, returned as conservator on July 23 and stayed until the end of the season leaving on August 19th.

As well as object conservation the work conducted over the season included environmental monitoring programmes of the site; excavation areas under cover and the on-site storage depots (Lucy Skinner). A condition survey of material previously excavated and in storage (Steve Miller). Materials research working with plasters and pigment on site to address best lifting methods, making and utilising possible recipes in the experimental house, and sampling for analytical investigation on composition (Ina St George). Ongoing conservation concerns continued with maintenance of currently exposed mud brick architecture (Building 5, Ina St George) and their plasters (South Area, Building 17, Brigid Gallagher).

Özet

7 haftalik 2003 sezonu sirasinda, University College London’dan gelen yeni ekip baskanlari Liz Pye ve Dean Sully’nin katilimiyla buluntu ve saha konservasyonu yeni bir asamaya girmistir. Ayni üniversitenin ögrencilerinden Ina St Geogre, Lucy Skinner ve Steve Miller, temmuz ayinda sahada çesitli yerlestirmeler gerçeklestirirken, Cardiff Üniversitesi’nden Brigid Gallagher 23 temmuzda konservatör olarak sahaya geri dönmüs ve sezonun sonuna kadar kalarak 19 Agustos’ta ayrilmistir.

Nesne konservasyonunun yani sira, sezon boyunca yürütülen çalismalar sunlardir: Yerlesme üzerinde çevresel gözleme programlari, çati altindaki kazi alanlari ve yerlesmedeki depolama alanlari (Lucy Skinner). Önceki kazilarda ele geçmis ve depolanmis materyalin durum kontrolü (Steve Miller). En iyi kaldirma yöntemini arastirmaya yönelik olarak siva ve pigmentler üzerinde materyal arastirmasi, deneysel evde olasi yeni tariflerin yapilmasi ve uygulanmasi, kompozisyon üzerinde analitik incelemeye yönelik örneklendirme (Ina St Geogre). Ayrica, ortaya çikarilan kerpiç mimari (5 nolu bina, Ina St George) ve sivalari (Güney çatisi, 17 nolu mekan, Brigid Gallagher) ile ilgili süregelen konservasyon çalismalarina devam edildi.

2003 Season

All objects or materials that came to the conservation laboratory were recorded in the project database. Before and after photos were taken, some on a site digital camera, which were filed into the project database, and some on a digital camera returning to UCL. These are to be amalgamated. Extended reports from individual projects were produced, and a copy will be filed on site for future reference. 96 objects or materials were recorded on the 2003 Object Conservation Log. This does not include large scale, on site, site conservation that was conducted, nor projects undertaken to aid other archaeologists, such as material analysis. Some objects and samples have been stored for analysis in the 2004 season. These have been entered into the finds log and stored in the Finds depot. Samples taken that have not been analysed have been entered into the conservation log and are stored in a newly created crate in the Finds depot marked ‘For Conservation 2004’ when they will become part of a sample archive with view to future study.

During the dates, 5-10 July, Liz Pye and Dean Sully visited the site to observe and review on-site conservation facilities and procedures. As part of this process, various specialists were visited to ascertain requirements of the conservation facility, and address problems that have previously arisen regarding the relationship between archaeologists and conservators. An assessment was made of the present roles that conservation plays at the site, and what future roles and procedures can be implemented. Some of these were initiated during the 2003 season, including:

A condition survey of material previously excavated and in storage (Steve Miller).

1. A first aid for finds and artefact-lifting kit designed for use by field archaeologists during unforeseen conservator absence. This also included research into best methods of back filling areas of excavation at the end of season, which field archaeologists raised as a particular concern. Other areas of concern raised was training in correct sampling procedures and adhesion use for ceramic reconstruction.

2. Environmental monitoring of specific areas of the site including the South Area, Building 5, the Finds Depot, the Conservation Laboratory and the Experimental House (Lucy Skinner). The onsite custodians have been trained to continue this procedure during the off season periods to gain an insight into environmental conditions all year round, and gain greater understanding of the potential effect this may have on in situ architecture and stored artefacts.

Materials research with Ina St George working with plasters and pigment on site to address best lifting methods, making and utilising possible recipes in the Experimental House, and sampling for analytical investigation on composition. Lucy Skinner addressed bone and best facing and lifting techniques, and tested a range of consolidants on animal bone to observe colour change and physical properties imparted to the material. Japanese tissue paper and Polyvinyl alcohol were found to be good for facing and lifting bone, and Mowilith for consolidation.

Aside from specific projects being implemented, ongoing conservation concerns continued with maintenance of currently exposed mud brick architecture (Building 5, Ina St George) and their plasters (South Area, Building 17, Brigid Gallagher). This was particularly prevalent in the South Area with the erection of a shelter which covered all excavations in the area to date, including the Summit Area. To enable through-flow of air through the shelter, all sides except the north-east corner were removed (part of the construction plan of the shelter), however during August temperatures of 45? degrees was recorded, with 100% humidity. The effect this has on materials, both archaeological and used in conservation treatment, required addressing. The result was, that any conservation of exposed plasters and pigments in the South Area was primarily conducted early in the morning or in the evening, with a drop in temperature, to aid curing of consolidants, adhesives and coatings used. Due to the lack of air movement through the area, evaporation of solvents used in these materials was extremely slow, effecting setting rates, making the reattachment and consolidation of plaster fragments difficult. Support materials were necessary to aid attachment. Water based consolidants and adhesives were attempted; however the water content contributed to swelling of the smectite clays used in the plaster. Caused partly by high humidity in the shelter; loss of mechanical strength and increased load on the plaster caused it to pull it away in from the mud brick.

Building 17
Sandbags and geotextile covering the previously excavated buildings and spaces were cleared by local work men during the 2003 season. The aim was to clean up these sections in preparation for a 3-D digital scan of the area. During the 1999 season when the space was excavated, red pigment was observed in patches on the plaster and the decision made not to continue excavation of the plasters until the archaeologists had the stratigraphy in phase. The north end of the west-facing wall was the only area to have its plasters exposed. Seen in Fig. 64, there is a decorative rib, horizontal with the ground surface. Revealing the wall in 2003, the plasters were wet and in some places delaminating. This is likely to have been exacerbated by the plastic sandbags disallowing air exchange between the wall and the outside environment even though geotextile was in place to facilitate this. During the 2003, previous work and procedures set out by Frank Matero and his team in the Çatalhöyük 1999 Archive Report: Site Conservation Report were attempted. Due to the change in environmental conditions caused by the new South Area shelter, some of these procedures required revising. Initially, consolidation of intralayer plaster delamination and plaster detachment from the preparatory layer and mud brick substrate followed Matero’s procedures (1999 archive report: site conservation), proving in part unsuccessful due to the wet, heavy nature of the plaster, causing further damage to the architectural features. The decision was made to monitor the reaction of the plasters with the environment, and treat accordingly. The insertion of nylon or stainless steel dowels into large fragments of plasters that were detaching from the substrate was considered.

Figure 64: Plaster exposed at the north end of west facing wall in Building 17

Methods used: In areas where the plaster dried, cracks <1mm were consolidated with 5% w/v Paraloid B72 (methyl methacrylate co-polymer) with acetone, and plaster readhered with 15-20% w/v Paraloid B72 with acetone. Drying was allowed to occur over a three week period to the end of the season. In damp areas water based 5% and 10% Primal AC33 (acrylic emulsion) were sprayed into surface, focussing on cracked areas and pressed into place. In cracks 1-3mm in width, 10% Primal A33 was mixed with carboxy methyl cellulose (a thickening agent (CMC)) and applied with syringe. In cracks 3-5mm in width, primarily at the top edge of the existing plasters in the space, and previously gap filled by Matero in 1999 with 10% Rhoplex AC33 in water, glass micro balloons, hydraulic lime and sand mix (1:4:4) mix, these were removed, and replaced with the same mixture. The mud brick substrate and plasters were pre-consolidated with 5% Primal AC33, and the Rhoplex replaced with Primal. Given the length of plaster exposure and its interaction with the new environment, the plasters were covered at the end of the season with geotextile and pearlite bags, and assessment of the procedures used in the 2003 season will occur, with conservation treatment continued.

Building 2, Space 117
During sandbag clearing of Building 2 by local workmen, plaster on the south facing wall detached, exposing within the plaster layers part of a wall painting (See Fig. 36). It consisted of an orange back ground with white pigmented spots, with some fine black outlines. There was no intention to fully excavate and lift the painting in the 2003 season due to being found in the last week of the season, and the instability of the wall on which it is located. Structural shoring will be required prior to work commencing on the painting, both for the health of the painting and safety of the people working on it. Given the unknown effect the south shelter was having on the archaeology, and the response of usual conservation procedures previously set out, monitoring of the painting occurred initially without treatment. The pigment appeared stable with little or no delamination of the surface. The plaster did not dry in the week it was exposed. Before covering at the end of season, the pigment was consolidated with 3% and 5% w/v Paraloid B72 in 70/30 acetone/toluene. The painting was covered with Hollytex? geotextile, heavy geotextile and pearlite bags until the 2004 season. Strategy for its treatment will need to be considered in consultation with archaeologists due to the structural instability of the wall that it is located on.

Building 5
Rather than continue to conduct the usual annual maintenance work on Building 5, with replacement of gap fills, and adhesion and consolidation of plasters as set out and conducted by past conservators, Ina St George and Steve Miller, made an assessment of its present condition, which was written up as a report; and conducted intense photo documentation. In conjunction with discussions with Site Director Shahina Farid, the building was judged to be in a fairly good condition, with cracks about the edges of past gap fills indicative of minimal movement between seasons. Separation of plasters from mud brick was not recorded. In the southwest corner of the shelter, green algae caused by rainwater entering and washing down in the sections, remained a problem. As a result, routine maintenance of the building included, brushing of floors and exposed walls to remove loose debris, and evidence of insect and animal activity. Light trowelling was used on some walls. It was recommended that past conservators, F. Matero and K. Severson, and archaeological architectural conservators be consulted before further treatment is conducted.

By the end of the 2003 it was evident that the section above the main north-facing wall was crumbling at quite a rapid rate. In the past an attempt has been made to consolidate this section with a 5% or 10% Primal solution, to prevent this occurring. The result may be that this has increased the stresses and load within the soil section causing the face of the section to fall more quickly than it otherwise would. At the end of season, the section was covered with geotextile and small sand bags were made up to stack up against the section to prohibit further erosion. Structural instability of this section was evident, with fear that the archaeology yet to be excavated would collapse over the winter months.

Objects Conservation
Late Roman or Byzantine objects from the 4040 Area included an assemblage of burial goods from unit (7906), with a fiancé bead (Cons. Lab. 03.040), a glass vessel (03.041), a gold earring (03.042), two ceramic vessels (Cons. Lab. 03.043/044) (See Fig. 19), which were treated by conservation. An almost complete classical vessel, with rim missing, measuring 33cm in height was microexcavated and adhered. The Neolithic objects resulting from excavation and conservation treatment included a copper alloy armband (Cons. Lab. 03.006, See Fig. 15), where four pieces were adhered together.

The three well fired stamp seals (see above), were treated. 8805.X2 (Cons. Lab. 03.072) was representative of a leopard with spots and a tail lying over its back (See Fig. 61). The two front legs, and the head were missing. There was a simple handle with small, circular perforation. The stamp required mechanical cleaning only, with packaging in a polythene box and acid free tissue. Of the two other fired clay stamp seals recovered, both were geometric. 8813.X1 (Cons Lab. 03.075, See Fig. 59), required desalination, and was adhered together with ~20% Paraloid B72 w/v in acetone. The handle was not located. 8814.X15 (Cons. Lab. 03.084, See Fig. 60), had an irregular form and required mechanical cleaning only.

Two positive copies were made of each. The negative mould was created by wrapping cling film over the ceramic to protect it, and then, soft plasticine was pressed onto the stamp seal. A mix of molten paraffin wax and dental plaster was then poured into the plasticine moulds and allowed to dry before peeling the mould away. Also associated with the stamp seals was a very friable animal figurine. The ceramic was granular and exhibited lack of cohesion. Salt migration was causing some damage, and as a result the five fragments (part of the face and neck was not found) were desalinated, consolidated with 3%, then 5% Paraloid B72 w/v in acetone, and then adhered using ~20% Paraloid B72 w/v in acetone.

Many small beads were also found in the 4040 Area Neolithic burials. These were in a range of materials including dentalium, carnelian, and malachite (L. Skinner, microscopic examination). A complete armband, thought to be alabaster, was also excavated from a burial unit (See Fig. 14). Further analysis is required to confirm the material identification. In two burials, a bright blue pigment was lifted (Cons lab nos. 03.051, 03.071). The crumbling nature of the pigment was not consolidated, with view to future pigment identification. A range of materials or objects were bought to laboratory for possible conservation, including 3 pieces thought to be slag (Cons. Lab. No’s. 03.058, 03.059 & 03.060). Another fragment (03.057) was thought by the excavation team to be lead. This requires further examination in the 2004 season.

South Area, east end
A fragment of red painted wall plaster was sampled during excavation, and exported to the UK for analysis. An upturned base of a vessel was micro excavated in the laboratory and given two sample numbers. The ceramic was mechanically cleaned with a soft brush.

TP Area
Painted wall plaster was found, and either lifted by conservation or the field archaeologists. None was found in situ, and samples were exported to the UK for analysis. A baby’s skull from a Neolithic burial unit was consolidated prior to micro excavation and reconstruction is planned in the 2004 season. A reversible adhesive was essential for this and Paraloid B72 was used for this reason.

BACH Area
Samples of painted wall plaster were taken by Ina St George from the BACH Area and exported to the UK for analysis. A fragment of copper alloy (Cons. Lab. 03.048, Unit 8606.X3) was cleaned, treated with 3% w/v Benzotriazole (BTA) in deionised water to inhibit further corrosion. It was coated with 5% Paraloid B72 w/v in acetone.

West Mound
A worked antler was bought to the laboratory for reconstruction. The pieces were consolidated, and the fragments adhered with Paraloid B72 in acetone and toluene. The reconstruction of the full length of the tine was achieved, showing both ends to be worked. Conservation also aided the West Mound team by taking apart old joins of previously reconstructed ceramics and readhering with a smoother join. Pot fragments with organic residues adhering to surfaces were bought to the laboratory for sampling. The samples were taken ad retained in labelled glass vials and retained for future analysis.

Other Projects
With view to a display area in the South Area now the shelter has been erected, public access and areas have been roped off at the highest point of the area to the east, next to the South Summit Area. In conjunction with this Ina St George projected the “Volcano/City Plan” image as recorded by Mellarrt during the 1960’s excavations from a wall painting in the South Area (see Fig. 5). The image was painted onto a wooden panel, with support struts, facing into the shelter from the north side of the area.

The same image was used in the experimental house during continued experimentation of pigment and binder use in Neolithic wall paintings recorded on site (fig. 65). During the 2002 season, casein (milk protein) was used to bind red iron oxide pigment. This used to paint a “bird and headless people” scene onto dry plaster walls. It was evident however during the 2003 season that the pigment and binder had delaminated from the plaster due to paint shrinkage and lack of bonding with the dry plaster. A mixture of iron oxide and water was made up and used by Ina St George during the 2003 season; utilising the hygroscopic nature of the plaster, thereby creating an intrinsic bond between paint and plaster. The result of this will be recorded in the 2004 season.

Figure 65: Reconstruction in the Experimental House

Mirjana Stevanovich of the BACH team required sediments of mud brick to be discussed after flotation. Four samples of mud brick, and two samples of mortar bonding the bricks were taken from the south and western walls of Building 3, BACH Area. Results showed changes in composition, and differences in load within the wall with increased compaction with increased depth. In the south wall, iron content decreased with depth, as did organic material. The mud brick sediments were all well sorted, with no grain size change between samples. The mortar showed defined layers, suggesting a recipe was use to formulate its composition. The sample after floating had foam across the top of the water surface denoting hydrogen evolution of a calcareous deposit. The mud brick sample taken from the west wall had varying grain sizes of different composition, little iron content, plus greater porosity than south wall bricks. The mortar contained calcareous material and hydrogen evolved, moderate grain size, and least amount of compaction, and therefore porosity of all samples. Strategy and sample collection were the responsibility of M. Stevanovich, and a full report of findings was submitted to her.

Throughout the season, areas that required development and could be covered by the conservation team were identified. These included:
1. First port of call for materials identification using microscopy and spot testing. Textile fragments (Cons. Lab. 03068, 03.070, 03.087) and their associated deposits were bought to the lab for sieving and sorting to identify fabric, and composition of the deposits that may lead to information on the use of the fabric.

2. Advice centre for analytical procedures that could be used on archaeological data, such as pigment and plaster analysis.

3. Collection of residues from pottery from the West Mound team. Establishing reference collections. L. Skinners consolidated bone samples were labelled and retained in glass vials. A fragmented textile sample retained.

End of season reburial of site

4040 Area - As the main focus of the season was to define the extent of the area to be excavated and clear the over burden off the archaeology, the area was covered with sand bags (Fig. 66). An exception to this was a feature in the north east corner of 4040 where a number of burials, with as yet undetermined stratigraphic relationships were partially excavated. This pit like area was covered with geotextile, and polystyrene blocks use to take the weight off the skeleton before sand bags covered it.

South Area - Unveiling of the plaster surfaces in the South Area occurred during the last two weeks of excavation. There was inadequate time to successfully address the problem of delaminating plasters, particularly with the added problems of poor environmental conditions brought about be lack of air movement and the ability to trap heat and moisture within the shelter. At the end of season, the exposed plasters were covered up by applying a thick geotextile over the plaster, and then gently leaning sand bags against that. In Building 17, where the plaster was in poor condition, pearlite bags were laid against the plaster due to their gentle nature. The wall painting exposed during the last week of excavation was covered with a fine layer of hollytex? and then thick geotextile, followed by pearlite bags. The pigment had been consolidated using 3% Paraloid B72 w/v in acetone previously.

Figure 66: 4040 Area backfilled with sandbags

Other areas – BACH and TP Areas and the West Mound were all covered over by placing a tarpaulin, or material to that effect, and then laying sand bags down. West Mound is not planning to reopen during the 2004 season, and this method was utilised after the previous season of excavation, in 2001, and the archaeology did not appear to have suffered greatly. It was therefore repeated, however further research into this technique is advised.