ÇATALHÖYÜK 1999 ARCHIVE REPORT

Site Conservation Report

Alan Konservasyonu Raporu

Frank Matero

Frank Matero Co-Director of Site Conservation,
Lindsay Falck, Co-Director of Site Conservation,
Kent Severson, Director of Artifact Conservation;
Caitlin Moore, architect, Graduate School of Fine Arts, University of Pennsylvania;
A. Esin Kuleli, restoration architect, Directorate of Ruins and Monuments
Latif Özen, conservation scientist, Museum of Anatolian Civilizations, Ankara

Abstract

Conservation work concentrated on treating the walls and features of building 5 in the North Area so that it could be displayed to the public.

Özeti

Halka sergilenmesinin sağlanması için Kuzey Alanı duvarlarında ve mimarisinde konservasyon işlemlerine yoğunluk verilmiştir.

1 Introduction

Now in the sixth year of activity, the 1999 site conservation program at Çatalhöyük was organized around the accelerated excavation schedule in the South Area beginning in April. Lindsay Falck was responsible for the design of the two innovative shelters for the North and South Areas as well as the complex shoring required in the South Area (in conjunction with Ove Arup, Turkish Office), and Frank Matero was in charge of the retrieval, stabilization, and presentation of Building 5, North Area and the inspection and temporary treatment of Building 17, South Area. Kent Severson directed finds (artifact and ecofact) conservation including developing a system for storage and treatment documentation. Esin Kuleli, Latif Özen and Sibylla Tringham assisted in site conservation activities.

2 Building 5/North Area

During the 1998 field season a decision was made by the Turkish authorities in conjunction with the project directors to preserve and interpret Building 5 for display over the next few years. This required the development of a coordinated program of effective temporary reburial over the 1998-99 winter season, temporary and long-term mud brick and plaster stabilization, and environmental protection (shelter) and display.

2.1 Removal of reburial material from Building 5/North Area

Based on research performed at the University of Pennsylvania in 1997-98, a reburial program was installed at the close of the 1998 season by E. Kopelson to provide maximum environmental and structural protection while being easily removable. The system employed a layer of liquid water-impermeable/vapor permeable felted geo-fabric placed directly on the plaster floor with approximately 12 inches of soil fill. Plastered walls and fragile features (e.g., earthen bins) were temporarily protected by a series of stacked plastic-woven grain sacks partially filled with fine perlite and covered by water repellent canvas and woven acrylic fabric, the whole held in place by stacked bags of soil which served to retain the perlite bags and brace the earthen walls. Research and other site experiences indicated that perlite provides optimum thermal protection and vapor permeability as well as conforming support for fragile surfaces such as the multi-layered plaster surfaces. The secondary system of soil bag walls holds the perlite interface in place while providing structural support for structurally unsound walls. The entire infill was directly covered by canvas salvaged from the temporary shelter constructed during the season.

The reburial material was removed in August 1999. Soil bags were deteriorated as was expected, however most allowed whole bag removal. The canvas and acrylic coverings were in good condition and the perlite bags dry and intact. No animals took up residence in the fill material during the winter months. The walls appeared to be in excellent condition-dry and firm to the touch. Removal of the reburial materials took less than one day and required less labor than the traditional loose fill or bagged soil used in the past for filling the entire excavation.

2.2 Inspection

All large wall cracks (surface and through-wall) were measured and compared with the measurements from the preceding year. Vertical through-wall cracks were found to have opened slightly-probably a function of the walls continuing to dry long after excavation and treatment. As a result, grouted vertical cracks exhibited some separation and cracking (see below). On the other hand, treated delaminated plasters were found to be sound with no new detachments or collapses. Floors appeared damp but undamaged.

The floors were exposed for several days to allow them to dry out and harden. The fragile earthen bins in Space 157 were kept buried until time was available for their immediate re-assessment and treatment upon exposure which proved to be good.

2.3 Conservation Treatments

As initially planned, the opening of Building 5 was to proceed after the erection of the shelter; however due to technical delays in construction, the site was opened before its completion and under temporary shelter tarpaulins.. All treatments were recorded on wall elevations prepared last year by the archeological team.

2.3.1 Readhesion of delaminated plaster

Thin intralayer plaster delaminations and plaster detachment from the preparatory layer and mud brick substrate were re-adhered by injections of 10% Rhoplex AC33 acrylic emulsion. Detachments and cracks between 1-3mm in width were injected with the 10%

acrylic emulsion and Acrysol 6038A [1 part emulsion:1 part Acrysol (diluted 1:1 with water)], a polyacrylic acid manufactured by Rhom and Haas specifically for increasing acrylic emulsion viscosity. Surfaces were cleaned up immediately with water and cotton to prevent staining.

2.3.2 Injection grouting

After inspection of the walls, all open through-wall cracks and detached plasters were grouted to re-establish structural continuity. Several cracked end wall sections were seriously detached and leaning and represented the only major structural work required. Open cracks that had been previously grouted the year before were raked out and re-grouted. In most cases cotton or mortar fills were used to seal or dam cracks during grouting. In some cases, closed cell polyethylene backer rod was used to temporarily seal the larger open cracks.

Two grout formulations were used-both developed for earthen architecture by the Architectural Conservation Laboratory at the University of Pennsylvania. Structural through-wall cracks were grouted with a higher sand to microballoon ratio for additional strength. Formulations were as follows:

Large structural cracks (parts by volume): 4 parts LaFarge natural hydraulic lime, 1 part ceramic microballoons (Zeelan Z-Light Spheres G-3500), 4 parts fine local sand (passing sieve) and 10% Rhoplex AC33 acrylic emulsion (in mixing water).

Narrow wall cracks and plaster detachment (parts by volume): 4 parts LaFarge natural hydraulic lime, 4 parts ceramic microballoons (Zeelan Z-Light Spheres G-3500), 1 part local fine sand (passing sieve ) and 10% Rhoplex AC33 acrylic emulsion (in mixing water).

Both mixes were hand blended dry, sieved and mixed in a high-speed blender for 3 minutes to the consistency of ayran or heavy cream. All cracks and voids were first prepared by mechanical removal of debris and pre-wet with a 5% acrylic emulsion. Grouting was done by hand with 20-60cc syringes and a range of steel needles and cannulae (sizes 14,16,21, and 25).

2.3.3 Mortar fills (Compensation)

All grouted cracks and cracks greater than 3mm in width in the plaster and mud brick were filled with a mortar mixture of 1 part (by volume) LaFarge natural hydraulic lime and 3 parts fine grey sand. The sand provided a good neutral color, which could be color, washed afterwards to match the various surface contexts. Cracks and large disfiguring losses (not animal holes) were first dry brushed, pre-wet with water, and filled with the mortar. Deep cracks and losses were filled in stages to avoid slump and cracking. Selected cracks less than 3mm in width were filled with a finer mix of 1 part (by volume) La Farge natural hydraulic lime to 1 part glass microspheres (3M Scotchlight C15/250). Of the two fills applied, the finer fill of lime and microspheres (1:1) proved to be easier to apply and clean off and exhibited no shrinkage. The whiteness of the fill can be toned with dry pigments or site clays/silt in low concentration (not more than 10% by weight of the lime).

All fills were kept flush or slightly recessed and brush-tamped for texture and compaction. Finally all work was covered to reduce shrinkage cracking from rapid drying.

2.3.4 Plaster surface cleaning

After all remedial treatments, the dry hardened plaster surfaces were mechanically cleaned of fill still clinging to their surfaces. Wooden clay modeling tools followed by a dry stiff stencil brush worked best to flake the dry soil off the surface and on the applied horizontal ridges without deforming or inscribing the surface. The result was a distinct white plaster with its pronounced modeled surface (applied in the final phase of wall treatment). Evidence of carbon soot blackening was retained where found on the surface.

2.3.5 Aesthetic reintegration of fills

The final stage of aesthetic reintegration of the wall and mud brick surfaces involved the application of colored washes to the mortar fills to tone them to their surrounding surfaces. Ground and sieved collapsed plaster fragments and mud brick mixed with water were used for toning by brush and spray.

2.4 Shelter

Final permanent protection and display was provided by a doubled-skin canvas covered steel frame shelter with a raised wooden plank floor. This construction will remain in place for at least five years providing weather protection and interpretive information on the structure, its excavation and conservation.

3 Site Management Plan

As next year will be a study season, the majority of the planned work for 2000 is expected to go toward the development of an overall site conservation and management plan. This will be undertaken by a joint international team from the University of Pennsylvania, Istanbul Technical University and other local affiliates. An intensive site charrette is now being planned for August 2000 in conjunction with the University of Pennsylvania's summer conservation field school..