7 WOOD

7.1 EARLY TREATMENT AT THE MFA

The treatment of specific wooden objects at the MFA is largely undocumented before about 1985. An indication of earlier treatments can be gleaned from Nichols's recipe for a “cleaner for Egyptian polychromed wood” that consisted of methylene chloride, ethylene glycol, methanol, and hexane, with ammonia and soap, followed by a 50:50 solution of ammonia in water, and finally ethanol. Wood was also cleaned with a mixture of Calgon and ammonia, and often consolidated with PVAC resin, which was prepared by heating in toluene. Elmer's Glue-All was used as an adhesive and sometimes as a coating. Pearl glue was also used as an adhesive, to which thymol, plaster, whiting, or sand were added for use as a filler, the combination sometimes being referred to as “compo.” A gesso for the repair of wooden figures included whiting and hide glue (pearl glue). Soluble nylon was also prepared for use on pigmented wood during the 1970s.

The 5th Dynasty statue of Metjetjy from Saqqara (MFA 47.1455) was treated by Young after its arrival at the museum in 1948. Deep cracks in the wood were recorded (Bothmer 1948). These were filled with plaster and inpainted to make them less distracting. A number of objects entering the collection from private hands had been altered before arrival at the MFA, usually to make them more transportable. For example, an 18th Dynasty coffin lid (MFA 1988.1) with a black surface covered with an original varnish had been sawn in half; a piano hinge had been put in the middle so it could be transported or stored more easily, but unfolded for viewing. This device was subsequently removed from the coffin lid and replaced with dowels, and the losses around the middle were filled. Other coffins were substantially reduced in size, presumably to make them easier to display. In such instances, current questions of how much restoration is appropriate are difficult to resolve.

Although the application of wax in the field undoubtedly preserved many objects that would otherwise not have survived the rigors of travel, some objects clearly suffered from such treatments. Wax obscured and saturated painted surfaces, attracting dirt and causing streaking. Disrupted surfaces remained lifted, and although immobilized, they were not readhered to substrates and so remained inherently unstable. Other early treatments had additional draw-backs. Water-based materials such as gelatin sometimes stained surfaces. PVAC resins and emulsions left glossy or milky films, were difficult to remove, and contracted, pulling painted surfaces away from the substrate. Observations of damage related to the use of these materials led to the development of new fill materials and treatment methods that are less intrusive.

7.2 CURRENT APPROACHES TO TREATMENT AT THE MFA

The wet-cleaning of polychromed surfaces (often with saliva) was replaced with dry methods such as kneaded artists' erasers, then vinyl eraser crumbs. Wax was removed from surfaces using a hot spatula and tissue paper, and occasionally solvents were used to drive excess wax deeper into the wood or replaced with dilute solutions of acrylic resins in compatible solvents (Hatchfield and Koestler 1987).

In some objects treated early in the history of the MFA collection, damage can be observed where wood was infiltrated by adjacent water-bearing plaster fills or other restoration. These plaster fills often obscured original surfaces and altered the color and saturation of polychromed areas. They were also often heavier and stronger than original materials and were intractable and difficult to remove. In addition, treatment with alkaline fill materials such as plaster could accelerate damage in associated areas of wood within a very short period of time (Blanchette et al. 1994). For this reason, filling materials that do not contain calcium carbonate or sulfate or involve water have been favored, such as glass microballoons in acrylic resins.

Polychromed wood in the MFA collection, which had been treated with cellulose nitrate, animal glue, and PVAC emulsions, show contracted, curled, and flaking paint surfaces. Even in the case of wax, where flakes might be immobilized, they remained fragile because they were separated from the substrates. Although more recently the use of water-based consolidants such as gelatin provided the possibility to soften and re-adhere polychromy to gesso and gesso to wood, they often resulted in staining and tended to dissolve the poorly bound paint and gesso layers before they could be re-adhered. Over the past 15 years, the use of cellulose ethers such as Klucel G as preconsolidants in conjunction with methyl cellulose provided improvements in re-adhering polychromy to substrates without damage or discoloration and maintained the possibility of later re-treatment should it become necessary. Hand-colored tissue papers are regularly used in conjunction with cellulose ethers for visual integration of polychromed surfaces (Hatchfield 1988). Plaster-based fill materials have also been largely replaced with glass microballoons in acrylic resins such as Paraloid B-72, creating lightweight, easily reversible fills for fragile and sensitive objects (fig. 18) (Hatchfield 1986). Paper pulp–based fills have been used as well (Podany et al. 1995).

Among the most important of the wood artifacts are the coffins of Djehutynakht (called the Bersha coffins) (MFA 20.1822) and tomb models from the tomb of Djehutynakht. Although problems with treatment in the field were noted immediately after excavation (see Part 1, G�nsicke et al. 2003), no treatment record for the Bersha coffins were found between their arrival at the MFA and 1984. However, the coffin panels were installed in sealed cases incorporating silica gel, probably in the 1960s. The lid did not appear to have been treated, but the east panel had been treated with hide glue and an ethanol-soluble resin, PVAC. The ends had been consolidated with a milky white adhesive (PVAC emulsion?). Calcium oxalate was identified on the surface of the coffin, presumably having formed in the tomb. In 1984 areas of raised cleavage were softened

Fig. 18.

A microballoon-acrylic resin fill material is used to substitute for the severely deteriorated wood interior of the shawabti of Huy. Provenance unknown, New Kingdom, 19th–20th Dynasties, 1293–1070 B.C., polychromed wood, height 23.5 cm. MFA 72.4902, Hay Collection, Gift of C. Granville Way, 1872. Courtesy of Pamela Hatchfield, 1986

Since the mid-1980s, many of the tomb models have been treated with cellulose ethers and tissue paper fills for exhibitions, loans, and gallery installations. In the summers of 1992 and 2000, Nadia Lokma, head conservator at the Egyptian Museum in Cairo, matched missing parts and conducted stabilization treatments of the polychromed models from the tomb of Djehutynakht using methods based on those now applied to similar artifacts at the MFA. Treatments utilized cellulose ethers; Paraloid resins and microballoons; and Plexisol B 597 5% in toluene and trichloroethane. During reconstructions following excavation, component parts of the tomb models were sometimes mismatched, resulting in inaccurate representations that lasted for many years. This was the case with the Bersha Procession, which was reconstructed in 1941 and again in 1987, in preparation for the exhibition Mummies and Magic (D'Auria et al. 1988). This reconstruction, which utilized some newly identified fragments found in storage, produced a new and more accurate reconstruction. Attributes such as the mirror case were definitively placed based on the presence of remains of original cordage and other evidence, and other fragmentary elements (such as a table) were identified, correctly located, and restored with balsa wood.

The Henettawy coffin treated with wax in the field had undergone some reconstruction with hide glue while at the Metropolitan Museum of Art in 1925. At some point, the coffin had also been heavily consolidated with cellulose nitrate, although no records have been found describing this treatment. Leaking steam pipes in storage caused further damage during the late 1970s or early 1980s, although the damage was less than it might have been had the artifacts not been previously consolidated. Nevertheless, the coffin required treatment in 1987 and again in 1998. Paraloid B-72 in toluene was applied to facilitate manipulation of the wax and cellulose nitrate–saturated gesso and polychromy. In this instance, as with many objects that have undergone previous treatments, methods and materials are chosen more for their interactions with previous treatment materials than with the original materials of fabrication.