9 ORGANIC MATERIALS

9.1 TYPES OF MATERIALS AND NUMBER OF OBJECTS

Objects and substances of organic nature provide a particular wealth of botanical and faunal information, the importance of which Reisner understood early on. Due to the mostly utilitarian or decorative uses of these materials, viewed secondary to fine art, much remains unpublished, unaccessioned, and unknown to date. Of approximately 1,000 accessioned objects, more than 700 consist of bone and ivory.

Natural fibers were used for the production of baskets and funerary sandals and for coil, string, and cordage. Burial goods also include food offerings, grains, and flowers. Animal materials such as leather, hide, and gut can be found on clothes, scabbards, and as tying materials, while human and animal hair was essential for the production of wigs. Leather objects from Kerma occasionally contain applied decorations of faience or metal. Woven fur strips appear on a seat cover from Kerma, and ostrich feathers were worked into fans. Bone and ivory supplied carving material for small amulets, bangles, inlays, game pieces, seals, sculptures, furniture inlays, and other decorative items. Also used for beads and jewelry were ostrich egg, shells, mother of pearl, and amber. Tortoise shell and horn were shaped into knife handles, combs, and inlays. Natural wax has survived in the form of small figures or as a paint medium on later mummy portraits.

Mummified human and animal remains and preserved body parts and organs are integral to Egyptian funerary culture and, thus, to excavations of necropolises. Most of the osteological material found by the Harvard University–MFA Expedition is now housed at the Peabody Museum of Archaeology and Ethnology at Harvard University, while human and animal mummies remain at the MFA.

Often, residues of oils, fats, and resins can be found in stone and ceramic vessels, intentionally applied as varnishes on polychromed wood or as embalming or libation materials on coffins and mummy wrappings. Composite organic substances constitute cartonnages, built from layered linens, soaked with gum, and shaped as coffins, mummy trappings, or containers, which were often finished with gesso and painted. Textiles and papyrus, a sizable part of the collection, are treated by other disciplines.

9.2 TREATMENTS IN THE FIELD

Most of the methods discussed here were found in the early conservation literature and are evident on objects in the collection. Much was written about ivory and bone, but other materials are covered less thoroughly. While Petrie and Lucas were intimately familiar with Egypt, much of Rathgen's work was also concerned with finds from northern European archaeological contexts.

9.2.1 Bone and Ivory

Lucas (1932) mentioned the washing of bones with soap and warm water, but cautioned that, overall, water should be used sparingly and better warm than cold. He stated that ivory in good condition could be cleaned with damp sponges or brushes; in poor condition it should not be wetted, and soaking should be avoided since it could lead to splitting. Petroleum spirit could be substituted for water on fragile surfaces (Lucas 1932).

The impregnation with wax, applied in melted condition by immersion or gradually by brush and pipette, was advocated by Lucas (1932) as an ideal treatment method for many types of materials in the field. He elaborated on the importance of choosing an appropriately high melting type to avoid its melting on objects in the summer. Paraffin wax was used for bone, horn, ivory, plaster, and wood (Lucas 1932). He was also aware that paraffin could pose significant difficulties to subsequent laboratory treatment, since it was almost impossible to remove, and therefore he asked for alternative methods if extensive future work was anticipated. Ivories in Nineveh were boiled in gelatin, which Lucas thought would be disastrous on Egyptian pieces; he also mentioned the use of glue by Wolley at Ur (Lucas 1932). Lucas advocated strengthening of ivory with a 1% solution of celluloid.

Petrie (1904) discussed ivory that can be flaking, particularly in wet soil, and advised that it be block-lifted and dried slowly before brushing off soil. He also was in favor of paraffin wax and suggested that darkening, caused by wax, could be removed with a poultice of heated fuller's earth. Of all the organics other than wood, he seemed to focus only on ivory and bone.

Rathgen (1905), on the other hand, preferred isinglass, or glue since aqueous solutions could be used on damp material. He recommended the use of dilute solutions at high temperature of approximately 120�F, perhaps in combination with a bell glass. Fragile pieces should be bound with strips of gauze, and the addition of corrosive sublimate to the glue would prevent mold growth (Rathgen 1905). After such an impregnation he advocated coating with shellac or resin.

Petrie (1904) observed crystalline carbonate accretions on ivory, which were harder than the original substrate. After consolidating the ivory in wax and wiping off its excess with benzol or ether, he recommended the use of nitric acid to dissolve the crystalline lime: “Even strong nitric acid will only dull the surface of waxed ivory, and not remove any perceptible amount, while it dissolves the concretion rapidly” (Petrie 1904, 92).

Lucas (1932) also addressed the problem of accretions, but in a more careful manner recommended dilute acid (5 parts hydrochloric acid, 95 parts water), which would be brushed repeatedly and needed to be washed out until test results were neutral.

Petrie's (1904) recommendations for desalination of wood, discussed above, could also be applied to bone or ivory.

One of the MFA excavation publications states that bone can be “treated with a solution of shellac in spirit before being measured or the skull repaired, as they were in fragile condition” (Dunham and Simpson 1974, 21). Lucas cited Kish's method of “melted wax poured over the bones until they were carefully encased in a damp proof solid envelope” (Lucas 1932, 75–76).

9.2.2 Leather

Rathgen (1905) preferred the Copenhagen method, which rendered leather soft by placing it in train oil for an hour and then drying it with filter paper. He recommended lanolin as well as poppyseed oil in benzene.

Lucas (1932) observed that leather was subject to deterioration and became brittle when dried. In heat, it could turn almost viscous, and it would blacken upon drying and take on the appearance of resin. He warned that exposure to sunlight and sulfuric acid could be damaging, particularly on certain vegetabletanned leather. Well-preserved leather could be cleaned with soap and water, as neutral as possible. According to him, the leather should then be brushed while still damp with a rag, and castor oil could be used to restore its suppleness. He also cautioned against the use of oils that turned acidic (animal, vegetable, neat's-foot, and olive oil) and recommended castor, lanolin, sperm oil, and Vaseline, sometimes used warm. Oil and grease darken leather, however, and dyed or light-colored leather could easily be spoiled. He noted that if leather had become too brittle, a mixture of 75% alcohol and 25% castor oil was useful. Cockroaches, silverfish, and beetles were recognized as dangerous, and methods to control them will be discussed below (Lucas 1932).

9.2.3 Fabrics and Hair

Rathgen (1905) stated that other than removal of earth and soil, not much was needed for fabrics and hair. After drying, impregnation with a gum-damar solution, poppy-seed oil, or a solution of India rubber seemed desirable.

9.2.4 Feathers

Rathgen (1905) recommended immersion in alcoholic solutions of corrosive sublimate or spraying with corrosive sublimate in alcohol or aqueous solution, which he realized was poisonous. He mentioned that naphthalene was not always useful; neither was finely powdered pepper, when mixed with alum. Lucas (1932) recommended strengthening brittle feathers by spraying them with a very dilute solution of celluloid (approximately 0.5%).

9.2.5 Horn

According to Lucas (1932), horn did not need more than cleaning with lukewarm water, but he warned against insect attack.

9.2.6 Basketry

Basketry became desiccated and brittle, but remained fairly stable in the Egyptian environment, requiring surface cleaning. Saturation with melted paraffin wax was the only recommendation Lucas (1932) had for severe cases. He saw the darkening effect of the wax as desirable.

9.2.7 Resins and Wax

The extent to which true amber (fossilized resin) was available in ancient Egypt is unknown, but in the past, various artifacts that may have been made from lumps of modern resins may have been misidentified as ambers, and treatments considered appropriate to amber may have been applied to these. Lucas (1932) thought that fossil resins, since they were buried for geological times before being used by man, would not be adversely affected by burial and could be washed with soap and water. Rathgen (1905) suggested mechanical cleaning by rubbing between fingers covered with a woolen glove and by impregnation with shellac, poppy-seed oil, and isinglass. He also mentioned the preservation of amber in distilled water to which were added small amounts of glycerin and alcohol; greater than 1% of the latter would be injurious to the amber.

Other resins, according to Lucas (1932), were often brittle and too tender to bear any treatment other than washing in warm water or brushing. He suggested that repairs could be carried out with celluloid cement. He cautioned against the use of alcohol and other solvents on resinous varnishes, but he removed deposits of organic nature (grease, oil, resin, and tar) with organic solvents.

Lucas (1932) wrote that ancient beeswax was cleaned with soap and water, as well as alcohol, and that it was treated by chloroform applied with brushes.