TSG Chapter III. Environmental Concerns for Textiles - Section E. Archaeological Environment

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Archaeological Environment

Introduction

Textiles have been used by humans in many ways. They are used to create clothing, shelter, or as tools to accomplish a task. Generally, textiles are made of fibers that are joined in some way. A fiber can be commercially defined as a long, narrow, and flexible material that may be of animal, plant, synthetic, or mineral origin or zoologically as an external, multicellular structure made up primarily of protein (Robson and Ekarius 2011). Cellulosic fibers come from plants and proteinaceous fibers from animals. Cellulosic fibers are composed of cellulose, and include hair cells, like cotton, and bast fibers, like linen. Proteinaceous fibers are composed of keratin, including wool, hair, and kemp fibers. Wool tends to be the finest fiber in a fleece, and is characterized by crimp and elasticity. Hair fibers are straight, smooth, and inelastic, and are stronger than wool fibers. Kemp is the heaviest and coarsest of the fibers in a fleece (Robson and Ekarius 2011). Silk, another protein fiber, is composed of fibroin, and is made from the unwound cocoons of silk worms (Cronyn 1990). Synthetic and mineral fibers, such as rayon or fiberglass, have only entered the archaeological record in the last century, and possess their own issues in waterlogged environments. Individual fibers are spun together, adding length and strength. These linked fibers are then woven, looped, or matted together to create fabric. Common methods of joining fibers include weaving, knitting, basketry, rope making, and felting. These fabrics and spun fibers can be altered through dyes or the addition of metallic threads or gold leaf (Cronyn 1990). This being said, the presence of textiles in the archaeological environment is uncommon, especially in wet and waterlogged contexts.

Condition

In some cases, textiles from wet or waterlogged environments appear to be in good condition. However, there are a variety of factors that influence the condition of archaeological textiles. Deterioration within a textile may not be uniform, with sections that were more exposed during the objects use-life or burial period exhibiting more damage than other areas (Peacock 2005). Fibers within the textile may be affected by hydrolysis. As a result, individual fibers may be broken, weakening the entire textile (Cronyn 1990). Pressure from the deposits above the textile may deform the fibers, and the action of microorganisms and plants may damage or totally destroy the artifact (Peacock 2005). This weakening and fragmentation of fibers through hydrolysis may make one material look like another; longer animal fibers may appear to be a plant-based fiber. This weakened fabric may be fragmented within the archaeological deposit, making identification of the original artifact more difficult. It is also possible that this weakness may not be apparent until the artifact is taken back to the lab and cleaned. In that case, the textile may require some form of support to prevent fragmentation during and after treatment. Because the condition of textiles can be hard to determine without additional tools, block lifts are recommended to limit damage to the textile (Cronyn 1990). In addition to alterations in the characteristics of the fibers, additions to the fibers may change during burial. In the case of dyed fabrics, the dyes may leach out into the surrounding environment (Cronyn 1990). Certain dyes are more likely to leach than others, based on the components of the dye. Dyes can also act as biocides, preventing decay, or can speed deterioration, depending on its composition. Color changes due to the environment are also possible. Tannins in the soil can darken light fabrics, and metal corrosion products can also discolor textiles (Cronyn 1990). Copper corrosion products may add greenish colors to a textile, and iron will cause a range of orange to rust brown staining. Textiles, as very fragile articles of material culture, also may undergo additional deterioration after excavation. Due to the weight of water, weakened textiles may tear, especially if the textile was folded and is subsequently unfolded in air. Weakened fibers will be somewhat supported when textiles are unfolded underwater, decreasing the likelihood of fragmentations. Abrasive substances, such as silt or sand, may be carried into a textile during burial. As the textile is moved or cleaned, these internal abrasives can cause damage to the fibers. This damage varies in its overall effects. Some textiles will not become visibly damaged, while others will fragment. Wet organics are also at risk for attack by mold, bacteria, and fungi as well. These organisms can stain or completely destroy a textile. Finally, waterlogged textiles are at risk during the drying process. In the case of both plant and animal fibers, water provides internal support for individual fibers. If the internal structure, such as cellulose in plants or keratin in animals is damaged by hydrolysis, water may be the only support for the fiber. As the textile dries, loss of support can lead to the collapse of the fibers, altering the structure of the textile (Cronyn 1990).

References

Cronyn, J. M. 1990. Elements of Archaeological Conservation. New York, New York: Routledge.

Peacock, E. 2005. Investigation of Conservation Methods for a Textile Recovered from the American Civil War Submarine H.L. Hunley (1864). In: Proceedings of the 9th Wet Organic Archaeological Materials Conference, Copenhagen, pp. 497-512.

Robson, D. and C. Ekarius. 2011. The Fleece and Fiber Sourcebook. North Adams: Storey Publishing.

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