Deterioration of Some Archaeological Materials

Hydrogen Sulfide. Hydrogen sulfide is a foul-smelling gas that is released into the atmosphere from volcanoes as well as in the course of decay of animal tissues. As an air pollutant, it reacts with almost all metals, with the exception of gold, forming a dark-colored corrosive layer of metal sulfide, commonly known as tarnish, which discolors the exposed surface of most metals. 

When salts in groundwater precipitate and crystallize within the cavities of buried materials such as pottery, cement, and wood, they may generate internal pressures sufficient to disrupt these materials and turn them into gravel. Salts are also active in blistering and scaling painted surfaces on a variety of materials. 

Well-fired pottery, fired at temperatures above 850°C, is a very stable material in fact, it is practically inert and indestructible. If the firing temperature is low, however, say below 600°C, an inferior material is obtained that rain 

Skin is unstable to varying environmental conditions and deteriorates readily under humid conditions or through biological activity, or both. Basically, the decay of much ancient skin and hide results from hydrolysis, that is, the reaction of the protein fibers in the skin with water in extreme cases, the hydrolysis of skin and hide may cause their total dissolution, and quite often, under humid and hot environmental conditions, nothing remains to indicate that skin or hide was once there. 

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Some dry archaeological wood may be riddled by insect activity and require consolidation. Hillman and Florian (24) have described a sandwich type of deterioration of boards of a bentwood box. The boards are virtually a sandwich of paper-thin outer surfaces between which the wood is completely riddled with lyctid beetle galleries and tunnels filled with frass. This porous material is easily, consolidated. 

Surely a few thought about the material, the wood, now archaeological wood about the physical and chemical state of the wood and the task of conserving this waterlogged wood about how the unique burial environment, through some fluke, allowed this wood to evade the natural cycle of deterioration for 333 years and about the secrets hidden in the wood, such as information about its age and the environment in which it lived, secrets revealed in its unique growth patterns. 

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