In addition to active treatment of finds, a major part of our work is preventive conservation, including maintenance of proper storage conditions to reduce future degradation. One annual task is renewing the bags of silica gel at the artifact storage depot. Silica gel is used as a dessicant, just like in those little packets that come with new shoes. (Silica gel can also be “conditioned” and used as a buffer to maintain a certain humidity).
|Silica gel beads|
Bags of silica gel are placed with groups of copper alloy artifacts in archival boxes. Like many degradation reactions, bronze disease, a nasty form of copper corrosion caused by the presence of chlorides, is moisture dependent. Left untreated, “infected” objects will disintegrate to green powder. The silica gel maintains a dry environment inside the box, preventing further copper corrosion. As mentioned in an earlier post, copper alloy objects at Gordion are routinely treated with BTA, a corrosion inhibitor, but a dry environment provides another layer of protection.
|Unfortunately not for making pide (Turkish pizza)|
Here’s the finished result: the indicator strip placed in the box with the renewed silica gel shows there’s no moisture and that the copper alloy objects are safe for another year.
|A dry storage container|