What is a corrosion inhibitor?
Typically a corrosion inhibitor is a chemical that reacts with the surface of a metal to create a protective coating. This coating is unlike the one formed by a plastic or wax, as it is formed by a chemical reaction between the inhibitor and the metal ions at the surface of the object. In other words the protective coating becomes part of the surface of the object. Two corrosion inhibitors used commonly in archaeological conservation are benzotriazole (BTA) and tannic acid. Benzotriazole (BTA) has proven to be very successful for stabilizing copper alloys. Although BTA has been in use since the 1960’s, research is ongoing to find out exactly how this inhibitor actually works. The one disadvantage of using BTA is that it is a suspected carcinogen, so safety precautions should be taken when treating the object and handling it after treatment. BTA is also useful for stabilizing silver objects that have been alloyed with copper. Tannic acid is used to inhibit iron corrosion. Brushed onto t
