Data on Rust Oxidation and the Effects of Corrosion.

When iron is conserved by electrolysis, it depends upon the oxidation state of the iron corrosion products as to whether or not they can be reduced. If the corrosion products are in a ferric state the most one can expect is mechanical cleaning of the corrosion layers by the evolution of hydrogen gas bubbles. If the iron corrosion products are in a ferrous state, it is often possible to convert them to magnetite, and possible some to metal, which preserves the original surface details contained in the corrosion layers.

During the reduction process, the chlorides are removed from the artifact. Electrolytic reduction is one of the most valuable and misunderstood tools of the science of conservation. Although used extensively by conservators treating artifacts from marine sites, many conservators consider it only a mechanical cleaning treatment.

Following any conservation treatment through a rust remover, it is usually necessary to make the conserved metal surface more corrosion resistant and to seal the surfaces off from the atmosphere. Iron is often treated with several cots of dilute tannic rust removal acid to color the iron black and the ferric tannate that is formed makes the iron more resistant to corrosion. A sealant of microcrystalline wax or various paints is applied as a final step. Soaking copper alloys in 1 to 2 percent benzotriazole following treatment lessens the tendency of the metal to corrode and a final sealant of wax or resin completes the conservation from rust oxidation.