Pseudomorphs

The conservation team often has to carefully examine metal artifacts for pseudomorphs before cleaning.

Pseudomorphs are casts of organic materials in the metal corrosion products and can provide insight on types of materials that may not be preserved otherwise. They form when organic materials are buried in contact with a metal surface. Both positive casts and negative casts can be found, depending on whether the metal cations penetrated and replaced the organic material or if the corrosion products were deposited on the surface leaving an imprint of its structure.1

This is an example of the preservation of a piece of wood on the surface of an iron object.

Textiles can also be preserved. This image shows the remains of a textile preserved on a copper alloy ring. The twists of the threads of the textile can still be seen.


This pseudomorph of wood found on a copper alloy knife shows how much detailed information of the structure of the organic material can be preserved.

1. Carroll, Scott A. 1997. New Thoughts on the Preservation of Bronzes. Anatolian Archaeological Studies VI (6):301-307.

Scott, DA. 2002. Copper and Bronze in Art: Corrosion, Colorants, Conservation. Los Angeles: Getty Conservation Institute.