Jubiläumsfonds der Oesterreichischen Nationalbank Project No. 11990Analysis of corrosion phenomena and optimisation of the storage conditions for antique bronze coins showing a high lead content
DI Dr. Martina GRIESSER Co-workers:
René TRAUM (Coin Cabinet), HR Dr. Günther DEMBSKI (Coin Cabinet), Dr. Klaus VONDROVEC (Coin Cabinet) For antique Greek and Roman bronze coins kept in the collection of the Coin Cabinet showing a high lead and/or tin content the formation of a white, powdery corrosion can often be detected. Even coins appearing to be in good condition by only visual inspection can in fact already be severly corroded inside. In these cases often only a thin mantle of metal or patina is present that can collapse nearly anytime. To preserve the numismatically and historically important and unique pieces this project investigates the composition of the coins and of the corrosion products by applying a variety of modern analytical methods. The goal is to identify the coins most endangered by advanced corrosion. These coins together with the ones endangered by corrosion due to the still on-going storage within (oak) wooden cabinets will be moved to a new optimised storage case made from metal. In co-operation with the manufacturers this metal case will be adapted for the purposes of storing sensitive coins by e.g. including nitrogen flooding or special air filtration systems.