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  for Metal Finishing since 1989
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Treatment of tin pest in Chinese antiquities

I examine Chinese antiquities, and occasionally encounter tin-plated bronze. I hope that my questions concerning tin pest are not inappropriate for this site, as they concern the handling of artifacts, rather than the prevention of the disease through alloying, etc. I have never encountered an artifact with tin pest, but the conservator in me is still curious. I have been unable to find any information on stabilizing tin pest, once it has developed. Several sources have given the impression that elevating the temperature above the critical 13.2 °C is ineffective, and can actually exacerbate the situation. Another source mentioned that certain solvents accelerate the deterioration, but failed to mention the solvents, or to give a reference list for further study. Can you point me in the direction of data on either problem?

Melanie Roy
asian antiquities (director of research/archaeomaterials studies) - Williamsburg, Virginia, USA
2005

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First of two simultaneous responses --

I can't quite answer you question directly, but...if tin pest is going to appear, it will do so quite soon, i.e., it won't appear later on antiquities. Over time, say a few years, the copper in bronze will have alloyed considerably with any tin coating, and this will prevent tin pest too.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005

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Second of two simultaneous responses --

Tin pest is caused when the tin changes from a tetragonal to cubic structure. This happens (in pure tin) at 13.2C, but the presence of any other metal will inhibit this transformation to a much lower temperature. I believe the tunic buttons on Napoleon's army coats suffered from tinpest when they invaded Russia and they all fell to pieces. However, I have never actually seen this happen. I also believe that once it starts it is very difficult to start and to be honest, I do not know how it can be. I would suggest you ask other conservationists, as they will probably have greater experience in this quite specialised subject.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2005

Try Conservation OnLine website(http://palimpsest.stanford.edu/)!

Goran Budija
- Cerovski vrh Croatia
2005