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Changes in tin pest

 

Sometimes extreme physical changes result in permanent changes in tin pest. What causes this physical change?

Dmitriy Kalan
- Teaneck, New Jersey

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Extreme cold. See letter number 0740 .

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Pure tin can exist in two allotropic forms white tin (beta) and grey tin (alpha), low temperatures can result in re-crystallisation of the white from to the grey from, in practice for the change into the grey form the tin has to be of a high purity (transformation is retarded by soluble impurities) and exposed to temps well below zero.

There is a story of one of the Russian Tsars keeping a cellar full of tin the gist of it being that after a particularly hard winter it had turned to dust !. How true this is I've no idea could be an urban myth from 200 years ago.

On the other hand Tin food can from the Scott expedition to the antarctic in 1911 were recovered and examined by the Tin Research Institute in 1957 with no trace of grey tin found in the tin coating.

An interesting article is Tin in Cold Service By R.M MacIntosh (Tin Research Institute Inc USA).

Regards,

Richard Guise
- Lowestoft, U.K.