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'''Tin pest''' is an [[autocatalysis|autocatalytic]], [[Allotropy|allotropic]] transformation of the element [[tin]], which causes deterioration of tin objects at low temperatures. Tin pest has also been called ''tin disease'', or ''tin leprosy'' (''Lèpre d'étain'').

It was observed in [[medieval]] [[Europe]] that the [[organ pipe|pipe]]s of [[church]] [[pipe organ]]s were affected in cool climates. As soon as the tin began decomposing, the process sped up, and seemed to feed on itself.

==The allotropic transformation==

At 13.2 degrees [[Celsius]] (about 56 degrees [[Fahrenheit]]) and below, pure tin transforms from the (silvery, ductile)  [[allotropy|allotrope]] of β-modification ''white tin'' to brittle, α-modification ''grey tin''. Eventually it decomposes into powder, hence the name ''tin pest''.

The decomposition will [[catalyst|catalyze]] itself, which is why the reaction seems to speed up once it starts; the mere presence of tin pest leads to ''more'' tin pest. Tin objects at low [[temperature]]s will simply disintegrate.

==Possible historical examples==
===Scott expedition to Antarctica===

In [[1910]] British polar [[List of explorers|explorer]] [[Robert Falcon Scott|Robert Scott]] hoped to be the first to reach the [[South Pole]], but was beaten by [[Norway|Norwegian]] explorer [[Roald Amundsen]]. On foot, the expedition trudged through the frozen [[desert]]s of the [[Antarctic]], making for caches of [[food]] and [[kerosene]] deposited on the way in. In early [[1912]], at the first cache, there was no kerosene; the cans &mdash; [[solder]]ed with tin &mdash; were empty. Members of the expedition later died in the cold and [[blizzard]]s, only eleven miles from a massive depot of supplies.

The cause of the empty tins is unknown. Some observers blame poor quality soldering, although tin cans over eighty years old have been discovered in Antarctic buildings with the soldering in good condition. In any case, the lack of kerosene was just one factor in the deaths. One source observes,

<blockquote>The likely cause of death for Scott's polar party was some combination of scurvy, gangrene, starvation, dehydration, and hypothermia.<ref>[http://www.wilderness.net/library/documents/glover.pdf On Robert Scott's mission to the South Pole]</ref></blockquote>

===Napoleon's buttons===

The story is often told of [[Napoleon]]'s men freezing in the bitter Russian winter, their clothes falling apart as tin pest ate the buttons. Whether failing buttons were indeed a contributing factor in the failure of [[Napoleon's invasion of Russia|the invasion]] remains disputed; critics of the theory point out that the tin used would have been quite impure and thus more tolerant of cold temperatures. Laboratory tests provide evidence that the time required for unalloyed tin to develop significant tin pest damage at lowered temperatures is about 18 months, which is more than twice the length of Napoleon's Russian campaign.[http://www.straightdope.com/columns/080509.html]

==Modern tin==

Today tin casting and plating avoids tin pest. The tin is [[alloy|alloyed]] with small amounts of [[antimony]] or [[bismuth]], which prevent the decomposition. [[Silver]], [[indium]], and [[lead]] have also been used.

==References==
<references/>


[[Category:Metallurgy]]
[[Category:Tin]]
[[Category:Allotropy]]

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