Did Tin Pest Cause Napoleon to Experience a Wardrobe Malfunction??

The story of Napoleon’s buttons is one of those great cautionary tales about the potentially dire consequences of ignoring the chemical properties of substances.

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Most engineering students probably first heard about this historical wardrobe malfunction (apologies to Janet!) in an introductory chemistry class:

As the story goes, the tin buttons on the coats of Napoleon’s troops literally crumbled to a powder after being exposed to the bone-chilling cold of a Russian winter. The culprit? A metastable material, pure tin undergoes a structural transformation at low temperatures (below 0C), essentially decomposing into dust.

This transformation is called tin pest, which can be avoided by combining tin with other elements, like, you know, lead.

Given the much debated issue over the reliability of new lead-free solders dictated by RoHS regulations that went into effect last year, the button story is making its rounds again in engineering circles, including here in this blog. And that of course got me wondering whether there is any shred of truth to the tale.

“It’s a story that virtually every chemistry student has heard, but we don’t really know if Napoleon’s army actually had buttons made of tin,” says Penny LeCouteur. She’s co-author of the book “Napoleon’s Buttons” How 17 Molecules Changed History,” a highly entertaining look at chemical compounds and their impact on the course of history.

It’s a ripping good read:

There are many stories that engineers will remember or can relate to, like the O-ring failure on the NASA space shuttle with just enough science to be credible without feeling the need to run for your CRC Handbook of Chemistry and Physics.

Though the section on Napoleon’s wardrobe is a mere couple of pages, LeCouteur, a former chemistry professor and now administrator at Capilano College, says that while she was researching the book she was struck by photos of old tin vessels that are now in museums. “What amazed me was that they no longer had that sharp outline to their geometries, which made sense because these objects were exposed to the frigid winters in northern Europe. Victims of tin pest, the outer layers simply turned to powder and sloughed off. “ Theoretically, Lecouteur says that the same thing could have happened to Napoeleon’s buttons. But she says that there is simply not enough evidence to conclude that it did.

“There were eyewitness accounts and you do see paintings that were made of Napoleon and his troops at that time holding old carpets and blankets around themselves to keep warm, so we do know about the kind of cold they had to endure. But buttons made out of pure tin would have been quite expensive compared to wood or bone. And chemically, tin pest is a very slow process.”

In fact, LeCouteur says that a colleague stuck a pot of tin in his fridge as an experiment. “After several months, he couldn’t detect any difference in the sample. So it’s likely Napoleon’s troops would have had to endure some hellishly long winters before their buttons distintegrated.”


Comments

4 comments

  1. Personally, I do not believe the Napoleon’s buttons story. But it got me interested in
    tin pest (tin plague, tin leprosy, tin disease, tin blight), and since late 2004 I have
    collected 89 books/theses and 215 papers/reports/magazine articles on this subject– see
    http://www.dbicorporation.com/tinpest.htm.
    For books and theses I list the specific pages with information on grey/gray tin, or
    on the allotropic transformation between beta-tin (white tin) and alpha-tin (grey tin).
    I recently found an English translation of Aristotle’s book

    de Mirabilibus Auscultationibus
    , written about 350 B.C. Ernst Cohen, a
    Dutch scientist who wrote over 40 papers on tin pest from 1899 to 1939, interpreted item 50
    (on page 834) as referring to the volume expansion of tin pest.
    The next reference that I’ve found to tin pest was an 1851 paper by O. L. Erdmann, on
    the disintegration of tin pipe-organ pipes in very cold weather. Since about 1897 there
    has been a slow, but continuous, stream of publications about tin pest, with a huge
    increase since 2004 (when people started becoming really scared about the side effects
    of the RoHS Directive).
    In 2007 the National Physical Laboratory (NPL) made a time-lapse movie showing beta-tin
    changing to alpha-tin. The researchers, D. Di Maio and C. Hunt, have written a paper,
    “Time-lapse photography of the beta-Sn/alpha-Sn allotropic transformation”, which shows
    some clips from this movie. This paper is scheduled to be published in the Journal of
    Materials Science: Materials in Electronics.
    To date I’ve collected over 13,400+ books, theses, papers, reports, magazine articles,
    web pages, etc. on lead-free electronics, the RoHS and WEEE Directives, and their ilk– see
    my 3.4MB, 900+ page bibliography at
    http://www.dbicorporation.com/rohsbib.htm
    My original intent was to write a web page to supplement my books Robust Electronic
    Design Reference Book, Volumes I and II, which I wrote in 2003. But I’m still researching
    the engineering and scientific literature, and my confidence in the quality/reliability/
    longevity of new electronics keeps on dropping! With my stash of 70+ pounds of tin-lead
    solder, I figure that I should be able to keep my pre-2006 electronics working for a
    long, long time, but I don’t know about the rest of you…
    John Barnes KS4GL, PE, NCE, NCT, ESDC Eng, ESDC Tech, PSE, SM IEEE
    dBi Corporation
    Lexington, KY

  2. The story I’d heard was that Scott (of the Antarctic) suffered from a lack of fuel because the tin cans holding the paraffin (kerosene) for the stoves suffered the tin pest then rusted through. These storage dumps would obviously be there for a long time in the cold. The residual water within the paraffin would still be held a liquid and support the rusting.
    The same could have happen to Napoleon’s buttons.

  3. Thanks for the extra research on tin pest. At temperatures of -50C or more, when the transformation is quickest as you state, Napoleon would certainly have had to worry about more important things than buttons falling off!

  4. Reaching for my copy of Partington’s General and Inorganic Chem. to visit something last looked 40 years ago…….!
    White tin starts the transition to the grey form at 13.2 deg. C. The transformation happens fastest at -50 deg.C. So it is true that the effect accelerates as the temperature drops.
    I also note that the grey form has the same crystal structure as diamond.

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