In 1804, seven men escaped from a New Hampshire (US) prison. A pewter key to the prison door was dropped on their way to a nearby bridge.
Question: Was it ordinary to make a key intended for practical use from a metal as soft as pewter?
The only example I could find of a pewter key was in a story of British prisoners attempting to escape from an American prison in 1799 using a key they made from a spoon. (The key broke inside the lock.)
I'm trying to determine if the 1804 key was likely to be one the jailer might have used, or an unauthorized duplicate someone made.
Sounds like an unauthorized duplicate. Though the antimony content makes pewter harder than only lead and tin ( the other typical components of the alloy), it's still pretty malleable, which is why it would be used for spinning- a sheet of it could be spun on lathe and shaped into platters and plates and cups in somewhat the same way a potter can shape a clay bowl on a wheel. It would be hard to use it as a permanent key, therefore: even in a simpler warding lock (which is what you'd expect in 1800) where the keys could be relatively simple and kind of massive- the classic "skeleton keys". So it's a pretty safe bet that because pewter melts at a low temperature, the basic key was cast in a simple mold and then altered to fit the lock- turning it would tend to leave the marks of the wards, so it could have been filled or perhaps even whittled until it worked. And, of course, it would only have had to work once, in order to turn them loose..