NCS Conservation of Pewter Coins

Ed62

Does anyone have any experience/ good advice about the effects of NCS 'conservation' of a pewter coin; i. e. a Continental Dollar? NCS says they can do it, but has anyone ever seen a 'conserved' pewter/tin coin?

I have a fairly nice Continental Dollar with some unattractive darker toning spots on the Rev. If it were silver it would definitely benefit from some conservation work. But pewter?? The chemistry of pewter reactions with dipping agents must be different than gold/silver/bronze. Will there be longer term negative effects?

dthigpen

I'd have to agree that a Lead/Tin mix is not something I'd want to try and 'clean up'.

XpipedreamR

I think you can probably scrub those spots off with the corner of a little Brillo pad...




Added: not!

Pistareen

Hi Ed:

The spots on your Continental dollar are part of the coin, rather than something that sits on top of it (like encrustation or rusty toning on a sea-salvaged gold coin). For this reason, I wouldn't foresee success on trying to "curate" it.

The pewter in your Continental dollar is actually an alloy called "Ley's metal" : more than 3/4 made of tin, nearly 1/4 lead, with about 1% each copper and silver, and some trace elements. Those spots (if they're raised, dark, and a little rough) are a by-product of those elements doing exactly what they're supposed to in Earth's climate, which is why they're so commonly seen on Continental dollars and other coins that are mostly tin (American Plantation tokens, some halfpennies from late 17th century Britain, etc.) They happen on all sorts of Continental dollars from well worn to otherwie gem.

I've catalogued or otherwise handled at least a few dozen Continental dollars, mostly in the EF to Unc range, and more often than not they've had those spots. I don't think I'd worry about them on yours, as they come with the territory and probably can't be changed.

Congrats on owning a Continental dollar! It's one of my all-time favorites -- now you just need the paper Continental half, third, quarter, and eighth dollars (issued February, 1776) to complete your set!