Re: About those addititeis in shrinking...
Posted by Bert Hickman on 2/2/2009, 11:42 pm, in reply to "About those addititeis in shrinking..."
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: Just wondering if the ripples puffs and other oddities whihc happen with
: coins are a result of the stresses incorporated into the coin by the
: manufacturing process...
: If so, heat treating them might reduce or at least introduce something
That's a good idea... but I don't think it will have much effect.
Shrinking coins is a very delicate balancing act. We're trying to balance incredibly large forces so that they are symmetrically distributed across the entire coin. We've found that slight force imbalances, due to differences between the surface patterns stamped on the on the head and tail sides of the coin, and where the cladding sometimes has areas of slightly weaker bonding, combine to create slight wrinkling and waviness. The wrinkling, projections and matching hollows (on the opposite side of the coin) are often fairly repeatable for a given type of coin. Wrinkling and waviness occurs to some extent on almost all of the coins we shrink. Force imbalances are very pronounced and repeatable on certain coins, and as a result we do not offer or recommend these coins to the public. Some examples include high profile "proof" coins and older style Eagle quarters.
Unfortunately, heat treating these coins beforehand would not remove the root cause for these effects.