SINTERED PLANCHET ERROR?

[cnladue]

while looking at ebay errors today,I have come across a term I am not sure about.what is a SINTERED PLANCHET ERROR?

[Bob P]

Your question can be answered here:

http://www.cointalk.org/showthread.php?p=47197

If there's anything else about them that this doesn't explain, please let me know.

[mikediamond]

The whole business of "copper wash" and "sintered plating" is cloaked in confusion and myth. The copper wash appellation reflects the hypothesis that planchets pick up a coating of copper ions from a rinse bath that previously handled copper planchets. The hypothesis fails after 1982 when copper cent planchets were abandoned.

The sintered plating appellation arises from the hypothesis that planchets pick up a coating of copper dust in the annealing drum. Again, this hypothesis fails after 1982 for the same reason.

Nowadays these tend to be called "improper annealing" errors because it's thought that copper-nickel and Cu-Ni clad coins form a layer of copper on the surface when they're exposed to too much heat or exposed for too long to the heat of the annealing furnace. Exactly how this copper forms is unclear. The sintered plating hypothesis doesn't seem to work since the nickels are seldom overweight and are sometimes seriously underweight. This leaves four possibilities: 1) copper atoms migrate to the surface, forming a veneer on the coin's surface. 2) nickel atoms migrate to the interior, leaving the copper fraction behind. 3) nickel atoms are liberated from the surface, leaving the copper fraction behind. 4) copper atoms are liberated from the surface and the re-deposited as a dusting or a continuous layer.

So don't believe everything you read in the literature. We've got a lot to learn.

[cnladue]

Has anybody tested post 82 "sintered"coins to find out exactly their composition?