1990-p sintered planchet

[THE PENNY MAN]

Hello all just found in bank roll, i think this is a sintered planchet. Please let me know, thank you.

[mustbebob]

I am not sure, but I believe a sintered planchet would affect the entire planchet, not just a portion of it. This coin looks like it was dipped in a liquid of some sort.

[jcuve]

From what I understood Sintered Planchets are the product of a batch of non-copper planchets being annealed in the same furnace immediately following a batch of copper (or copper plated) planchets having recently been annealed. The idea was copper residue in the form of dust or small particles having been left behind, could hypothetically become adhered to the non-copper planchets - if - those planchets were left inside the annealing furnace too long and the particles melted onto parts of the planchets inside. The result would be a copper wash of blackened copper particles on the whole or part of the surface of the planchet.

What I don't know is if a similar process can occur with copper or copper plated planchets, thus the coin shown doesn't fit the model described and is either not a Sintered Planchet or one requiring another explanation.

POSTSCRIPT: putting my comments from above to the side, I agree with Bob (who commented faster than me) it doesn't look right - it does appear dipped and thus chemically altered from what ever it was dipped into as opposed to the whole coin or one side of the coin being Sintered.

[THE PENNY MAN]

Thank you both for your knowledge.

[Wheat Cents]

Maybe dipped . Certainly a matching OBV REV on coin

[mikediamond]

It can't be sintered plating because zinc planchets are not annealed, either before or after plating. Sintering itself is a myth as is copper wash. For the real story, visit the CONECA website: www.conecaonline.org.

[jcuve]

It can't be sintered plating because zinc planchets are not annealed, either before or after plating. Sintering itself is a myth as is copper wash. For the real story, visit the CONECA website: www.conecaonline.org.

Improper Annealing - wow - no Sintered Planchets! Very interesting and well written investigation into this numismatic mystery Mike. Sorry I missed the article when it first went up, but at least this particular inquiry here at LCR ended up being a perfect segue to that paper at CONECA.