Many of the good looking zincers (look like Cu cents, no blisters) end up weighing just under the max tolerance 2.6 (2.5+0.1) when I check them. This indicates to me that the variance is better thickness of copper. This one is over Zn tolerance, but under the min for a Cu planchet 2.98 (3.11- 0.13). I suppose it is just more extra Cu and just Zn inside. But, it is over tolerance by about an additional tolerance unit.
The mint used three different suppliers in the early zinc days. Each one was assigned a different size spec of copper inside the zinc so junky planchets could be traced back to them. The copper was also suppose to help the copper wash adhere better to the zinc. Maybe the one with the biggest specs had the best looking planchets?
This is news to me. Not sure what you mean by 'copper inside the zinc'? I thought the spec was 2.5 +/- 0.1? Do you have any thing on these different size spec things?
Ooopsie. I meant specks, as in bits of copper in the planchet. I think I read it in ETCM long, long ago. I'm not sure how they could do it, but that's the story and I'm sticking to it.
The 1982's used pure zinc for the cores but later ones have a trace of copper included in the cores, it helps the plating adhere better and reduced the plating blistering problem. A weight of 2.98 grams is seriously out of spec for a zincer. Have you run a specific gravity on it? It might be a foreign planchet.
Is there a list some where of the weights of foreign planchets for the year? I have not tested it. Probably no big deal to be over weight, right?
The mint stopped coining for other countries in 1984. I haven't been able to find what the last coins they made were. Also the planchet producers also made planchets for other countries so it is possible for a foreign planchet to become mixed in with the US planchets and there would be no US mint specs for it's weight.
