Is it me or are the zinc Lincoln cents before 1996 have a better copper plating because they seem to hold up better than the newer ones.
The 80s cents are the worst. Loaded with plating blisters and split plating around the date, MM, and letters
Supposedly fhe mint changed the specs slightly after the first couple years. I haven't read that they changed them later on.
Definitely not. I have seen way too many zincolns and they all have the same problem... ZINC! Possibly what you are seeing are pre 1996 cents turning brown and accumulating a nice layer of skin oils and gunk giving the impression that the copper coating is thicker than it actually is. It isnt, they are are just getting older and dirtier.
Yes, I’ve seen some 1983 reverse side doubled die cents for which I would not have paid a dime. The plating was blistered and the air was rushing in on the zinc. Under the worst circumstances you could put that thing away, and come back a decade later to find that you had an envelope full of dust.
I doubt the specs were changed. I certainly haven't heard that before. When zinc was first used and coated with a super thin coat of copper all sorts of problems occurred. While these problems have gotten better than the 1980's they still persist today. Why? Because the Cents are made of zinc.
I read - but can't find - that it was a tiny change, something like making the plating 0.003" instead of 0.0025" ... Jarden Zinc and the Mint have not disclosed the true specs anywhere I've been able to find them.
as of a 2012 metal study usmint documents, the cent is still listed as having a 8 micron thin copper plating; such as they had at the beginning. I have read non-USMINT related articles speculating various thicknesses. Consol.com ?? in a electroplating article states it's 20 microns or something.
8 microns is 0.000315 inches not 0.003... I'll accept that... The problem is the math doesn't work. The core is 99.2% zinc in 0.8% copper, but the entire coin is described as 97.5% zink 2.5% copper. This from ats calculates the weight as 0.0251g - https://www.coincommunity.com/forum/topic.asp?TOPIC_ID=291160 Subtract the 0.251g from the 2.5g nominal weight gives 2.4749g at the 99.2%/0.8% or 2.4551g and 0.0198g. Add back the 0.0251g and calculate the resulting percentages gives 98.2% zinc and 1.8% copper not 97.5%/2.5% In order for those #s to be correct, the plating would need to be about 67% thicker or just over 13 microns...
I have no idea. I didn't check that link but don't forget the "surface" of the coin is not flat. it has all the up/across/down of each letter adding significant surface area. Also, there's a lot of problems that have to be solved for plating, such as on a flat surface one can control the thickness. On curved, or edged surfaces the thickness varies usually too thick. So maybe the "target" on the flat areas is 8 micron, but due to the plating problems (and how much they wanted to solve) the add'l weight is taken into account. at this point it would be best to involve a plating engineer, preferably one of the mint's suppliers for an accurate response. and maybe the percentages are just rounded ?? i didn't make them to know their accuracy.
The plating happens before the strike, so the model as a simple cylinder is pretty accurate. Yes, the upset rim is part of the zinc core before plating, so there would be a tiny bit of thinning there. Even if the quoted %s are rounded, the discrepancy is still more than the loss of accuracy.
true, have you tried emailing one of the planchet suppliers for a response? We're just guessing / speculating about it otherwise.
