How can you tell the difference between a 1982 copper cent and a 1982 copper-plated zinc cent? Also, on the same coins, how can you tell the difference between a large cent and small cent?
Copper cents weigh 3.11g while the zinc cents weigh 2.5g. Here are pictures of the large and small dates Large Small Compared (Large/Small)
thanks for the replies! is there a way to tell if it's zinc or copper without the weight? because i'm kinda short a scale right now lol
You can also differentiate the zinc and copper by looking closely. Almost all of the zincs from 82 have gas bubbles under the copper plating and/or other plating issues.
I know this thread has been buried, but there is a much easier way to tell then by visual inspection or weight. If you take a copper penny and bounce it on its side it will resonate with a nice long ring. A zinc penny does not resonate, and the resulting sound is a quick "tink". Just try bouncing any pre '82 penny on a hard surface, and then do the same with a post '82 penny. Now take your '82 pennies and match the sounds.
Make your own scale! Here's mine: it cost me: two peices of plastic, some scotch tape, and any penny that is either: before 1982 or after 1982. This scale of mine works perfectly well for me!
I see two problems with a home made scale, only because the difference in weight between the pennies is so minute. For one thing, the fulcrum (pen) has to be exactly in the dead center, otherwise it will not be accurate. For another, you would have to put the two pennies at percisely the same distance from the center or their center of gravity will not match up, skewing the results. Also, what if the two coins are made of the same composition (i.e. two copper coins)? Slight differences in desity will show that one is heavier than the other giving the illusion of a different material make-up. I would mostly be worried that it would appear to say one is heavier than the other, but it is really due to a slight inaccuracy in the scale. It certainly is a good method if you can manage to measure out everything though...and safer for your coins than the bounce method (which can obviously cause anomolies with your coin). I would test it for accuracy with the bounce method first to make sure you set it up properly though.
Thanks for your posts....I needed to learn more about these (I have a tube of 82's) and appreciate you sharing your knowledge. bob
I understand those concerns . . . but in practice it's not a problem at all. Here's how I did it. 1. I taped the lever/bar to the fulcrum first. It doesn't have to be in exactly the middle, see next step. 2. I put a pre-1982 penny on one side (call it Side A), but not all the way at the end (as you can see in the picture). 3. I tested various pennies on the other side, until I achieved the following result: when a pre-1982 penny is placed on Side-B (all the way at the end), the lever goes down with a thunk; when a post-1982 penny is placed on Side-B, nothing happens. 4. If the desired result in #3 didn't happen, I kept moving the penny on Side-A -- i.e., through trial and error -- until I did get the result. The fact of the matter is this: although the differences in weight seems slight (2.5 g to 3.1 g), the copper penny actually weighs *over 20% more* than the zinc penny. This is more than enough tolerance to get the lever working properly. All I can do is tell you from experience -- I use my home made "machine" on all my 1982 cents, and the results are exceedingly unambiguous. Furthermore, with various people cleaning up (wife) and playing with stuff (kids), the "machine" often loses it's calibration -- and it takes me all of 20 seconds or so to re-set it.
To get an idea of how much that 20% difference means, if you took a one foot ruler, put your fulcrum at the 6 inch mark and lay a zinc cent on it so it was centered over the 1/2 inch mark you would have to put another zinc at the 11 1/2 mark to balance it. But a copper cent would balance it it it was centered over the 8 1/4 inch mark. That is a difference of 3 1/4 inches in placement. So if you put an unknown piece at say the 10 inch mark, if it is copper it will go CLUNK because you are well past the balance point. If it is zinc it won't move because you aren't even close to the balance point yet. A lot of people use popsicle sticks or shorter 6 inch rulers but the longer lever arms of the foot ruler gives you a much greater difference in the position of the balance points. On a six inch ruler with a zinc on the 1/2 inch, a zinc balances at 5 1/2, but a copper balances at 4 1/8. A difference of only 1 3/8 inches.
Wow! That's awesome...I had no idea it would work so well. I can't wait to try that out. I still suggest trying the bounce method though. You get your results instantly without having to build anything! The difference in sound is very easily distinguishable.
