Light Planchets, Heavy Planchets

[MoneyMaker]

Hi i'm new to this site and, well i look at a lot of coins. Every so often i find something that i'm not sure about and i have found some interesting light planchet Lincoln wheats. I find these when i'm sifting through pennies and i hear an unusual tone among them. When i find it i weigh it and these ones are lighter than normal. The following is a list of Wheats that i have found that weigh less then 3.11 grams:

1921 S- 2.82 Grams
1930 S- 2.71 Grams
1939 P- 2.74 Grams
1951 P- 2.85 Grams

So my questions are: what would be considered rare or valuable? How much over or under can a cent weigh before it is considered an error? And finally what causes a cent to weigh lighter then normal or heavier? Also these that i have listed i have inspected and there is no chance that they have been altered due to damage or acid to make them weigh less. This is something that i would like to learn more about so i would love to hear about any opinions or advice anyone has. Thanks.

P.S. I also have found a 1984 D weighing 2.68 grams, which is strange because of every zinc cent i have weighed none have been close to the 2.6 grams mark, they are always within 2.48-2.55 grams.

[GrumpyEd]

there is no chance that they have been altered due to damage or acid to make them weigh less.

Are you sure they aren't acid damaged and then circulated and re-toned?
The reason I say that is almost every copper cent I've had that made that strange clink tone has been acid damaged.
Look close for any signs like being thin, orange peel texture or thin looking details.

There is a tolerance range but I've never seen that it changes the tone.

[Shingpumps]

That's strange. Any way you could post a picture? Or maybe an approximant grade on the light wheats.

[MoneyMaker]

Thanks for your response. Here are pics of the 1921 S weighing 2.82 grams. It does have a spot on the reverse but i don't believe that would be enough to cause that much of a weight difference and it doesn't look like it affected anything but color. I have seen acid treated coins and it makes the devices seem "mushy" to me. These four i have examined very closely and i don't see any evidence of pitting or that wavy surface you get with an acid treated coin. These all show normal circulation wear and all except the 1930 S show full lines in the wheat heads, which i would think would be gone on an acid treated coin. Also the thickness is pretty much average on all four when comparing to normal cents.

[mikediamond]

Any weight lower than 3.0 grams would be considered an error for a copper-alloy cent. The usual explanation is that the planchet was punched out of rolled-thin stock. These errors can be as light as 1.4 grams. The lower the weight, the more valuable the error. The weights you cite would not add much value to the coin.

Rolled-thick planchets are less common. In copper-alloy cents these can be as heavy as 4.2 grams. Again, the heavier the cent the more valuable.

[Arjohn]

Seeing that you report "P.S. I also have found a 1984 D weighing 2.68 grams, which is strange because of every zinc cent i have weighed none have been close to the 2.6 grams mark, they are always within 2.48-2.55 grams" I have to ask if the scale is calibrated? Only because Zincs I weigh are always very near, at or slightly above the prescribed weights, and most reported here fall into that category...

[MoneyMaker]

The scale i used when i found these was an old non digital gun powder scale measuring grains and really there was no calibration needed, then i would convert to grams. I have a new digital gun powder scale that measures grams and grains and this one gives the same weights as the old one for all these coins. The majority of zinc cents i weigh come out to 2.5 or 2.49 grams usually, but i get a few that weigh a little less or more but i never get anything close to 2.6 grams.

[Arjohn]

Hmmm Yeah I'd say your scale is on point. Must be less gravity by you. My zincs go 2.52 to 2.62 the bulk 2.5 to 5.55....

[mikediamond]

A heavy zinc cent could represent a rolled-thick planchet or an unusually heavy layer of copper plating.

[MoneyMaker]

A heavy zinc cent could represent a rolled-thick planchet or an unusually heavy layer of copper plating.

Ok thanks. I appreciate all the info from everyone.