Copper luster question
Shoedog
Posts: 136
Can anyone explain why some uncirculated coins are seldom found with luster? I'm thinking in particular of 1857 Half Cents. I know flowlines in the dies are the cause of luster so could there be a reason these dies didn't flowline. I realize this is a low mintage issue but I suspect this flowlining occurs fairly quickly.
Thanks.
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Comments
<< <i> Can anyone explain why some uncirculated coins are seldom found with luster? >>
People often assume (wrongly) that every coins ever minted has luster. Keep in mind that it's quite possible that poorly prepared planchets may have very poor (oxidized) surfaces to begin with making luster nearly impossible to produce.
michael
<< <i> I was thinking the flowlines on the coin cause luster. >>
Not necessarily. Flowlines give the coin a frosty appearance, but if the planchet is crummy to begin with, there's not much hope.
Another good question!
Luster can be defined as the light reflected off of radial flowlines eminating from the center of a coin. The flowlines are the bi-product of excessive force/speed needed to strike a coin. The magnitude/intensity of the flowlines will depend on many factors, including but not limited to: size of the planchet, metallic properties, planchet preparation, force of the strike, speed of the strike, etc.
Some very well struck coins do NOT have luster (flowlines). For example, consider a modern proof coin that has mirrored fields. Why mirrored fields? 1) because of the specially prepared planchet and, 2) because of the much slower speed of the press, despite the obviously higher striking pressure.
You commented that "flowlines in the dies are the cause of luster", but it is not the dies that are flowlined, but rather the individual coins once struck. Remember that the working dies were hardened after preparation, and therefore would not likely pickup flowlines from multiple strikes. Flowlining (aka luster) on coins will and does vary from coin-to-coin. Have you ever seen 2 identical date Walking Liberty Halves sitting next to each other, both grading about the same, but one has much heavier luster? Assuming that neither coin has been cleaned, and both are truly mint state, we conclude that the more lustrous coin was struck with more pressure and/or at a greater press speed.
The 1857 half cent that you mentioned is just one of many coins that are known to not possess much luster. In the case of the 1857 half cent, I would guess that they were struck at a slower speed, hence the less obvious flowlining. Also you must remember that the mint only used one set of dies for the 1857 (C-1) to strike both proofs and business strikes. After striking the proofs, did the mint change the press set-up, or just continue striking business strikes on normal planchets? My guess is that the Mint just continued striking 1857 business strikes after the 200 or so proofs that were struck. I mean, why waste the time to change the press set-up? Just throw in the normal planchets for business strikes and start minting. That's why it can be very difficult to distinguish between an 1857 proof and a business strike.
The lesson here is that a coin lacking luster does not necessarily mean that it is of a lesser grade. The trick to determining the appropriate mint state grade on an uncirculated coin is in trying to establish how close the coin is to its original condition when struck. On 1857 half cents, grade on the strike and the originality of the surfaces.
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<< <i>
<< <i> I was thinking the flowlines on the coin cause luster. >>
Not necessarily. Flowlines give the coin a frosty appearance, but if the planchet is crummy to begin with, there's not much hope. >>
Not necessarily?
Get real. Read my statement again and think about it.
If flowlines are not the cause of luster just what is?
Sorry for the confusion.