How do proof coins become not cameo?
CoinPhysicist
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This is a dumb question, but what's the deal with non cameo proofs?
For example, if I take a brand new DCAM (Ultra Cam) proof (say a 2018 Half Dollar), will it over time turn into an only cameo proof and eventually to a proof with no cameo? If so, under what conditions does this happen? And if not, how are some proofs made to be more cameo than others?
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If it does happen, one cause is improper storage damaging the coin in the holder.
bob
Would be interesting to hear how the dies become non cameo as they get used.
Long story short. The proof dies were treated in an acid solution to create a frosted surface. The fields were then polished to a mirror finish. Remember the devices are below the surface of the die, so this is pretty easy to do to create the cameo effect on the die. The polished planchets are then struck by the die which imparts the frosted finish to the devices on the final product. Unfortunately, the frosted die wears relatively quickly so the degree of frost lessens with every strike. Ultimately, the die strikes a brilliant proof.
Dies can be re-etched and polished. Examples are relatively easy to spot by looking for die polishing lines on the devices.
The best photo I have seen on die progression is in Rick Tomaska's book "Cameo and Brilliant Proof Coinage of the 1950 to 1970 Era". I don't think he would mind that I posted a photo. There is a similar photo for the reverse, but you get the idea.
“In matters of style, swim with the current; in matters of principle, stand like a rock." - Thomas Jefferson
My digital cameo album 1950-64 Cameos - take a look!
To more directly answer the question: A brand new 2018 dcam half dollar will stay that way unless you do something to wear the surface away. It won't cease to become a cameo on its own. These days, the mint uses a different materials and a different process to frost the dies which lasts much longer in production. So there is still a die wear progression, but the mint changes the dies to limit release of cameos with low contrast.
These improvements in die processing are the reason why it is hard to find a brilliant proof coin after the mid-70's.
“In matters of style, swim with the current; in matters of principle, stand like a rock." - Thomas Jefferson
My digital cameo album 1950-64 Cameos - take a look!
Interesting, thanks for the answer @Cameonut. Definitely an appropriate username. Is this why there are so few walking liberty halves in cameo proof? Because of the wear on the dies?
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In that era, the mint was not very interested in making cameos, but they do exist in very small quantities for some dates and denominations. My suspicion is that they didn't etch the dies that much so there was never much frost on the dies - thus little or none on the coins. Perhaps enough to strike a few cameos before the frost wore off. I don't think it was a matter of die wear- the frost probably wasn't there in the first place.
Edited to add: Tomaska's book (referenced above) devotes all of Chapter 2 to the minting process. 8 pages in length, of which 3 directly relate to die prep and striking.
“In matters of style, swim with the current; in matters of principle, stand like a rock." - Thomas Jefferson
My digital cameo album 1950-64 Cameos - take a look!
Great information to share, thanks !!!
You will also find detailed descriptions and die parings related to cameo proofs (1936-1942) in the book United States Proof Coins - 1936-1942.
Many dies are prepared for minting and the first 100 coins, or so, off a die will be DMPL or PL, beyond that just BU.
bob
Tomaska gives me the creeps. A kid getting into dad's collection and putting the ucams into circulation will remove the cameo effect pretty quickly.
UCAM's, DCAM's and CAM's seem to be in more demand lately... and the prices on certain one's have definitely gone up very fast. While looking for a specific coin yesterday, I noticed I have several UCAM's/DCAM's slabbed that I acquired years ago. I must revisit the pricing on these - totally forgot about them. Cheers, RickO
Cameo coins tend to keep at least part of their cameo surface even when circulated. Prior to a certain date (I don't wish to get specific w/o making sure of the date) most proof coins did not have a cameo contrast to begin with. That's why any cameos were very scarce. This made them popular with many collectors. I guess the Mint took the hint and now, finding a Proof that is not cameo would probably be impossible.
I thought circulation would take cameo away quickly. Learn something everyday. Thanks.
The cameo is on the lowest part of the die and the highest part of the coin. Let's speed up the circulation process. Imagine a frosty headed Jefferson nickel. No we start scraping it across a concrete floor. The highest area of cameo will disappear quickly but the area (lower on the coin) near the edge of the cameo head will still survive the abuse for much longer.
once a coin is struck it will retain its Cameo appearance, the "frost" won't fade since it is imparted to the planchet surface by the dies. there are two things which might alter the appearance, wear and haze. if a Cameo coin is stored properly it will retain that appearance in infinitum barring damage from natural conditions.
striking coins with a Cameo appearance is the highest form of the Minting Art. the Mint had to learn how to do it, but if you look in CoinFacts you can see that there are Cameo and Deep Cameo coins from the early part of the 19th Century. even with what might now be considered primitive methods, the coiners were able to produce that beautiful finish by preparing the dies properly. they stopped around 1909 and went to a Matte/Sandblast finish and then stopped making Proof coins altogether.
that is when the trouble began.
when the Mint once again started to make Proof coins in 1936 there was no one left that knew how to do it, they had to re-learn the process. they figured it out but hadn't perfected it when the Proof production ceased in 1942. when they started in 1950 the process seemed to improve a little each year. according to Rick Tomaska, the dies were "pickled" with a weak acid, probably Muriatic or weak Nitric, and then the highest surface(the fields) polished to high brilliance. in his book he notes some of the best dies for each year/denomination but I have never been able to decipher what he's talking about.
the frost wore away quickly and the struck coins went from Deep Cameo to Cameo to Brilliant most probably within 100 strikes. sometimes the dies were reworked, but more often than not they were just used to strike brilliant coins or had the fields re-polished.
in the early 1970's the Mint started to chrome plate the dies to get a Deep Cameo/Cameo finish on virtually every strike. if you want a nice example of this "Art Form" I would suggest a 1956 Franklin Half Dollar already graded by PCGS or search 1962 Proof Sets for a nice Half-Dollar. for the later process, I think the best years are probably in the mid-1980's, 1984-1986 are incredible looking examples of Deep Cameo on every coin in the set. they are very inexpensive.
--- if I am wrong in any of my facts, please correct them
Another great example of the quality and value of this forum. I just learned more in five minutes than I've learned in 30 years about cameo proofs. Thanks to all the experts.....
And great question to ask.
I understand what you are saying. CU is a gold mine. Nevertheless, the information posted above provides a good summary of information that has been available to you or anyone else interested in Cameo Proofs for years. Keets and many of us have found it in the Tomaska book and in several other places. These days, just about anything you are interested in can be found with very little effort. Now go buy the book.
Soon, you'll be posting as Keets has.
RE: "in the early 1970's the Mint started to chrome plate the dies to get a Deep Cameo/Cameo finish on virtually every strike."
The first US Mint chromium plating tests were made in 1926 using equipment transferred from BEP. Some foreign dies and US coin collar dies were plated in the 1930s and evidently a few proof dies were also plated. In 1943 most cent dies were chromium plated by the National Bureau of Standards. Chromium improved die life and also reduced problems of coin release for zinc coated steel cents.
Note that the final step before use of coinage dies (all dies) was a quick surface dip in weak nitric acid. This was intended to dissolve surface oxides creating during final hardening and tempering. A brilliant proof die was made by polishing the (raised) field (or 'table') of a normal die. This created coins with a brilliant field and lightly frosted relief - what is now called a "cameo." It was not intentional until sometime in the latter 1950s.
As mentioned, this is covered in detail the 1936-1942 Proof Coin book.
Roger, how did the Mint achieve this finish back in the 1800's??
I was involved in the purchase of five 1927 5c "Special Strike" raw coins when they appeared in multi-coin lots at a Harmer-Rooke auction 30 years ago. The reverse dies were easily recognizable as being from the master die of the group used exclusively only for Type II proofs, and the finish was "unusual but kosher", This was the observation of the several dealers in the audience who colluded as the coins were bought for nada. I got bought out the next day and forgot about it.
It was more than a decade later when documentation was found that established the use of the chromium-plated dies @Rogerb describes. And I went Aha!
And I continue to listen.
Best I could do in 27+ years........but it's still eye candy.
Leo
The more qualities observed in a coin, the more desirable that coin becomes!
My Jefferson Nickel Collection
RE: "Roger, how did the Mint achieve this finish back in the 1800's??"
Much the same way. An overview of 19th century US and British proofs indicate that there was more attention paid to maintaining frosted/non-polished relief. Friskets were commonly used in Britain and France to alternatively mask relief and field before sandblasting relief areas. I recall a reference (British, I think) to filling die relief with a putty-like material to facilitate uniform polishing field polishing. However, I've found nothing definitive for the Philadelphia Mint that that period.
Engraver of the United States Mint at Philadelphia, John Mercanti, has described the use of friskets for 1969 and later proof coins. This required careful work and must have been a chore at a time when proofs were made by the millions. This process was replaced with laser texturing, which produced a coarse, unnatural frosting often called "snake skin." It is only within the past year or two that laser frosting has begun to approach the quality of traditional sandblasting.