Matte Finish - Is it sand blasted?
dlimb2
Posts: 3,449
Does anyone know how they do this? Thank You.
0
dlimb2
Posts: 3,449
Comments
as a `brilliant proof` does.
Sandblast in quotations may mean the dies ARE actually sandblasted to give this grainy surface.
How else would they achieve this I,m wondering.
I,d say ,yes, the dies are lightly sandblasted.
While the exact technique is not known (or maybe published)... it is widely thought that there were three or four different methods of production for these coins.
Sandblasting I believe took place AFTER the coin was struck. For the 1909 and 1910 dates (and maybe another, I've forgotten) there might have been some sort of acid "pickling" process to get the satin/roman finishes of those dates...
I love those coins, and used to own for a short while a PF 66 1914 quarter eagle. Wish I still had it..
V/r,
John
siliconvalleycoins.com
siliconvalleycoins.com
Come on over ... to The Dark Side!
Come on over ... to The Dark Side!
"The dies for conventional, brilliant proofs such as those coined in 1903 were polished to a fine, mirror-like finish. There was, however, a sandblasting chamber which was used to dull the finish of medals so that their design might be more easily studied without glare. This technique, pioneered at the Paris Mint only a few years before, was gaining a growing acceptance among coiners and medallists. It had been used in preparing the proof set of 1902 marking the coronation of England's King Edward VII."
"The practice of sandblasting had yet to be extended to actual coins at the Philadelphia Mint, but the necessary device was already in place. (James Rankin) Young described it as 'a small wooden box with glass sides. A pipe on the inside blows down a fine shower of sand. The operator, wearing a big pair of mits to protect his hands, holds the coin (medal) under this stream of sand until the operation is finished, when it has a delicate frosted appearance.' "
"Dies too were sandblasted to give them a textured surface, followed by a vigorous polishing of just their flat fields. This resulted in a contrast between brilliant fields and frosted cavities which was imparted to the finished coins. These were the frosted proofs so popular with collectors of the late 19th and early 20th Centuries."
"Also a common practice at the U.S. Mint was the cleansing in acid of coin and medal planchets. This removed any residual grease or oxidation which may have accrued from the casting, rolling and planchet-punching processes. These planchets were then dried by tumbling them within sawdust and polished by additional tumbling against one another, sometimes with the assistance of metallic beads."
"The combined application of sandblasting and acid baths is believed to have been behind the matte proofs coined 1908-1916, as the new designs introduced beginning in 1907, with their sculpted surfaces and irregular fields, did not lend themselves to the traditional method of proofing. The French matte process was thus applied in 1908 and subsequent years, though both the methods and the results varied somewhat from year to year. There appear to be only two variant finishes on early proof Lincoln cents, the true matte finish and the softer satin finish. It's not known for certain whether these two variants were the product of intent or a simple evolution. The author believes that the satin proofs were simply coined from the same dies as the matte proofs, but after these dies had lost their rough texture from very slight wear and additional polishing."
"If sandblasting was used in the manufacture of proof Lincolns, it was probably in the die finishing process and not with the struck coins themselves. Even at that, the sand must have been extremely fine so as to not diminish any of the subtle details found on these coins. There is also no real evidence that acid was used on the struck coins, though it was undoubtedly a step in the normal cleansing of the unstruck planchets."
"In short, we simply don't know exactly how the proof cents of 1909-1916 were made. Some subtle distinctions appear within particular dates and from one date to the next."
09/07/2006
Thanks...
siliconvalleycoins.com