I was looking for information about the laser technique the Mint uses to produce frosted devices on US proof coins and I found a few items that may be of interest. I assume the frosting (texturing) is applied to the die, not the coin. Does anyone know how this texturing stands up to the minting process? In other words, how often is a die "textured" and do early strikes differ noticeably from later ones? A brochure from the FOBA company A company that makes laser marking and engraving machinery...frosting and surface texturing being one of the steps. I don't know what the Mint uses, but thought this was interesting. Some pictures from the Canadian Mint's laser frosting efforts...
I suppose the easiest way to answer 1 of your questions would be for you to look at the Proofs from 1936 to 1972. Finding cameo coins from this period is quite difficult, thus the "texture", which is what causes the cameo, doesn't last very long and the early strikes differ greatly from the later strikes. Now I know the dies in this period were not textured with a laser, which is what you are asking about. But the method used to texture the dies doesn't matter much. The only thing that really matters is how long that texture lasts. From what I have read, it lasts for a couple thousand strikes at best.
Interesting...that's what I was thinking, also. I've noticed that there's a higher percentage of PF70s since the new process was adopted...as compared to just ten (10) years earlier. If you look at the Silver Proof States Quarter population reports, the number of PF70 doubled around 2005. Perhaps more were being submitted, but that's quite a coincidence. I'm not quite sure what to make of that. Personally, I feel the results of the new process to be less eye appealing...more granular, but I haven't studied enough laser textured coins to identify variations...but there must be variations (I would think). Do you know how many times a proof die is retextured before it's replaced? ...or do they just get a couple of thousand strikes from each die pair before discarding them? Thanks!
The population of 70s increased because of changes to the grading standards used by the TPGs. It had nothing to do with the coins. Starting in 1973 the mint changed their methods in regard to making sure that the Proofs were all cameo. Prior to that, they didn't care if the Proofs turned out cameo or not. After that, they made sure that they were all cameo. Granted, there were a few shortly after the change that had a poor cameo quality. By by the late '70s they all were. There are some differences between the cameo coins of various years due to the different methods used to treat the dies. Some were sand blasted, some were acid etched, and now they use lasers. So of course the texture is going to be slightly different. But the net effect is the same. But the way that use of the dies wears that textured finish off was pretty much the same regardless of what method was used to create the finish. As to how many times a Proof die is re-textured, I have no idea. But the determining factor is the polishing of the fields. Once that polishing wears the die fields down low enough that the the relief is no longer there, or that the polishing will begin to intrude on the devices - then the die is discarded. The mint doesn't really give us numbers regarding how many coins each die makes or how many times a die is re-surfaced, they just give us rough estimates in some of the comments they make.
...so, if I resubmit my 1999 PF69 UCAM Delaware quarters, they should come back PF70 UCAM? :hail: One question keeps coming to mind when I look at the pictures of the Canadian Mint proofs above. Are the differences the result of texture deterioration or is it the result of "Operator Error" setting up the machine? I guess government "transparency" ends at the steps of the US Mint. :headbang: Thanks for the insight! :thumb:
If you wanted to play the crack out game some probably would. There's more going on with those Canadian Proofs than just the texture of the frost. There's 2 possibilities - either the designs were slightly changed, which is not unusual given as they are all different coins. Or the examples used in those pictures come from different die states. Either one could explain the differences in the frost. It always has. The mint has always refused to release information like that for fear of creating rarities in the minds of collectors.
Does anyone know how the Royal Mint in England made there proof dies in the early 30's to the late 40's and as well as there other branch Mints.
Sorry about that....what I meant to say was,,,How did they prep the dies for producing the proof effect where they acid treated, polished, etc etc. and if you know the answer...How did they look or compare to proof coins made in the 50's. what I'm trying to find out is how my Icelandic proof coins from 1940 was made since Royal Mint in England made them and how they differ from other proof coins from the 50's made from the same mint or other mints int England from those periods. I hope I have not confussed you by now...:scratch: Any info would be great,,,or if you know of a book that can help explain the minting pratices of the royal mint in England.
I can't give you a definitive answer because I don't think anyone knows. There were 2 methods employed by the various mints around the world to produce the cameo effect on the devices of Proof coins - sandblasting and acid etching. Sandblasting was invented in 1870, so coins dated before that were obviously etched by acid. But after that, the mints were switching back and forth from time to time basically on the whim of whoever was in charge at the time. Polishing was the universal method of producing the mirrored or mirror like fields.
