DMPL Morgans and Pickling Acid

FC57Coins

I was at my local coin shop yesterday looking at a beautiful 1884-O DMPL Morgan dollar with cameo features and the dealer, whom I've known for some years now, started to talk about why branch mint Morgans were more often found in this condition than Philadelphia examples. As he tells it, the branch mints would receive their allotment of dies at the beginning of each year, and, to avoid rusting, some of these dies would be put in "pickling acid" to conserve them. Over the time that these dies stayed submerged in the concoction, the surfaces of the die would become etched. When the dies were ready to be used, mint employees would grind the face of each die to a polished finish, and thus the first several coins made from those dies would come out as these gems. I was wondering if some of you Morgan pros had heard of this story or other similar annecdotes. I found it pretty interesting.

Regards,

Frank

agentjim007

Just by your story if they could polish away the etched surface why couldn't they polish away any rust? I think maybe that dealers been drinking the pickling acid.

Gilbert

Earlier frosted devices were prepared similarly, although, it is my understanding that the acid was applied to the devices; not stored in it. This method produced very delicate cameos that didn't strike as many cameo'd coins AND is so delicate that it can be scraped off a coin. All proofs need delicate handling, but the earlier proofs moreso.

BTW, some coins are also altered in this way (pickling the devices) to present the appearance of being a proof, or to enhance a brilliant proof.

Dog97

It's a good story but the cameo frost comes from the master die used to make the working dies, not from pickle juice. The Branch Mints struck less coins per die than the P Mint making CC, O & S DMPLs more common. Polishing the dies right before installing them in the press is the basining process. Dies were also repolished from time to time which made them strike DMPLs again.

MrLee

Hey Frank. Did he ask you if you wanted to go Snipe hunting?

Coulport

The proper method for storing tool steel is with a coating of oil.
They knew it then and they do it now.

Gilbert

Point of clarification.

"... During the earlier 1950-1970 era, however, the dies were instead dipped (some refer to this process as 'pickling') in a bath consisting of five percent nitric acid and 95% alcohol. This pickling technique created a very light, delicate frosting over the entire surface of the die. The worker preparing the die would then double-check the frost in the devices of the die for irregularities or unevenness, and take a cotton swab dipped in the same acid/alcohol bath to "frost up" any weak areas."

re: proof die preparation of the aforementioned era (1950 - 1970) before the advent of sandblasted and chrome plating of dies for modern proof production, "were very similar to those performed in proof manufacturing at the turn of the century."

Cameo and Brilliant Proof Coinage of the 1950 to 1970 Era, by Rick Jerry Tomaska

FlyTooHigh

I have to agree with Coulport about the method of preserving tool steel dies - not only ones used for coins , but other dies in manufacturing. Oil, and other hydrocarbon preservitive derivites, are commomly used to keep die surfaces from corroding. And they do this quite nicely. I find it hard to believe that acid based solutions were used to keep "expensive" die surfaces preserved. Makes no sense? The Mint is no exception. Why pay die men, tons of money to make dies and then place them in solutions that will degrade the work they did? Then, try to fix the dies? Idiotic!

Coments welcome...

Tony

Gilbert

But who is saying that the mint is "preserving" dies in a destructive manner? The initial question was, well, it's right there to be read.

FC57Coins, I hope I 've provided a little basis for was was probably a misinterpretation of what "pickling" of dies really was.

Conder101

Just a guess here but during the hardening process of the dies is it possible that the quenching was done in an acid solution? I know quenching in differnt types of liquid can impart different qualities to the item in terms of hardness, finish, etc. Possibly as part of the hardening process the dies were quenched in acid which also provided the frosted surface to the die. Then polishing or basining would remove it from the fields giving the cameo appearance. As for storing the dies in a acid solution I seriously doubt it. The mint gets in a six month or a years supply of dies and puts them all in acid for storage? What are the last dies going to look like when they pull them out 6 months to a year later?