Monroe sintered dollar mystery solved.
packers88
Posts: 558
I just saw on the coin world website that maganese oxide was the culprit. I buy these issues from a coin store and he doesn't have the newest issue until friday. IF someone has an online subscription to coin world can you please cut and paste the full article here. I have some of these monroe sintered dollars and I'm curious as to what the article says. I've been wondering myself for months now what caused these dollars to be black as opposed to gold. These are fascinating coins if you see one in person. Some are extremely dark or almost a pitch black and some are just a light coating that really don't look that fascinating. When you put the really dark ones next to a normal monroe dollar it looks like the strike was done on a totally different metal.
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If this is really the case, I wonder why there aren't more blackened Wartime Nickels which had a much higher percentage of Manganese?
Once again, Chris Pilliod throws his opinion into the ring.
To me, it appears that he had his own theory regarding these and then set about to proving it.
The name is LEE!
Carol
The name is LEE!
The name is LEE!
<< <i>The brass that pres bucks are made of contains manganese. The problem occurrs when oxygen in introduced during annealing. --Jerry >>
Pilliod actually states that this could have occured at "any time" during the manufacturing process or under "typical environmental conditions". So the question arises, will, under "typical environmental conditions" a lot of Presidential and Sacajawea dollars begin to exhibit this condition?
The name is LEE!
It didn’t happen with war nickels because the coins were a single alloy and annealing temperature was different.
<< <i>Oxide dust adhering to a planchet is not “sintering.”
It didn’t happen with war nickels because the coins were a single alloy and annealing temperature was different. >>
Then, exactly what would sintering be Roger?
Wouldn't the annealing temperature have been higher for the Silver Nickels or is Silver not as hard as copper?
<< <i>So could someone give a summary of the article or pm me the article. Does the article conclude whether or not these are improperly annealed/sintering or some other type of terminology besides maganese oxide? Thanks >>
You'll have to wait on the article but it does not mention "sintering" or "improper annealing", only manganese oxide. How the TPG's will respond to this is unknown.
The name is LEE!
The name is LEE!
It didn’t happen with war nickels because the coins were a single alloy and annealing temperature was different.
This is all correct. I did not read the article, but several things here:
1. Sintering is an actual bonding of materials on an atomic level
2. War nickels were made of one homogeneous alloy, the vast percentage being silver. Not much experience with silver phase diagrams or silver heat treating, but I would presume the alloy does not readily oxidize at whatever the annealing temperature was, even if exposed to or annealed in atmosphere.
3. What particular annealing process is used on the manganese brass dollars - as in what temperature, annealed in atmosphere, vacuum, or other inert gas? MUST know that information before making ANY determination of what questions to ask. Were the planchets removed from the furnace before they were below a certain temperature range? Were they done in vacuum and did the furnace have a leak and allow atmosphere to attack the planchets while at an eleveated temperature? Did the furnace run a cycle at too high a temperature? Did they get stuck in the annealing furnace and have over-extended cycle time? These are all very feasible possiblities. Many questions to answer here, and probably many more yet un-asked.
For example, there have been thousands of Monroe dollars released which exhibit this darkening. However this is not limited to the Monroe coins as a few have been found with the Washingtons and the Adams coins as well.
My guess is that something happened to create enough of these in one batch so that literally thousands of them could be found in a localized part of the country. This tells me that parhaps the QA Inspector at both the mint and the rolling facilities were "unavailable" because a quantity such as what has been reported would surely have caused them to be pulled. After all, its not like the average Joe COULDN'T pick these out from the rest of the crowd simply at a glance.
Another thought could be that these are somehow linked to the Monroe coins tghat were minted on the quarter planchets.
Nah................
The name is LEE!
I do back you that the answer lies with the Mint. I don't know Chris Polliard or however you spell it, but I'm sure he does have a strong back ground in this field, but it would sure be nice to hear from the Mint about these coins and what their guess is. I found these myself and I heard of other experiences here in Michigan and from what I gathered these were found only at 2 banks and all finds were within about a 30 mile radius of downtown detroit, so these did indeed orginate from a certain batch and something did go wrong at a specific time for x amount of minutes or hours. In other words, and abberation did occur at one time as opposed to over and over again during different times and I believe the evidence of limited geographic areas backs this up. I don't have enough educational background on how the production process of coins works to speculate where or how this error occured, so I can't refute any arguments from Chris or anyone on this board, but once again I do knnow that the really dark coins I have are probably the neatest errors I have and I do have some leafs, smooth edges, clipped edges, and double lettering coins.
As I stated, I can't help but wonder why this is coming up now asince these have been around since the Washington Dollars, just not in such large quantities. I'm in support of finding the truth but the general consensus has always been "sintered planchet". Fred even has some on his site.
The TPG's will grade them as error's, but the first question will be, "What Kind of Error?". The second question will be "What do we do with those that are graded as sintered planchets?"
The name is LEE!
<< <i>
The TPG's will grade them as error's, but the first question will be, "What Kind of Error?". The second question will be "What do we do with those that are graded as sintered planchets?"
Llyds, I agree that they will still grade them as errors and as far as I'm concerned an error is an error regardless of the story behind it. Personally, I wouldn't mind seeing "manganese oxidation mint error" on the holders and to me this would sound even better than improperly annealed mint error or improper alloy mix. Either way these coins are really neat and for me I would much rather show these coins off in some kind of holder with a catchy name. Not only would this be neat to have, but also it would probably enhance the value when I sell any down the road.
<< <i>............... but also it would probably enhance the value when I sell any down the road. >>
All except those thousands of Monroe's!
But, those could generate interest in the Washington's, which are not that common, and the Adams coins which again, are not that common.
I'm actually kinda surprised that more of the Monroe's haven;t shown up on eBay!
The name is LEE!