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The spots are due to a surface contaminant - the source is irrelevant. The chemical was organic-based, has degraded and caused the coin to tone....
Appears to be a VF-level coin, it should have no red showing. Most likely it was cleaned and retoned.
I love that! I preach it all the time when someone makes the "purity claim" (nothing more than a marketing term). That seemingly tiny bit left in...
Sometimes yes and sometimes no. There's are thousands of different metalworking operations using thousands of different types of fluid. In...
The covalently bound chlorine is not the threat to metals but it certainly is once the PVC starts to breakdown. We use various chlorinated oils in...
Too bad it appears to be corrosion rather than toning. It's still neat looking. What does the obverse look like, you're only giving us half of the...
There is no vaporization in their instrument. It is nothing like sniffers used at airports and stuff. It's simply an FTIR using Attenuated Total...
According to the PCGS website: Last I saw, it was only using FTIR Attenuated Total Reflectance. A technique that is not very sensitive at all....
DDD, very common to the issue.[ATTACH] [ATTACH]
http://www.lincolncentforum.com/forum/showthread.php?24220-The-First-Steps-to-Proper-Coin-Conservation
Unless this was merely an experiment, it was a waste of time. Just not worth the time and money. Mint state 43P's are very inexpensive. It's...
Like I said, I've never had good luck with clads. Most of them are cheap enough that it's not worth the trouble. I gave away a bunch of them to...
No idea except for the cent. This is caused by improper storage. I've seen a ton of sets ruined like this. I've only had good success with cents....
The corrosion is very thick and heavy. Any conservation effort will result in a cleaned medal IMO. The metal under the corrosion will be a...
I work in the metalworking fluid industry (20 years now) as Senior Analytical Chemist. I work with the same suppliers the Mint does. While I...
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