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The SAE milk spot's issue-"chlorine spots"??
Just been leafing thru the "grading guide for modern U.S. Coins" put out by NGC. In it they refer to "chlorine spots" sounds like 'milk spots" to me. I did a search of this on this forum and found no match (MUCH to my suprise) So a question for the chemists on the board.... what is the solvent for chlorine? -
Re: The SAE milk spot's issue-"chlorine spots"??
There is no "solvent" per sea for chlorine. The best way to counter-act it is with water. IF the milk spots are indeed a "chlorine" issue, by the time they show up, its too late to do anything about it. -
Re: The SAE milk spot's issue-"chlorine spots"??
But AgCl (silver chloride) is light sensitive like most silver salts are. Over time, the white AgCl compound darkens as silver ions are reduced back to silver metal. So if the milk spots were silver chloride, you'd see them turn darker and darker as time goes on and more of them are exposed to light. -
Re: The SAE milk spot's issue-"chlorine spots"??
If the milk spots were indeed due to chlorine origin they would likely end up on the coin in the form of chlorIDE. Any semblance of/to chlorine either from the gas or bleach would have been gone long ago. As you know or should know silver chlorIDE is a white solid substance. The haze on silver coins stored in PVC flips is… -
Re: The SAE milk spot's issue-"chlorine spots"??
<< <i>So what kind of reducing agent is readily available inside of a slab? >> Ultraviolet light. The Ag+ ion is not all that stable and readily reverts back to metallic silver in the presence of ultraviolet light. Silver Nitrate, silver chloride, silver bromide, etc. all darken over time due to the action of UV light on… -
Re: The SAE milk spot's issue-"chlorine spots"??
I would imagine in some way chlorine is used at the mint as some kinda cleaner...thus is why it shows up on the SAE's...Sun light and water are chlorine's worst enemy. -
Re: The SAE milk spot's issue-"chlorine spots"??
My understanding on this is that the "residue" at issue is stamped into the surface of the coin at minting, therefore impossible to remove. -
Re: The SAE milk spot's issue-"chlorine spots"??
the grade guarantee. -
Re: The SAE milk spot's issue-"chlorine spots"??
So what kind of reducing agent is readily available inside of a slab? -
Re: The SAE milk spot's issue-"chlorine spots"??
Yes but the Ag+ has to get its electron from smoewhere or it can't go back to Ag(0) unless it gets it from chloride which ends up as diatomic elemental chlorine or it gets it from some component of the slab itself.
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