Damage or Oxidation to Silver Coin

That flip looks like one of those soft pvc flips which itself could be toning the coin.

 

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It is toning. Remove it with a coin dip. I agree with @Suarez it is interaction with Sulphur, most likely paper but any paper source. Fresh silver is very susceptible to this.

Its pretty black, you better hope its still what I call "shiny black" toning which will most of the time not leave behind damage. "Matte black" almost always means the surface underneath will be damaged by the corrosion.

I would grab some coin dip, grab junk silver, and play with time-strength. A good dip should be something just strong enough to remove the toning and not any stronger. Coin dip by definition removes a thin layer of surface metal. Done right no one knows, overdipped and the coin will lose its luster.

 

Not to be too pedantic in turn -- oh, what the heck, I'm being pedantic.

Oxidation doesn't just mean "combining with oxygen". Oxygen, sulfur, and chlorine can each oxidize silver. They combine with the silver to form a compound where the silver has a positive charge (has lost electrons). That disrupts the metallic surface -- instead of being part of the surface, those silver atoms are now stuck in compounds.

You can reduce the silver, turning it back into silver metal, but you can't put it back in the same place on the surface that it came from. Most dips don't do that anyhow -- instead, they take away the silver that's already reacted, along with the stuff it's reacted with. Many dips will also remove more metal from the surface, especially if you use them too long, or at the wrong strength, or without removing/neutralizing them afterward.

 

Thanks for correcting me Jeff, I didn't know this bit :- )

 

And thanks for your patience. I suppose I'll always be a frustrated professor.

 

...so much wrong on the net, and so little time to set them straight...

 

I try to stay away from the laptop after 11 or so, late-night light exposure and all that. If I'm still on afterward, my wife will frequently ask "Is someone wrong on the Internet?"

 

This comic is exactly what I thought of when @Kentucky posted, so glad you posted it. I think we all get to that some days, hopping from place to place to "correct" people, when so so many do not wish to be corrected, (or correct for that matter). Knowledge seems to be disdained nowadays, (and yes, that statement unfortunately applies to both political parties).

 

I've been told that ziplocs are good for coins. Anything you can put food inside of won't have chemicals bad for coins.

 

Counterexample: stomach.

Food storage has very different constraints from coin storage. Think of all the food you've eaten from brown paper bags.

 

Most of the modern flips don't contain pvc. The coin dealers I have been to all say bad things about pvc and they themselves sell coins in flips.

 

I also make sure to take all the air out of ziplocs, as much as humanly possible. There are some large bags of raw coins I've purchased from 2015 or earlier that look pretty much the same as they did when I got them. It helps as well if you double or triple your means of storage, like some of my ziplocs are inside of 50 caliber ammo cans.

 

Ziplocs aren't a bad choice, but they're pretty permeable -- their seal isn't perfect, and the plastic itself passes oxygen (and probably other gases/vapors). Double-bagging is better. Saran was the best choice for blocking oxygen, but it's no longer marketed to US/UK consumers. (You can still order it from Japan.) However, Saran is also a chlorine compound, so I'm not sure I'd want it in direct contact with a coin's surface. I've considered wrapping slabs in it.

 

Oh yes I also double bag. I'll put smaller into a larger bag and then stick it all into something else. So far none of my pre-Euro hoards haven't tarnished or discolored or at least not noticeably. Unsure of the differences between metals but I have thousands of .999 nickel coins that look the same here after years of storing.

 

Nickel is a special case; it's an active metal, but it forms a passivating oxide layer that protects it from a lot of things. (Same with aluminum, only more so.) Iron, on the other hand, gets the pox -- iron oxide tends to flake off, not offering much protection at all.

 

I guess it's not a coincidence that a great number of the iron/zinc I have from Europe look like they've seen much better days.

Most of the German 25 Pfennig coins (1918 I think?) I have come across have considerable surface damage.

 

Weeeeeeeeeeeell...Saran is polyvinylidene chloride, but is more stable than PVC (polyvinyl chloride). I bought some wrap in a Japanese grocery, but didn't see any bags.

 

I didn't want to correct anyone because I didn't understand the process that would facilitate that seemingly oxidation on bags of high quality/grade Mercury dimes, etc. coins, that I don't believe were ever near paper. I received them in cloth bags up to a half century ago where they were separated into $100 lots, closed in plastic food storage bags, housed in sealed steel ammunition cans. Many of the AU/BU grade condition coins were completely blackened when viewed up to a half century later.

I developed a proprietary non-dip, non-abrasive process for neutralization, but the coins are needed to be separated flat in a suspended labor intensive operation.

I don't believe there's a simple relatively non-destructive manner for neutralizing the "oxidated" covering. I just wanted to prove it could be done. I briefly, in the past, discussed the process in this venue. I didn't elaborate, as there are critical parameters that need to be met for successful uniform fields/devices conversion. I believe the average collector wouldn't have the patience for proper completion of surface conversion.

I showed completed lustrous specimens to a family member on a soft sheet, but he couldn't leave them in place, picking them up between his fingers. I gave some larger W.L. halves as presents in air-tites, but decided process disclosure was a futile exercise.

JMHO

 

What should I use to polish my First Spouse coins?

 

do you have the whole set?