How To Slow The Degradation Of A Worsening Patina

a picture is worth 10,000 words...





I asked myself these questions and placed a $1 dessicant inside of a safe and waited for three months. The two shots here show how drastically the amount of water had accumulated inside of this dessicant while residing inside of a 'closed' safe.

Virtually every chemical reaction must have H2O to begin and come to an end.

The recommend Rh for coin storage is ideally about 30%. Anything lower is harder to achieve but not impossible.

IMO it is unnecessary to measure Rh unless you want to purchase more meters which can be avoided by simply observing and changing out the dessicant every couple of months or as needed.

Beautiful rainbow toning on a silver coin is delicate and unstable over the long term, and it's deterioration cannot be reversed -
much like feminine pulchtitude.

Unlike the feminine version, it can be however be almost be completely arrested by housing the coin in a completely air tight environment. A screw seal acrylic capsule of appropriate diameter would be the best solution to this problem.

Can't do that with the feminine version. She might have you arrested first!

Keep moisture away from coins. I simply put coins in Plastic Zip lock bags.

They do not. They are made with polyethylene. I would only use the clear ones though to avoid issues with dyes.

And to be clear, PVC is a rigid plastic. It is the softeners (plasticizers) added to it that cause problems for coins as it leaches out.

The other chemical to avoid is sulfur. Silver, in particular, reacts with sulfur-containing chemicals in the atmosphere to produce silver sulfide, which is black, and it does not need moisture in the air to form. This is what "tarnish" and "toning" on silver coins is made of. It is also why you get a "rotten eggs smell" when you clean tarnished silver coins with silver dip, as the silver sulfide reacts to form hydrogen sulfide gas.

Sulfur can be found in numerous everyday items. Virtually every kind of "rubber" has sulfur in it, because it's the sulfur cross-links that make a polymer "rubbery". Paper and cardboard, particularly if it's coloured, often has sulfur compounds in it (hence the oft-heard claims of Taco Bell napkins being good for "re-toning" silver coins). And of course sulfur could be in the air to begin with; ambient sulfur dioxide is less common nowadays with anti-acid-rain pollution control laws put in place way back in the 1980s, but if there's a kitchen in the house where garlic and other aromatic foods are being prepared, there'll be plenty of sulfur put up into the air from that source.

Sulfur will also cause coins of other metals to turn black - particularly copper and bronze.