01-08-2004, 10:12 AM
Hi Robert,
I head about the egg trick quite some time ago, but had forgotten about it. The way it works is that an egg produces a sulphur compound, H2S, also known to the rest of us mere mortals as rotten egg smell (remember Chemistry 101? That's a classic).
Although not a chemistry specialist at all, I remember learning that sulphur is highly reactive with silver, and gives an irridescent, rainbow-like patina, usually quite attractive; IMHO, I can't understand why anyone would want to use that black, oily fake patina when it is so simple and fairly fast to "manufacture" real patina.
Silver is not the most reactive metal there is, on the contrary. From the top of my head, so please do not hold it against me if I make some minor mistake, from most reactive to least reactive metal most commonly used for coin and medal making, we have:
. tin
. aluminum
. iron
. copper
. silver
. platinum
. gold
A common practice in numismatics is to coat coins with a very thin layer of clear lacquer. As an example, all coins from King Farrouk's collection were so coated to protect them from the Egyptian ambiant humidity and the reactivity of the metal they were coined in.
I am sure that someone more knowledgeable than I can provide further details to benefit us all.
Marc
I head about the egg trick quite some time ago, but had forgotten about it. The way it works is that an egg produces a sulphur compound, H2S, also known to the rest of us mere mortals as rotten egg smell (remember Chemistry 101? That's a classic).
Although not a chemistry specialist at all, I remember learning that sulphur is highly reactive with silver, and gives an irridescent, rainbow-like patina, usually quite attractive; IMHO, I can't understand why anyone would want to use that black, oily fake patina when it is so simple and fairly fast to "manufacture" real patina.
Silver is not the most reactive metal there is, on the contrary. From the top of my head, so please do not hold it against me if I make some minor mistake, from most reactive to least reactive metal most commonly used for coin and medal making, we have:
. tin
. aluminum
. iron
. copper
. silver
. platinum
. gold
A common practice in numismatics is to coat coins with a very thin layer of clear lacquer. As an example, all coins from King Farrouk's collection were so coated to protect them from the Egyptian ambiant humidity and the reactivity of the metal they were coined in.
I am sure that someone more knowledgeable than I can provide further details to benefit us all.
Marc
Robert Pierce Wrote:Ed,
Until reading this thread I had little concern about the environment in which we cased/displayed our medals, etc. Nothing like the comfort of ignorance. After reading into it, I can now understand the necessity. Years ago a fella told me that if you came across a piece, let's say, a 1939 Iron Cross (EK1 for those of us who collect such) that had been cleaned by the previous owner, and you wanted to reapply the patina to the silver of the cross, you simply put it in a bowl with a cracked hard-boiled egg and cover it, you would surely see the patina reform on the silver after a 'season'. Sounds like a strange recipe, but the point is, there is no doubt that some agent (chemical) in the egg produces rapid changes on the parent silver. Some of you may know what this agent is that does this; I haven't a clue. I heard from another person that humidity really speeds up this process on silver as well. Sooo, it sounds like there are quite a few other hazards to consider. And, as another member stated, there are neutralizers which can be added to the environment to slow down or hopefully stop this ageing process.
It seems there's more to consider than just the expense $$$ of our hobby. And all the while the original recipient didn't give one thought toward all of this. He was just happy to have survived it, and show that he had.
Respects.
Robert
