Gold doesn’t tarnish. Titanium and aluminum tarnish to some extent, but the thin layer of corrosion resists further corrosion, or so I understand. What’s the best way to store silver and platinum bullion or coins that are prone to tarnish, inside or outside of a safe or safe deposit box?
I sold some platinum bullion this summer that was a little tarnished without too much problem: the vendor said they can easily melt it down and reform the stuff. Evaluation of that claim would also be appreciated. Maybe the ease varies by proximity to a major precious metal processing center. Or not.
I think the term is toning. It can be good or bad for rare coins. I also think it doesn’t matter for bullion coins, those with little-zero value over melt.
Don’t know but a light coating of BLO (Boiled Linseed Oil) will prevent iron and steel from rusting. It fills the pores in the metal and leaves a hard clear coating on the surface.
I’m pretty sure tarnish doesn’t affect the value of bullion coins, it would be the same as bars, etc. As you experienced, they will hold the coins and/ or sell off to an assayer or smelter anyway. Bullion is not the same market as collectible.
Saturating in oil will probably annoy some vendors/buyers.
AIUI Aluminum reacts to oxygen by forming crystaline aluminum oxide- sapphire. The thin coating of sapphire does indeed protect the rest of the aluminum.
I have no clue about platinum (and am unlikely to need answer about platinum in the forseeable future). I am very curious on how to prevent tarnish in silver. My Mom used to keep a stick of chalk in the case with our Passover utensils. She said it prevented tarnish.I suspect it was just a folk remedy that was of little if any help.
I realized I didn’t answer the question, in FQ. I think the best way to avoid tarnish (which is a reaction to oxygen and silver and its alloys) to silver is to store them in an airtight container or maybe one of those anti-tarnish silver wrap things used for silverware. It takes a while for silver to tarnish unless some sort of acids are present, which is in paper (I think) which is why you see some coins with edges tarnished but the centers pristine. I don’t know how airtight a safe deposit box is, but I wouldn’t worry about it with bullion coins.
Again, don’t oil them up (that’s fine for steel/iron things).
I think silver tarnishes by reacting with halogen ions, especially chloride ions, to form a black silver halide. This is actually the principle behind film photography.
If you make something to getter the chloride from a reasonably well sealed container, silver won’t tarnish in there. I think they sell paper impregnated with something to capture the chloride just for this purpose.
Also, poking around Google search returns, I can’t find any descriptions of how platinum meaningfully tarnishes or corrodes. My impression is that it’s almost as inert as gold.
They sell anti-tarnish cloth to line your box of silverware. We have some in the drawer where we store the silver and i think it works moderately well. It’s supposed to be more attractive to sulphur than the silver, so i suppose it wears out eventually, as it gets saturated with sulfur. But I’d think that just storing the silver air-tight would probably be good enough.