Pile of coins covered in green powder, help!!

[bububoy]

captain that's a nice pushkalavati coin with the swastik, mit4396 !
luck you, i wonder what else did you discover in this hoard ?

@ Bruce, i need your advise, i live in a high humidity region and during summers the humidity is like 90%, i recently purchases a clean copper lot of some copper jitals, do i need to perform some cleaning etc ? what would you advise, i plan on using standard plastic 2x2 holders to preserve these coins.

mahe

[capnbirdseye]

captain that's a nice pushkalavati coin with the swastik, mit4396 !
luck you, i wonder what else did you discover in this hoard ?
mahe

Quite a few were beyond hope but I manged to salvage a fair number of assorted types, bronze disease had destroyed some & I've been keeping watch on the ones I saved as on one or two it reappeared but I just checked again & they seem stable for now

[Figleaf]

If a coin is clean, it doesn't need to be cleaned. IMO, the only reasons for cleaning are bad chemical processes that need to be stopped and crud blocking details.

By itself, humidity is not a problem. Condensation is the problem. Not sure what you mean by standard 2 x 2. If they are carton and stapled, they offer no protection against condensation. If they are carton and self-adhesive, they will in principle offer protection, but the glue can become undone. If they are of the airtite variety, you have complete protection against humidity in principle, but I don't believe anything never malfunctions. In all three cases, nothing is as good as inspecting your coins regularly.

The solution for condensation is two-fold. First, get the coins in an environment with a constant temperature. This can be a well-closing tin kept out of the sun, a ventilated vault or an air-conditioned room. Second, pack the coins with bags of moisture absorbers, desiccant packs that come with electric and electronic equipment. These packs do not have an unlimited capacity to absorb moisture, but their capacity can be renewed by heating them in an oven, which will evaporate the water they contain. You may be able to buy extra packs in electronics shops.

Peter

[bruce61813]

All the information is very sensible. In high humidity areas I would leave the coins in an open area for a month or so and watch for recurrence of any green spots.  The comment about condensation is very much to the point, but even atmospheric moisture is sometimes enough.  I am always checking my ancient bronze coins for possible outbreaks. Don't let coins with Bronze Disease come into contact with good coins, it will spread to the good coins. Also a good coat of REN Wax helps control the effects of moisture.

Bruce