Bronze Disease

[Pellinore]

Well, here are pics of the coins that I have given up, an Elymais tetradrachm and a 12 nummi from Alexandria, purported to be minted in 617-629 during the Persian occupation. The pics made from the side show that both coins have split and inside a squall of BD is forming, too.
-- Paul

[bruce61813]

I would not give up. Use the BD mix, in a heated solution, give it a scrub, at least every 72 hours.  change the solution after the scrub. The bright blue is safe, it is Azurite and related to Malachite. Both are stable, hard forms of copper oxide. The may be salts deeply embedded, I have seen this type of layering before. I had a coin split into 3 layers. None could come up with a definitive reason for it. Possibly the original plan had flaws.

Bruce

[pk72]

Hi. I require help.

    I realised yesterday that more than 100 of my copper/ bronze/ nickle coins have turned absolutely BLACK or are DISINTEGRATING AT THE EDGES. Even bimetallic coins with golden rims have now black rims eg Russian bimattelic coins. These were perfect brown/ golden a few months back. They had been stored in a coin album in plastic pockets in a damp place by mistake (there are traces of moisture in the plastic sheets also). Maybe the monsoon weather in India has accelerated the deterioration process.

   What has been discussed above is for old/ ancient coins. But mine are modern coins from 1870 - 2011.
   
   How do I clean these? (I am changing the stowage space).

  Thanx in advance.

[Figleaf]

The monsoon is the second worst enemy of coins - the first is artificial fertiliser. Do you live close to the sea? Salty air and hard wind combined with moisture are pretty bad also. I hear that if there is no better solution, a tin can that is difficult to open (closing well) is a good place to protect coins from moisture during the monsoon season. While it is possible that the plastic was bad, it is not so likely. Plastic softener will produce a grey deposit on coins, usually over a period of a few years. The moisture inside points at the monsoon. Modern coins are quite sensitive to moisture and very hard to restore, but the late 19th century coins may still be salvageable.

If Bruce doesn't come in here in the next few days, I suggest you send him a PM.

Peter

[pk72]

Thanx Peter

[bruce61813]

Hi. I require help.

    I realised yesterday that more than 100 of my copper/ bronze/ nickle coins have turned absolutely BLACK or are DISINTEGRATING AT THE EDGES. Even bi-metallic coins with golden rims have now black rims eg Russian bimattelic coins. These were perfect brown/ golden a few months back. They had been stored in a coin album in plastic pockets in a damp place by mistake (there are traces of moisture in the plastic sheets also). Maybe the monsoon weather in India has accelerated the deterioration process.

   What has been discussed above is for old/ ancient coins. But mine are modern coins from 1870 - 2011.
   
   How do I clean these? (I am changing the stowage space).

  Thanx in advance.

I apologize for not having been around much. Do as Peter does and PM me! I am not too experienced with nickel-based coins, but it sounds like a reaction with vinyl (PVC) materials. I would try a bath and scrub with acetone, or fingernail polish remover. Then scrub in soapy water. If you haven't already done this, look for Mylar holders, they are stiffer but don't react with the metals.

Bruce