toxicodendron radicansJul 19, 2020

Let's talk about bronze disease!

Bronze disease is a type of corrosion which can happen to any object made of bronze, or any other kind of copper containing alloy. It's irreversible and very difficult to stop. It's what causes old pennies to get that green fuzzy coating.

It's also not really a disease, but people used to think it was caused by bacteria.

Show threadtoxicodendron radicansJul 20, 2020

Bronze disease is a big headache for archeologists, historians, and museum curators. Bronze is an alloy made from copper and tin. It's one of the oldest alloys known to humans, and as a result, lots of ancient artefacts are made from bronze.

Because the corrosion is irreversible, it means a lot of ancient artefacts have been destroyed by bronze disease, and many more need to be carefully preserved to prevent damage.

Show thread^,,^ Oct 13, 2020
@InvaderXan Couldn't you stop it by adding sodium hydrogen carbonate (to convert the CuCl / CuClâ‚‚ to copper hydroxide), cleaning it with water (to remove salts) and then brushing off the remaining copper hydroxide?
Or dissolving the hydroxide with HCl and then cleaning it with lots of water (and maybe electropolishing it), since that's how PCBs are often made and they don't corrode either.
Show threadtoxicodendron radicans
@x44203 If it was that simple, historians and museum curators would not cite this as a major problem in the preservation of ancient artefacts.
Oct 13, 2020 at 8:55amWeb
Show thread^,,^ Oct 13, 2020
@InvaderXan Hm yes maybe there is other problems, like that there is now a rough hole and maybe the alloy used also reacts differently and gets porous or so (for example when the tin or zinc dissolves but the copper does not)...