Question about that green stain on Roman bronze coins I keep seeing

I was cleaning up some old coins a buddy brought back from a dig in Spain. One had this weird green crust I thought was just dirt, so I gave it a quick scrub with water and a soft brush. Turns out that green layer is actually a rare patina that holds the original surface details, and I basically wiped away a bunch of fine lettering. Has anyone else wrecked a coin by cleaning it the wrong way?

2 comments

2 Comments

karenw2326d ago

Same thing happened to me with a Trajan denarius. That green crust is called malachite patina, and it's basically a time capsule for the metal underneath. Water scrubbing strips it off like it's nothing. Now I only use distilled water for a quick soak if anything, and I never touch the surface with anything harder than a soft toothpick. Lemon juice or olive oil can work for stubborn dirt but you have to go slow and check every few minutes. For really valuable coins I just leave them alone now. The patina tells its own story and cleaning always does more harm than good in my experience.

andrew91626d ago

Wait I always thought scrubbing was the way to go, but after reading this I definitely messed up a few coins too.