I have seen this used on silver, but...had a bunch of lead and brass and some iron from the Virginia red dirt. Was feeling lazy and didn't want to hand brush each piece. So I took a small bowl and put some regular hydrogen peroxide in it and microwaved it 1 minute and a half. I stuck the items in the hot liquid and left them about 5 minutes. Almost all of the red dirt was gone and the patina was still intact on everything. Remember to NOT put the metal items in the microwave, but we all knew that.