Do you mean no coins YOUNGER than 1970? Otherwise "Older than 1970" can't be LWC.
Not certain what your "contamination stains" are. The steel pennies in your photos are showing rust, which is caused from exposure to oxygen and moisture for a long period of time. Copper does not rust, however, it does corrode. Copper oxidation is a type of corrosion. Copper oxidation develops a verdigris colouration (blue-green).
How do you remove verdigris from coins? A product called VerdiCare (sometimes available from a CCF member BadThad) should help. Will acetone remove verdigris from coins? No, the damage is already done. Will acetone help protect your undamaged coins? Acetone is useful for removing any organic substance, so yes. It won't remove any pitting or damage from corrosion, but for protection of undamaged surfaces, yes, it should do the trick!
Not certain what your "contamination stains" are. The steel pennies in your photos are showing rust, which is caused from exposure to oxygen and moisture for a long period of time. Copper does not rust, however, it does corrode. Copper oxidation is a type of corrosion. Copper oxidation develops a verdigris colouration (blue-green).
How do you remove verdigris from coins? A product called VerdiCare (sometimes available from a CCF member BadThad) should help. Will acetone remove verdigris from coins? No, the damage is already done. Will acetone help protect your undamaged coins? Acetone is useful for removing any organic substance, so yes. It won't remove any pitting or damage from corrosion, but for protection of undamaged surfaces, yes, it should do the trick!






























