When I hang an old metal clock on the wall, the metal acts almost like a pencil and leaves gray lines or scuff marks all over the paint. These lines won't easily clean off, either. What in the world causes this? Even if I put Scotch tape over the metal that contacts the wall it still does this. I've noticed that other metals will do this to paint, like coins. Is the metal shedding a layer onto the paint? Or is the paint reacting somehow to the metal, which occurs even through a layer of Scotch tape? I've searched all over the internet but couldn't find a discussion of this phenomenon.
- posted
17 years ago