I live in NYC in a building built in 1939. I decided to refinish 2 window sills and one radiator cover. I stripped the paint with a chemical stripper and quickly realized there was joint compound underneath the multiple paint layers.
Underneath that was rusted metal. Now this has turned into a bigger job than i thought. I need help figuring out what to do next and I have a basic plan, which is this:
use a wire brush or metal cup brush attached to a drill to get past all the joint compound and down to the metal. Sand the metal down. smooth out metal with Bondo filler. sand that down, use metal primer, then paint with an oil based rustoleum paint. I also bought a good mask in case there is lead paint in some of those old paint layers.