I have this old wall - over 200 years old. I began to remove old paint. There were about 4 to 5 layers of paint there. The problem is, I can't get the last layer of. It seems to be oil based and the wall surface is rough. This means - sanding wont help, simply scraping doesn't cut it and using a heatgun has almost no effect at all. Here's a picture of the wall.
This green bit is what I'm talking about. My question is - can I simply replaster it. Will it stay solid? Since the surface is rough, it should stick...right?