We recently bought an old house circa 1908. Most of the renovations are going well but we have hit a problem with the stairs. There was this very odd shiny grey paint on them. Someone had painted over it with latex and it was coming away in sheets. They had used the same paint on some of the moldings and while additional layers had difficulty sticking it wasn't nearly as problematic. We thought originally that this paint may have been oil based, but now we are wondering if it isn't some older formulation.

We tried removing it with paint stripper and it ignored it. The pain stripper soaked into the paint covered wood and did literally nothing.

We would like to get as much of the paint off the stairs as we can. Right now we are sanding, but that too is far less effective than hoped as well. Any chemistry suggestions?