I've started scraping the paint from my kitchen window sill -- which brought up the last layer very easily just using a razor-blade scraper with a handle - obviously a latex, and I suspect about 10 years old. Now I have a layer that looks like the original -- maybe from about 1974 or so. It is sort of crackled in some places. Do I sand it off? Do I strip it with something -- if so, what? I intend to repaint it with a glossy white latex paint.