Using Homemade chalk paint to do two corner China cabinets. Recipe is 1/3 cups of plaster of Paris & water to 1 cup of paint. Doing gray with white interior on surfaces previously painted with semi gloss paint. Got a little white on the gray so wiped it off with a damp paper towel, and the gray paint wiped off too! I'm afraid to go any farther with painting! Do I need to stop and sand everything before going on or will the wax top coat seal it enough I won't have to be afraid to use the cabinets. I didn't sand to begin with because most articles I read said you didn't have to with chalk paint! Help!