Paint thinner isn't going to do too much. It's Lacquer thinner you want and can use on Porcelain. With Citri-strip, You spray it on and let it sit for 30-40 minutes and then wipe it off with rags and use a razor blade for the tough spots. Use the lacquer thinner to clean the sign off from the stripper residue. I wipe it down twice.

DOC @ THE AMERICAN GARAGE