When finishing with 600 grit, fine scratches remain that retain paint. Try grits towards 2000, the more polished the piece is, the easier it is to remove the paint. I also experienced this thing. Success!
Hello! I am new to the forum. I have done all the sculpting techniques in all materials for several years. About thirty years ago I engraved knives with a chisel and a hammer, without knowing what it was about. I notice that I sharpened the chisels well. I made the drawing directly with the...