Redoing a room and the radiator had a lot of old paint, including emulsion I think, so I took it to a local place and had it shot/sand blasted to remove the paint. It's come back with a slightly rough finish, like fine sand paper. Do I need it to be smooth before painting? Was just going to use rattle can radiator paint. Will it be smooth after several coats of that? The paint is suitable for bare metal, so wasn't planning on priming or anything. Thank in advance!