Has anyone taken a thrift store canvas painting, unframed, and just primed it and painted something? I got a hideous painting and I was thinking of either collaging over it or painting over it. I could smooth out some of the more protruding paint lumps with a little sandpaper, and just prime over it then paint. It's just one of those canvases pre-stretched that are expensive at Michaels. It's a Fredrix 18"x24"... I quoted some online around $17 and I totally got this one for $2.50.