I have done quiet abit of fabric painting, But I've never done it on a finished item. I do mine piece by piece. I use acrylics with a textile medium, I paint or shade the picture, or said design, then create the quilt top. I'm not saying you could'nt do it. However I would suggest working with the paint on scrap pieces to check your control and brush technique. Then make your decision. I'd hate for you to mess up your quilt.