I took a B&W photo tinting class a few years ago and we used the paints with the swab technique as well. I bought the "Marshall's Photo Coloring System Oils" as well as a can of "Marshall's Pre-Color Spray" Of course they are still sitting on my shelf never opened, but reading the directions inside it says "glossy prints, polaroid prints, glossy snapshots, newspaper and magazine pictures can be colored if first given a coating of Marshall's Pre-Color Spray" It doesn't say anything about sepia tone pictures, the only thing is says is to instruct your photo finisher to use matte paper, not glossy. I found these products at Michael's. I'd sure hate to ruin an expensive photo, but it kind of sounds like as long as it has a matte finish the oils work.