I use 4 ply acid free white matt for my B+W prints with the same for overmatt. I prefer black metal frames for white walls and silver metal for neutral walls. I also like a lot of matt around my photos. I put 8x10 prints on 14x18 matt, 11x14 prints on 16x20 matt and 16x20 prints on 24x28 inch matt. But this is just how I like it. You can use all purple if tht flips your switch. Have fun !