Notable lesson learned with this barn quilt: Never use an oil based polyurethane...it WILL yellow! Water based exterior poly only! I learned this the hard way! I used poly only because the aqua and the gray are interior latex "samples" from Lowes and needed protected. When using all exterior paints, I don't use poly, so this was a first for me. I originally used Spar Varnish, because I had some on hand. It made the nice brights look muddy. So I repainted the aqua and the gray, and found a water based exterior polyurethane to use instead. It turned out just fine!