I am about to airbrush a large amount of area on my Fast Draw playfield with createx sky-blue opaque after I apply the first coat of 2pac. There are small areas with bare wood , that have been covered with 2pac and sanded smooth . Since sky-blue seems to be not covering so effectively like red or blue , I am considering putting a light coat of white on all the area to be painted , before airbrushing the sky-blue. Is that a common technique , and also is white a good choice , or a light coat of grey is more suitable for colors that do not cover so effectively.