Unfortunately I haven't had the opportunity get instruction on this, but as an Art Director for some 25 years the concept makes total sense to me. Working on a Baltimore Ravens guitar for a friend and thought I would try it out. My question is to anyone who uses this Grisaille technique is: Do you or should you use a transparent base on the Createx C,M,Y illustration colors? I really don't want to over reduce them, but I also don't want to lay it on heavy to where you lose the underpainting. WIP shot below. Still working out the details and values. Thanks!