(hint #1) Being able to play whatever I want has been a central theme to my own discovering how to play guitar. I've been on that path for 37 years, and it's enabled me to uncover, test and refine a unique, skill generating learning approach.
It is important to note that urethane foam is most commonly used to refer to a material made from polyurethane. The urethane reference in this name is to the type of links, also known as carbamates, that join the units in polyurethane.
It is common practice to follow a base-coat urethane with a clear coat, however some clear coats tint the color, especially if it is black or white. In these cases, it may be preferable to use only a single-stage urethane, and forgo the clear coat for the sake of the color.