Let's get this out of the way - applying masking fluid to a painting can be frustrating and difficult. I have a surplus of old brushes I can use (that I'm not afraid of ruining), but they never seem to be the correct size. In order to create the fine lines in the bottom-most orange slice, I was using a nail; the very fine, narrow sort of nail you would hang a picture with. This meant repeating the same action of dipping the nail into the masking fluid, dabbing it onto the paper to create a small line, pulling the dried excess fluid off of the nail, and going back for more. The ability to preserve the white of the page really makes the effort worthwhile!