Patt:
I learned the verdaccio method from Frank Covino. This underpainting method primarily concerns value and creating a monochromatic underpainting upon which you will impose color.
I use Mars Black, Flake White, and Chromium Oxide Green to make nine values of a gray-green color. In the past, I have painted it over a minutely detailed charcoal rendering, however, you could easily paint with verdaccio over a white or toned ground. You are actually rendering the form in the verdaccio values - I have several examples of it on my website.
Hope that helps and thanks for your kind words about my work!