The best white I had for this project was my pan of Japanese watercolors. My black paper didn't work very well so I used black watercolor on watercolor paper to create a black background. In the "triptych" (lol) the first image is posca and ink with gouache. The second image is all posca. The third image is all gouache. Gouache seems to work very differently than watercolor but with some practice I might get the hang of it.