Here's a sketch that I did yesterday on a rainy day in Bennington, Vermont. I'm here as a judge for the exhibition of the Society of Animal Artists—more on that tomorrow.
Because of the rain, Jeanette and I had to find a painting spot that was under cover, so we drove around Bennington until we found this public building that wasn't in use on the weekend.
Working on watercolor paper, I did a very quick pencil layin, and then applied the "soup"—a thin layer of opaque titanium white, lowered just a little bit from pure white with a little blue, yellow, and red.
The soup went across the whole sky and the far end of the street, and then tapered off down past the treetops and toward the foreground. With 100% humidity, the soup took a while to dry so it influenced some of the mixtures as I laid on subsequent areas.
Here's what the palette looked like, with a mixed Schmincke and Rublev pan set of transparent watercolors, and gouache on the flanking areas in white, cad red, yellow, and ultra blue.
This idea of painting into a soup of gouache was used by William Trost Richards, and it's also a method you can use in oil using colored soup to influence your color schemes. Norman Rockwell and Andrew Loomis talk about this as an oil method. Just be careful to keep the soup thin, and only in areas where you want it to influence later mixtures.
Winsor & Newton Designers' Gouache Introductory Set each
Moleskine watercolor notebook
Caran D'Ache watercolor pencils
Amazon: Schmincke Watercolor Pocket Set,
and a larger Schmincke set for a better price that Steve suggested.
Super magnet for holding down the cup