Trost Richards Plein Air Watercolors

The Brooklyn Museum has a good collection of sketchbooks and watercolors by William Trost Richards which give insight into his practice of painting studies on location.

 William Trost Richards (1833-1905) "Landscape with Tree"

This partly finished study is 10 x 14 inches. (25.4 x 35.6 cm) on smooth beige paper. It's mostly and transparent watercolor with some opaque touches in gouache. He used gouache for the thin twigs on the far left, but he carefully painted around the illuminated leaves in the center of the picture. 

In this case, his initial steps don't include a very detailed pencil drawing. The unfinished area of the fence shows a few light washes and some locator lines painted with a brush in watercolor.

William Trost Richards, American, 1833-1905, Rhode Island Coast: Conanicut Island ca. 1880

This study is the same size, carried through to finish. It uses a similar method: painting large shapes rather loosely (but accurately) with larger brushes, and then subdividing those masses into smaller textures and details.

Although this method requires large reserves of patience and concentration, I don't think it would necessarily take too long; I believe a painting like this could be done in an afternoon or perhaps two consecutive sessions.

William Trost Richards, American, 1833-1905 at the Brooklyn Museum