Alla prima is a great way to work if you want a soft, painterly handling, but it can be a problem if you want to describe intricate details against a light sky, because the wet paint of the sky interferes with the dark strokes that you want to place on top.
Earlier painters generally didn’t work alla prima, at least not in the studio. Painters before the advent of Impressionism would typically paint a sky first, let it dry, and then paint the trees and other foreground elements over dry passages.
I have experimented with applying this idea to plein air painting and I can recommend it to you as an option. The tree study above was done in this way. It’s useful in situations where your chief interest is in the complex middle-ground tracery: road signs, telephone poles, sailing ships, trees, or intricate cloud formations.
The cloud study (detail, below) which I showed in an earlier post, was painted over a cloud-free sky panel.
Since clear skies are fairly standard and predictable, you can prepare a set of “sky panels” a few days in advance of an outdoor painting session. Cover the sky panel with a typical gradation of sky-colored pigments, and let it dry completely.
Later in the field you can rub the surface with a thin layer of oil painting medium to make it receptive. You can then paint the foreground details of trees or foliage without any danger of the sky color lifting up and mixing with the dark colors of the branches or leaves.
Tomorrow: L’Art Pompier