En plein air

About

Plein-air painting is done outdoors, directly in front of the motif, rather than composed later in the studio. Earlier artists sketched outside but finished indoors. In the late 18th century Pierre-Henri de Valenciennes urged students to make rapid oil studies of sky and light outside, and John Constable painted clouds on Hampstead Heath in the early 1820s, noting weather and time on the back.

Two inventions made the practice easier: the collapsible metal paint tube, patented in 1841, and lightweight portable easels. Barbizon painters worked in the Forest of Fontainebleau, and Charles-François Daubigny fitted out a boat as a floating studio in 1857. The Impressionists made outdoor work central, and Claude Monet returned to motifs at different hours to catch changing light. Plein-air pictures often reveal their origin through quick, broken strokes, thin passages, simplified detail, bright daylight colour and, occasionally, grit or insects caught in the paint.