Plein aire

En plein air (French pronunciation: ​[ɑ̃ plɛn ɛːʁ], French for outdoors, or plein air painting) is the act of painting outdoors. This method contrasts with studio painting or academic rules that might create a predetermined look.

Artists have long painted outdoors, but in the mid-19th century, working in natural light became particularly important to the Barbizon school, Hudson River School, and Impressionists. The Newlyn School in England is considered another major proponent of the technique in the latter 19th century. The popularity of painting en plein air increased in the 1840s with the introduction of paints in tubes (like those for toothpaste). Previously, painters made their own paints by grinding and mixing dry pigment powders with linseed oil.

The act of outdoor painting from observation has been continually popular well into the 21st century.

It was during the mid-19th century that the box easel, typically known as the French box easel or field easel, was invented. It is uncertain who developed it, but these highly portable easels with telescopic legs and built-in paint box and palette made it easier to go into the forest and up the hillsides. Still made today, they remain a popular choice (even for home use) since they fold up to the size of a brief case and thus are easy to store.

The Pochade Box is a compact box that allows the artist to keep all of their supplies and palette within the box and have the work on the inside of the lid. Some designs allow for a larger canvas which can be held by clamps built into the lid. There are designs which can also hold a few wet painting canvases or panels within the lid. These boxes have a rising popularity as while they are mainly used for plein air painting, can also be used in the studio, home, or classroom. Since pochade boxes are mainly used for painting on location, the canvas or work surface may be small, usually not more than 20 inches (50 cm).

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Wikipedia