Editing En plein air (section)

== Equipment and challenges ==
[[File:Robert Antoine Pinchon, 1898, painting Le chemin, oil on canvas, 22 x 32 cm.jpg|thumb|left|[[Robert Antoine Pinchon]], 1898, painting ''Le chemin'', oil on canvas, 22 × 32 cm]]
It was during the mid-19th century that the "box easel", typically known as the "French box easel" or "[[Easel#field|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 (painting)|palette]] made it easier to go into the forest and up the hillsides.<ref>{{Cite web |title = Invention of box/ Field easel |url = http://artmovement.weebly.com/invention-of-box-field-easel.html |website = Realism & Impressionism |access-date = 2015-11-02}}</ref> Still made today, they remain a popular choice (even for home use) since they fold up to the size of a [[briefcase]] and thus are easy to store.<ref>{{cite web |url=https://www.pbs.org/pleinair/ |title=Plein Air |publisher=PBS |date=6 August 2007 |access-date=20 August 2010 |archive-date=22 August 2011 |archive-url=https://web.archive.org/web/20110822202637/http://www.pbs.org/pleinair/ |url-status=dead }}</ref>

The Pochade Box is a compact box that allows the artist to keep all 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.<ref>{{cite web| url = http://www.dickblick.com/pochade/boxes/| title = ''Pochade Boxes''}}</ref> These boxes have a rising popularity as while they are mainly used for ''plein air'' painting, they 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&nbsp;cm).<ref>{{cite web |title=Pochade box |url=http://www.artworkessentials.com |website=Artwork Essentials |access-date=29 December 2016}}</ref>

Challenges include the type of paint used to paint outdoors, animals, bugs, onlookers, and environmental conditions such as weather. [[Acrylic paint]] may harden and dry quickly in warm, sunny weather, and it cannot be reused. On the opposite side of the spectrum is the challenge of painting in moist or damp conditions with precipitation. The advent of ''plein air'' painting predated the invention of acrylics. The traditional and well-established method of painting ''en plein air'' incorporates the use of oil paint.