Painting outdoors has a long history in the art world, but it was not until the early 19th century that it became widely practiced. Before this shift, many artists mixed their own paints using raw pigments. These pigments needed to be ground and mixed into paint, so portability was inconvenient. Most painting activities were strictly confined to the studio. Plein air paintings became a viable option for many artists once tubes of paint became widely available in the 1800s.