Gouache - A heavy, opaque watercolor paint, sometimes called body color, producing a less wet-appearing and more strongly colored picture than ordinary watercolor.
What is Gouche?
Simply, a water-based paint, similar to watercolor but containing calcium carbonate (chalk) to make it flat and opaque.

Whats's Gouache?
Transparent watercolor is intended to be see-through. But watercolor has a close cousin that's meant to be opaque: gouache. This paint is formulated and milled in much the same way as transparent watercolor, with a gum arabic vehicle. It's designed, however, to lie down in an even, smooth layer. Brushstrokes level out, and the color is highly saturated and opaque through the use of added opacifiers. The very best, however, achieve their opacity through sheer pigment load. Gouache can also be used in tandem with transparent watercolor as a way to add punch and drama to the color range.

[Pictured above: Monsieur Boileau by Henri de Toulouse-Lautrec (1864-1901) Gouache on cardboard,
80 x 65 cm,
Cleveland Museum of Art.
We do not know who Monsieur Boileau was. The Gouache painting may be either the portrait of an individual, or of a general type. Both interpretations are possible. The image reveals both Lautrec's naturalistic penchant and his humor. The portly diner, possibly a businessman, looks both jolly and cunning. Keenly observed details, such as the man's way of holding his cane and cigarette, and his cross-eyed gaze, are characteristic of Lautrec's work. The picture also shows his mastery of subtle color. Click on image to enlarge.]

What is gouache?
Gouache is a heavy, opaque watercolor paint that produces a less wet-appearing and more strongly colored picture. Sometimes called body color, gouache is made like watercolor but has a gum Arabic added to it that makes the color go down in a more even, smooth layer with more saturated color.

Gouache Additives
What products or additives are sometimes added to gouache for effect?
There are additives that some artist use in conjunction to their gouache paints for effect. Ox Gall is a wetting. When dropped in water and applied to your paper with a wash brush will improve the paint's flow. Medium added to your gouache art supplies will improve paint adhesion and dries with a glossy finish. Masking fluid can be painted over an area that you want to keep free for color. Once dried, it peels right off, leaving the surface beneath it untouched.

Gouache Papers
What are cold press and hot press papers?
Most artists paint with gouache on paper. But the paper has to be heavier than ordinary sketch paper because it will absorb too much of the paint. Watercolor paper is recommended – either hot or cold press, which refers to the paper's finish. Cold press papers were pressed under cold rollers and have a grained texture. Hot press papers are made very smooth by their passing through hot rollers or very polished rollers. The very rough irregular, bumpy papers you sometimes see are not pressed at all.

The Shelf Life of Gouache
What is the shelf life of gouache?
If you are purchasing Gouache you should try to purchase it in tubes. Unlike acrylics that sometimes come in jars, gouache does not fare well in jars because of evaporation and separation. Gouache that comes In tubes has a long shelf life of 3-5 years. If you do happen to purchase Gouache in jars you should refrigerate it. Refrigeration slows down the evaporation and separation process.