Test paint permanence for yourself Gouache then, is a pigment, the powdered color, mixed with ingredients to make it smooth and adhere to the paper. Gum arabic is a common ingredient because it helps make the color more even and flow more smoothly. You can buy gum arabic to mix with any water based paints. Add a little bum arabic and distilled water to dried paints and mix until smooth and buttery. Don't add too much or the finished painting will have shiny spots, like varnish, where there is a build up of gum arabic.
Gouache is meant to be used more thickly than traditional watercolors.
The paint should be applied in a solid film of color for a gouache painting technique. If the paint is too thick, however, the resulting painting may crack off, especially if the colors have a high percentage of chalk. The colors can be thinned with water and made to soak into the paper, but this technique is most often used for underpainting. When painting, the light tints are made with a mixture of white and color and the whites are applied paint instead of the white of the paper. Artists choose to paint with gouache when they want to make paintings with solid areas of color or to paint elements one on top of the other.