Two cross-sections on paper. In watercolor a thin layer of blue pigment lets light pass through to the white paper and back. In gouache a thick, densely packed layer of blue pigment reflects the light at its surface, making it opaque and matte.

Concept · Paint and Its Surface

Watercolor and Gouache

Watercolor is pigment in gum arabic, thinned with water. Its glow comes from the white paper under the color.

Gouache carries more pigment for its gum, so it hides the paper.

  • Highlights are often bare paper, left unpainted.
  • Watercolor paper is usually coated with gelatin to control how fast it drinks in the wash.

See

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