What distinguishes gouache from other watercolors?

Gouache is distinct from other watercolors primarily because it is opaque, allowing it to cover the paper completely without showing its white surface. This characteristic enables artists to achieve rich, vibrant colors and strong contrasts that are not possible with traditional transparent watercolors, which typically allow the white of the paper to contribute to the overall luminosity of the work. The opacity of gouache means that layers can be applied without the underlying colors affecting the top layer, providing greater versatility in tone and color mixing.

Other types of watercolor, in contrast, are generally transparent and intended to be built up gradually in layers, allowing the artist to manipulate the luminosity and depth of color through the interaction of layers. This fundamental difference in opacity is what sets gouache apart in terms of technique and application, making it especially useful for specific styles of painting that require bold color applications and solid coverage.