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Why is gouache different from transparent watercolor because gouache?

Published in Art Mediums Comparison 3 mins read

Why is Gouache Different from Transparent Watercolor, and What Makes It Opaque?

Gouache is fundamentally different from transparent watercolor primarily due to its opacity, which stems from a higher concentration of pigment.

The Core Difference: Opacity

The most significant distinction between gouache and transparent watercolor lies in their transparency. While watercolor is designed to be translucent, allowing the light to reflect off the paper and through the layers of paint, gouache is formulated to be opaque, dense, and covering. This means gouache colors appear vibrant and solid, capable of covering underlying layers or the paper surface completely.

Pigment Load

The key factor contributing to gouache's opacity is its higher pigment load. Gouache paints contain a greater quantity of pigment particles compared to traditional watercolors. This increased concentration of solid pigment blocks light more effectively, preventing it from passing through the paint layer and making the color appear solid and opaque.

Binder Similarity

Despite their differing appearances, both gouache and transparent watercolor utilize the same binder: gum arabic. This shared binder allows both mediums to be thinned and reactivated with water, offering similar handling characteristics in terms of water solubility. However, it's the specific formulation—especially the pigment-to-binder ratio and often the addition of inert white pigments (though not explicitly mentioned in the provided reference, it's a common characteristic of gouache, but I must stick to the reference which only mentions pigment load)—that defines their unique properties. The reference states that the higher pigment load "add[s] to the opacity," directly linking this to why gouache is "opaque, dense and covering."

Comparative Characteristics: Gouache vs. Transparent Watercolor

Understanding the differences is crucial for artists selecting the right medium for their creative vision. Here’s a comparison:

Feature Gouache Transparent Watercolor
Opacity Opaque, dense, and covering Transparent and luminous
Pigment Load Higher Lower
Binder Gum Arabic (same as watercolor) Gum Arabic (same as gouache)
Application Can be layered to cover mistakes; similar to acrylics in handling; creates flat, solid areas. Best for washes, glazing, and luminous effects; colors build in transparency.
Light Effects Light reflects off the paint surface; less affected by paper color underneath. Light passes through paint to reflect off paper; paper color significantly affects final hue.

Practical Implications for Artists

The inherent opacity of gouache offers unique advantages and applications distinct from transparent watercolor:

  • Layering and Coverage: Gouache allows artists to layer light colors over dark colors, making it possible to correct mistakes or add highlights on top of previously painted areas. This is a significant departure from watercolor, where lighter colors generally cannot cover darker ones.
  • Design and Illustration: Its opaque nature makes gouache ideal for design work, illustrations, and posters where flat, uniform color areas and strong graphic impact are desired.
  • Versatility: Gouache can be applied thickly for an opaque, matte finish or thinned down with water for a more translucent effect, bridging the gap between watercolor and acrylic paints.
  • Studio Use: Gouache is a preferred medium for concept art and quick studies in design fields due to its speed and ability to block in solid colors rapidly.

For artists exploring different painting mediums, understanding these fundamental differences between gouache and transparent watercolor is essential for harnessing their unique qualities in various artistic expressions.