Distinguishing Watercolor and Gouache: What's the Difference?

Watercolor and gouache may look similar at first glance—they both come in tubes, are water-based, and are often used on paper. But if you're an artist, collector, or buyer of antique works, knowing how to tell the difference between the two can be crucial. In this guide, we’ll explore the key distinctions between watercolor and gouache—visually, technically, and historically.

What Is Watercolor?

Watercolor is a transparent paint made with pigments suspended in a water-soluble binder (usually gum arabic). It’s known for its luminosity, delicacy, and the ability to build transparent layers (known as glazing).

Characteristics of Watercolor:

• Transparency: Light passes through the paint and reflects off the paper, giving it a glowing effect.

• Soft edges and washes: Often used in landscapes, portraits, and studies.

• Lightweight texture: The paper shows through the paint.

• Layering: Colors are built up gradually using thin washes.

• Limited correction: Mistakes are harder to hide or fix.

What Is Gouache?

Gouache (pronounced gwash) is similar to watercolor but with added chalk or white pigment, making it opaque and matte. It is sometimes referred to as "opaque watercolor."

Characteristics of Gouache:

• Opacity: Light doesn’t pass through the paint; colors appear solid and matte.

• Vivid pigments: Stronger coverage than watercolor.

• More forgiving: You can paint light over dark and rework areas.

• Velvety finish: Often used in design, illustration, and poster work.

• Used by masters: From 18th-century French decorative artists to modern illustrators.

Side-by-Side Comparison

Feature	Watercolor	Gouache
Transparency	Transparent	Opaque
Light reflection	Through paint to paper	Surface reflection (matte)
Color layering	Light over white	Light or dark over any base
Texture/finish	Smooth and light	Dense and matte
Corrections	Difficult to rework	Easy to modify or layer
Use cases	Landscapes, botanical art	Posters, illustrations, decorative art

How to Tell Them Apart in Antique Artworks

When analyzing antique or vintage works on paper:

• Look at the light: Watercolors often glow with depth; gouache looks flatter and more pigmented.

• Check highlights: If white is painted on top rather than left blank, gouache may be used.

• Texture: Gouache can crack or show brushstrokes if thickly applied; watercolor rarely does.

• Paper type: Watercolor paper is often more textured; gouache may be used on smoother surfaces too.

Collectors and conservators often use magnification and light tests to confirm the medium.

Which One Should You Use?

• Choose watercolor if you want softness, subtlety, and luminous layering.

• Choose gouache if you want bold colors, solid shapes, and the ability to revise your work.

Both are valuable mediums with rich artistic traditions. Some artists even combine them, using watercolor for washes and gouache for details.

Final Thoughts

Whether you're evaluating a 19th-century painting or choosing the right medium for your next creative project, understanding the difference between watercolor and gouache helps you appreciate the intention behind the art. In antique artwork especially, this distinction can affect both valuation and authenticity.