What Is Gouache? How It Differs from Watercolour and Acrylic

Gouache belongs to the same family as watercolour: pigment bound in gum arabic, thinned with water, applied to paper. One difference changes its entire character. Gouache carries a higher pigment load and a chalk-like white filler. That filler stops light from reaching the paper, which makes the paint opaque.

The result is the reverse of watercolour logic. In watercolour, light tones come from the white of the paper and are made by leaving it bare. In gouache, light tones are painted, laid over darks. The painter can go backwards.

How the surface looks#

Gouache has a finish of its own: completely matt, velvety, flat. It has neither the depth of oil nor the plastic sheen of acrylic. That matt quality is why it was the standard for posters, illustration and animation backgrounds for decades; because the surface does not reflect, colour reproduces faithfully in photographs and in print.

The same matt quality means a work dries lighter than it looked while wet. A dark tone fades a step as it dries, a light tone deepens slightly. Experienced gouache painters judge colour not by what is on the paper but by what it will become.

It re-dissolves when dry#

This is its defining trait. Gum arabic stays water soluble, so a dry layer of gouache softens again the moment it is wetted.

That is both a tool and a trap:

• You can reopen a dry passage with a damp brush and soften a transition.
• Layering over it, if you scrub, lifts the layer below and muddies both colours. Upper layers must go on with less water, in a single stroke.
• A finished work is defenceless against water and high humidity. One drop leaves a permanent mark.

Acrylic gouache parts ways here. It looks the same, matt and opaque, but its binder is acrylic resin and it becomes insoluble once dry. It is the right choice for building many layers, or for work that must not fear moisture. What you give up is the ability to reopen a dry surface.

How it differs from acrylic#

Acrylic is also opaque and thinned with water, which is why the two get confused. The distinction is clear in three places:

• Finish: acrylic dries to a slightly glossy plastic film, gouache is fully matt.
• Reversibility: acrylic is permanent once dry, traditional gouache always re-dissolves.
• Support: acrylic works on canvas, wood and walls; gouache is essentially a paper paint and cracks on stretched canvas because thick layers form an inflexible film.

Paper for gouache#

Watercolour paper is the right ground for gouache too. Not going below 300 gsm is a practical rule; gouache asks for less water than watercolour, but paper still saturates once layers accumulate.

Texture depends on the work. The light tooth of cold press paper makes it easier to cover broad areas evenly. Hot press is smooth and preferred for illustration that needs fine lines and crisp edges.

Caring for a gouache work#

Water solubility makes framing a gouache non-negotiable.

• Frame it behind glass or UV-filtering acrylic. Left open, a gouache suffers from humidity and from being touched.
• Paper and glass must not touch. A mount sits between them; in damp air, paper stuck to glass is stained permanently.
• Use acid-free mounts and backing board. Acidic card yellows the sheet from the edges over the years.
• Do not hang it in bathrooms, kitchens or on exterior walls.
• Avoid walls in direct sun, since some gouache pigments fade faster in light than watercolour does.

Which one for which job#

Choose watercolour for transparency, light coming through from the paper and fluid transitions. Choose gouache for flat, saturated fields of colour, crisp edges and the freedom to correct. Choose acrylic or acrylic gouache when you need permanence or a support other than paper.

Works on paper in the Peck Art Studio collection are listed with their technique, because care requirements follow from it. If you want to know which paint and paper went into a piece you like, check the materials on its page or simply ask us.