Gouache vs watercolour vs acrylic: how the three water-based paints differ

Both are usually bound with gum arabic and stay soluble in water when dry, but gouache is opaque and covers the paper, while watercolour is transparent and lets the white of the paper give the light.

Schmincke, a German paint maker, defines gouache as an opaque watercolour and states that the two are fully compatible (Schmincke (opens in a new tab)). Winsor & Newton also calls them intermixable (Winsor & Newton (opens in a new tab)).

Watercolour is semi-transparent, so the white of the paper gives the washes a natural luminosity, and white areas are often simply left unpainted (Tate (opens in a new tab)). Gouache rests on the surface of the paper as a distinct layer (Canadian Conservation Institute (opens in a new tab)), and the Met describes it by its lack of translucency and its matte surface (The Met (opens in a new tab)).

Watercolour is painted from light to dark, because an opaque technique from dark to light is impossible in it (Schmincke (opens in a new tab)). Gouache lets you add highlights and light colours on top afterwards (Schmincke (opens in a new tab)).

Both re-wet after drying. Gum arabic is a resoluble binder, so watercolour can be lifted out or re-wetted (Golden (opens in a new tab)), and pigment can be removed partly or fully to reveal the white paper (The Met (opens in a new tab)).

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Gouache stays soluble in water after it dries, so it can be reworked but lifts when painted over. Acrylic dries water-resistant and flexible, so a dry layer stays put under the next one.

Acrylic paint is pigment dispersed in an acrylic polymer emulsion (Liquitex (opens in a new tab)). It is soluble in water while wet and dries fast, and once dry it is flexible and resistant to water (Getty (opens in a new tab)).

Traditional gum-based gouache is not water-resistant when dry, so it can move when painted over, smearing or bleeding (Liquitex (opens in a new tab)). A dry acrylic layer will not lift and muddy (Golden (opens in a new tab)).

Gouache dries matte (Getty (opens in a new tab)). Regular acrylics vary in sheen with the pigments used, and can be transparent or opaque (Liquitex (opens in a new tab)).

Gouache may crack if it goes on too thick (Winsor & Newton (opens in a new tab)), while acrylic can be applied in thicker layers (Golden (opens in a new tab)).

Acrylic looks lighter while wet and darker once dry (Golden (opens in a new tab)). Thin coats dry in 10 to 12 minutes, and thicker ones take longer (Liquitex (opens in a new tab)).

Paint makers disagree about mixing gouache with acrylic. Royal Talens says the two can be mixed without problems (Royal Talens (opens in a new tab)), Schmincke calls their compatibility poor (Schmincke (opens in a new tab)), and Winsor & Newton warns that some pigments may react with the acrylic, most likely pinks, violets and magentas (Winsor & Newton (opens in a new tab)).

Acrylic gouache is a gouache-like paint with an acrylic binder. It gives gouache’s flat, matte colour, but dries permanent and water-resistant, so it does not re-wet like traditional gouache.

Liquitex describes its Acrylic Gouache as a gouache paint with the extra benefits of an acrylic, made with a flexible acrylic binder, for a flat, matte effect and a permanent, water-resistant finish when dry (Liquitex (opens in a new tab)).

Gum arabic gouache can be re-wetted when dry, while Liquitex’s Acrylic Gouache will not re-wet once dry (Liquitex (opens in a new tab)).

Holbein says its Acrylic Gouache moves, blends and feels like traditional gum arabic gouache, is water-resistant once dry, does not shift in colour from wet to dry, and lacks the fragile surface of traditional gouache (Holbein (opens in a new tab)).

Watercolour is usually painted on sized watercolour paper; gouache on paper, card, board or absorbent primed canvas; acrylic sticks to almost any surface.

Watercolour is generally painted on paper treated with gelatin sizing, which makes it less absorbent (The Met (opens in a new tab)). Hot-pressed watercolour paper is the smoothest, for detailed work, and cold-pressed paper has a more textured surface, for effects such as granulation (Winsor & Newton (opens in a new tab)).

Schmincke recommends paper, cardboard, boards and absorbent primed canvas for gouache, and says grey or coloured grounds work for opaque gouache (Schmincke (opens in a new tab)).

Acrylics stick to almost any surface (Liquitex (opens in a new tab)).