The Difference Between Watercolor and Gouache Paints

Watercolor, gansai, gouache, and poster color paints have a lot of similarities, but they’re not exactly the same. Keep reading for a detailed look at the differences between these versatile water-soluble paints.

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What is the Difference between Watercolor and Gouache? Watercolor is transparent and gouache is not. Otherwise, they’re pretty similar! We’ll sum up the differences here and get into detail below.

Watercolor Gouache

Transparent Finely-ground pigments Creates light colors through preserving the white of the page Difficult to lift from the page All colors appear lighter when dry Looks delicate and ethereal

Opaque Larger pigments Creates light colors with opaque light paint Easy to lift from the page Light colors dry darker, dark colors dry lighter Looks solid and crisp

What Are the Ingredients in Water-Soluble Paint? Pigments

Small pigment particles sink further into the paper. Large pigment particles sit on top of the paper. Watercolors, gouache, and poster colors all rely on pigments for their coloring rather than dyes. This means that tiny pieces of colored stone or other physical materials are suspended in the paint mixture, rather than being dissolved like dye. The most consistent difference between these paints is the size of their pigment particles. The smallest pigment particles are in western-style watercolors, followed by Japanese gansai watercolors and gouache particles. Poster colors have the largest pigment particles. Generally speaking, small pigment particles make paint that’s more transparent and harder to lift from the paper. They’re also less likely to form granulation effects. This is because the lightweight pigments spread more evenly over the paper. Bigger, heavier pigments tend to settle into the texture of the paper and may have visible darker spots or “grains” of color. Some pigments contain toxic chemicals like cadmium and cobalt.

However these chemicals are coated in binder during the paint-making process, so they’re no longer water soluble. This greatly limits health risks. That said, they’re still fat soluble, so don’t put them in your mouth! To be extra careful, you can let paint water fully evaporate and dispose of it into a trash can instead of pouring it back down the pipes. Binder All paint uses a binder to hold the ingredients of the paint together. Many watercolors, gouache, and some poster colors use gum arabic (the dried sap of the acacia tree) as their binders. Gum arabic easily redissolves in water after it dries, so it’s easy to reactivate paint made with it for blending and lifting. Japanese gansai watercolors traditionally use animal glues as binders, but many modern gansai paints use alternatives like beeswax and sugar. These binders can give gansai a glossier finish than Western watercolors, but they otherwise behave quite similarly. Additives Water-soluble paints also contain additives, which vary considerably between product lines and even between individual paints in the same line. Some common additives are humectants to keep the paint moist, preservatives to prevent mold, brighteners to make the paint more vibrant, and dispersants to help the pigment spread out in water. Other additives “stretch” the paint so that it contains less pigment. This can make the paints less expensive or tone down intense pigments so that they are easier to use with other paints in the same product line. Although some additives are necessary, they can have side effects. Paints with brighteners look more colorful in the pan and when wet, but they’re typically more opaque and develop a faded or chalky appearance when dry. Paints with dispersants or large amounts of humectants can penetrate more deeply into the paper fibers and resist lifting. Not all manufacturers list what additives they use, but artist-quality paints usually have more pigments than additives when compared to student-grade paints.

Paint Considerations Transparency and Opacity Transparent and opaque paints.

Opacity and transparency refer to how thoroughly a paint covers the color underneath it or allows it to show through, respectively. Broadly speaking, paints with smaller pigments are more transparent and paints with larger pigments are more opaque. This is because the same number of pigment particles in a unit of paint will be more spread out if the particles are small, leaving more space for the paper to show through. Larger particles take up more space, so they block more of the paper. Additives like brighteners and white pigments can also make paint more opaque.

Blendability Good blending versus muddy blending. All of these paints are easy to mix in a palette or on paper. They can also reactivate with water for blending edges together. However, hues that are made with a mix of different pigments can get muddy when blended with other colors. Poster colors are often made with multiple pigments, but so are some watercolors and gouaches. Be sure to test paints on a piece of scratch paper to see how well they blend if you’re not sure whether they’re made with single pigments or not. If they don’t blend well, use thicker layers of paint to reduce the chances of the underlying color reactivating and blending with the new color.

Another factor to keep in mind is color temperature: a “cold” or bluish yellow might be a pure pigment, but when mixed with red, it won’t make the vibrant orange that a “warm” yellow would. For a little more information on color mixing, check our guide to the best watercolor supplies. Lifting Slight lifting versus significant lifting. Artists often lighten paint that’s already on the paper by dabbing it with water and a dry brush. This technique is called “lifting.” If you’re not careful, it can sometimes happen accidentally! Paints made with smaller pigments, like watercolors, tend to be harder to lift because the particles can nestle snugly between paper fibers. Larger particles don’t fit between paper fibers as well, so they’re more likely to sit on the surface of the paper, making lifting easier.

Surface Watercolors, gouache, and poster colors all work well with watercolor paper, which is specifically designed to stand up to the amount of water used with these paints. Gansai watercolors are made for use with traditional Japanese washi paper but can also be used on watercolor paper. Both gouache and poster colors are opaque enough to be used on colored paper. Metallic watercolors also look striking on contrasting paper.

Watercolor paint is known for its transparency, which allows it to create delicate washes and nuanced, layered shading. Its transparency comes from its finely ground pigments. The small particles spread evenly over the paper to make smooth washes and allow the color of the surface below to show between each particle. Although the transparency of watercolor can result in beautifully luminous artwork, it also limits how these paints can be used. Light colors are not opaque enough to cover previous layers, so they must be applied before dark colors and then carefully avoided for the rest of the painting. You may be able to lighten dark areas with lifting if you accidentally put down a dark color too early, but no guarantees! You can also cover areas that need to stay light with masking fluid to protect them from stray paint. Be aware that watercolor tends to look lighter when dry than when wet. We recommend creating a swatch sheet of all of your paints, so you have visual references for how they dry. If you’re painting quickly, don’t be afraid to put down bold, bright colors. Some watercolors are less transparent than others. Certain pigments, especially earth minerals like cadmium red and yellow ochre, naturally make more opaque paints. Other paints are made more opaque with additives. Both these and gouache are sometimes referred to as opaque watercolors, but gouache is made with larger pigments.

Gansai are traditional Japanese watercolor paints. Gansai are slightly more opaque than Western watercolors. Gansai is a traditional Japanese watercolor.

It’s designed to be used in a single layer on absorbent washi paper rather than in multiple layers, but it can still be used that way. It’s made with larger pigments than Western watercolors. This makes it both more opaque and easier to lift, as the larger pigments block more of the paper and don’t penetrate as far into the surface. It also tends to be made with more intense pigments for extra vibrancy. When used for washes, it often creates interesting granulation effects with a textured or mottled look. Traditionally, gansai is bound with animal glue. However, modern gansai can be made with beeswax, sugar, and other binders. This can give gansai a glossier finish than Western watercolors, especially in areas where they were applied heavily. Kuretake Gansai Tambi Watercolors are made with water-soluble resin.

Gouache is made with intense concentrations of large pigments. Gouache is mostly opaque and dries to a flat finish. Gouache is very similar to watercolor paint in its composition. However, it’s designed to be opaque and dries to a flat finish. It’s made with intense concentrations of large pigments. Many gouaches use additives like chalk and titanium dioxide (known as titanium white when it’s made into a paint) to make them more opaque. Others, like M. Graham Artists’ Gouache, do not. Avoiding additives means that some colors remain semi-transparent, but it also keeps them more pure. This allows artists to choose whether to mix colors with titanium white to achieve full opacity or work with them as is. Gouache’s opacity gives you more freedom to paint on colored papers and add light colors over darker hues. Its flat finish makes it good for solid shapes that don’t show the pooling and gradation common to watercolors. Gouache can be diluted like watercolor paint if you don’t need its full opacity, but its washes aren’t as delicate. Gouache also lifts easily due to its larger pigments. If underlying colors reactivate and mix with layers you add over them, layer with thicker paint to reduce the chance of accidental lifting. Unlike watercolor, light-colored gouache dries darker and dark gouache shades dry lighter.