This article examines the differences between watercolour and gouache as painting materials, their common features and advantages, how they differ, when it is appropriate to use watercolour, and when to use gouache.
Schmincke Horadam Watercolour Paint Ultramarine Blue and Schmincke Horadam Gouache Paint Chromium Oxide Green
As a painting medium, watercolour has come into its own in the last few decades. It is no longer used mainly for preparatory sketches for large studio paintings and is now accepted as a serious medium for finished paintings. At the same time its nearest relative material, gouache, is still highly underrated both among artists and connoisseurs of painting. Lately a new trend has appeared: gouache has become more popular, both in terms of artists using this medium as their primary one, and in terms of the number of books and courses devoted to the specific properties of this material.
What is the Difference Between Watercolour and Gouache?
Speaking about these two materials, it is important to remember their main similarity and the main difference. These materials are similar in that they are water-soluble, but they differ in transparency. We will consider other specific similarities and differences, but this is the most important thing to understand.
Gouache differs from watercolour in its opacity: the binder in the paint is the same gum arabic that is used for watercolour, and there is usually also a higher pigment load, to add to the opacity. This is why gouache is opaque, dense and covering.
Watercolour as a material is more complicated in technique because of the transparency of the paint: layers are seen through each other, they are transparent and the previous layer is visible, so watercolour forgives less mistakes than gouache, which allows the possibility to add more layers in case of failures and mistakes.
Gouache is a favourite material of illustrators. Among the definite advantages of gouache, is the fact that it is a very convenient and compact material: it does not smell, there is no need for additional solvents, and occasional spots of paint can easily be washed away with water. The only real negative might be that you go through more paint with gouache compared to watercolour, because watercolour is commonly diluted with water to create washes, while gouache is often applied in a thicker, less diluted way, so you use more paint.
To better understand the difference in materials, I painted the same subject in watercolour and gouache using Schmincke Horadam Aquarelle Watercolour and Schmincke Horadam Gouache.
Painted with Schmincke Horadam Aquarelle Watercolour
Even the approach to painting in gouache and watercolour is different – someone aptly put it that opaque materials (oil, acrylic, gouache) are the experience of searching directly on the canvas, while watercolour is an expertise of concentration. In watercolour you need to think of the process and technology before applying the paint, in gouache you have enough time to decide while painting.
Painted with Schmincke Horadam Gouache
The sequence of applying layers in these materials is also different: the white colour in watercolour is traditionally the uncovered areas of paper. In this respect, gouache is more convenient: while the classic sequence of layers in watercolour is, for obvious reasons, “from light to dark”, gouache allows you to work in both ways: you can put light colour first and then dark, or vice versa, first dark and then light colour on top.
Gouache is more versatile, it allows you to make more textured strokes. Some may object that if you use watercolour too thick you can make paste-like strokes! But if you apply watercolour too thick (directly from a tube) it dries up in a thick glossy layer and you can really see it on paper. Gouache, on the other hand, allows you to put these dense strokes and it dries without this glossy sheen – but speaking of gouache, you should also remember that if you put too thick a layer of paint, it can later crack.
L – R: Schmincke Horadam Gouache Paint Chromium Oxide Green and Schmincke Horadam Watercolour Paint Chromium Oxide Green
In gouache it is difficult to achieve such interesting uniform transitions and smooth washes as in watercolour, and in general the paint is a little less plastic. You can blur layers with water or wash them with pure water, but it requires more accuracy and carefulness. Another important factor to consider is that gouache, when applied to the previous layer, snags the bottom layer, even on cotton paper, unlike watercolour, which on the corresponding paper allows applying layers without blurring the previous one.
Gouache is less demanding in everything – and that includes additional materials. With watercolour, the quality of paper and brushes are very important. But while watercolour paper works the best for painting in gouache, you can use any paper that isn’t warped by water.
Top to bottom:
Schmincke Horadam Gouache Paint Chromium Oxide Green
Schmincke Horadam Watercolour Paint Chromium Oxide Green
Schmincke Horadam Gouache Paint Ultramarine Blue
Schmincke Horadam Watercolour Paint Ultramarine Blue
Painting with watercolour requires relatively soft and controllable brushes, and sharp tips are critical, in gouache this is desirable – but not obligatory. One thing that is the same for both mediums, the quality of colours themselves are really important: student grade gouache differs from designer and professional as much as student grade watercolour differs from professional painters’ materials.
Top to bottom:
Schmincke Horadam Gouache Paint Chromium Oxide Green
Schmincke Horadam Watercolour Paint Chromium Oxide Green
Schmincke Horadam Gouache Paint Prussian Blue
Schmincke Horadam Watercolour Paint Prussian Blue
Gouache can be applied in a dense layer evenly and in such a way that you won’t see strokes of paint, which is also possible in watercolour, but requires more water.
Gouache dries faster than watercolour and is less likely to differ in tone and look paler after drying, as do most watercolour paints. The general rule of gouache is that after drying, dark tones appear lighter and light tones appear darker.
To summarise, these two materials are both made with gum arabic so are re-soluable, but the transparency of the watercolour and the opacity of the gouache require different painting techniques, have their own advantages, and have different final appearances.
L – R: Schmincke Horadam Gouache Paint Ultramarine Blue and Schmincke Horadam Watercolour Paint Ultramarine Blue
Watercolour requires more planning, because you cannot back up and correct mistakes. It requires more concentration and control over water, though this doesn’t mean it is always ‘tight’, it can be painted in a free, loose way, accepting the flow of water as a part of the process. And watercolour has its own special magic, that is very hard to express with words. It comes from the never quite controlled flow of paint, that you get only one chance to get it right, that the paint is a light film that seems to be a part of the surface, and of course the glow from the white paper shining through the transparent pigment.
Gouache is more suitable to contemporary painting where you work out the details as you go, with less planning. And it’s great for filling in flat areas of colour in illustrations or abstract paintings. It is more predictable and controllable, and in that sense it is much easier to use.
Further Reading
Underpainting in Oil and Acrylic
Art Terms Explained: Acrylic Painting
Inside the Sketchbook of Ann Witheridge
The History of Potter’s Pink (And Why It’s a Watercolourist’s Secret Weapon)
Shop Watercolour on jacksonsart.com
Shop Gouache on jacksonsart.com
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