Understanding the Differences Between Watercolour and Gouache Painting

Palettes rich with colors and techniques, watercolour and gouache are both beloved by artists for their unique characteristics and expressive potential. While both are water-based, holding a striking resemblance in their applications, they diverge significantly in terms of their opacity, handling, and overall aesthetics. This article delves into the key differences between these two mediums, offering insights for artists and art enthusiasts alike.

Introduction to Watercolour and Gouache

Watercolour and gouache are both water-based painting mediums that require activation with water. However, gouache occupies a fascinating middle ground, often described as a hybrid between watercolour and acrylics. This blend allows for a unique range of effects, from transparent washes reminiscent of watercolour to opaque and bold applications akin to acrylics or oils. One of the defining traits of gouache is its opacity, which allows for painting from dark to light without compromising the underlying layers.

The Opacity Factor

One of the most striking differences between watercolour and gouache lies in their opacity. When a layer of watercolour is applied, the white of the paper and any preliminary drawings underneath become visible. In contrast, gouache is more opaque, meaning the paper will not show through nearly as much. This makes gouache ideal for creating solid, non-porous surfaces, often mimicking the look of acrylic or oil paintings. Such opacity also allows for rich, deep color layers that can be built up without the need for additional mediums or techniques.

Water Solubility and Cleanup

Both watercolour and gouache are water-soluble, meaning they remain alterable for longer periods. However, the degree of water solubility differs. Watercolour pigments are translucent, boasting the characteristic of allowing the white of the paper to glow through them. Gouache, on the other hand, is highly opaque, with added ground chalk or calcium carbonate to block light reflecting through to the substrate. For this reason, gouache requires a more meticulous approach, as significant color will wash away upon contact with water, necessitating that larger pieces are often displayed behind glass to prevent accidental damage.

Material Composition and Binders

The composition of watercolour and gouache also varies. Both use gum arabic, a tree sap, as a binding agent. However, gouache contains additional materials to achieve its opaqueness. Common additions include calcium carbonate or chalk, which form a chalky base for the color pigment. Watercolour can sometimes be made opaque by applying it thickly, but it is more commonly used to create transparent or translucent effects.

Techniques and Applications

Technically, the handling of watercolour and gouache differs significantly. Watercolour allows for a more fluid application, including techniques such as glazing, wet-in-wet painting, and splattering. These techniques yield a more fluid, layered appearance that can be quite textural. Gouache, with its opacity, behaves differently. Painting in gouache often requires a heavier application to achieve the desired opacity and can be more challenging for achieving subtle variations. Nevertheless, gouache can be used to paint from dark to light, much like oil, although the transition might not be as smooth.

A Personal Perspective

As an artist, my personal experience with gouache has been quite instructive. I find that while gouache offers a unique set of challenges, particularly in maintaining clear and vibrant hues, it is incredibly rewarding when used correctly. Many watercolourists keep a tube of white gouache handy for touch-ups, adding highlights or blotting out mistakes. However, for strict watercolour purists, this practice is somewhat frowned upon. Despite this, gouache can be used to create transitional, semi-opaque effects, making it a versatile medium that can bridge the gap between watercolour and oil painting.

In conclusion, while both watercolour and gouache are water-based and can be used with similar brushes, their differences in opacity, handling, and composition make them uniquely expressive mediums. Whether you are a watercolourist looking to add a new dimension to your work or just starting out, understanding these differences can greatly enhance your artistic process. Lena Rivo's work in gouache is a testament to the medium's depth and versatility. Her videos provide valuable insights into the techniques involved, encouraging artists to explore the unique qualities of gouache further.

Remember, whether you are opting for the clarity and transparency of watercolour or the versatility and opacity of gouache, the decision ultimately lies in the artist's intent and the desired outcome of the piece.