Tips for Watercolour Glazing

Watercolour has become one of the most popular and versatile painting mediums over the last few decades, and there are countless different ways to use it. One method of painting that can be easily overlooked is the watercolour glazing technique, which relies on one of watercolour’s most unique and beautiful qualities: its transparency.

Tips for Watercolour Glazing

What is Glazing?

In its simplest form, glazing is a form of layering. It relies on thin, even layers of transparent paint, applied one on top of another, to develop colour and tone. It is a fantastic way to build up tonal value gradually, instead of going straight in with heavy colour. By employing this method of building up transparent layers, you can achieve a sense of luminosity and depth in your paintings, as well as bringing a greater sense of colour harmony to your work.

At first glance, the characteristics of a wash and a glaze are quite similar; the main difference is their purpose. Washes are large areas of paint that are laid down to create the overall sense of tone or colour. Glazes tend to be transparent layers of paint applied over existing parts of a painting that have already dried, to enhance the tone or change the colour of the underlying layer. They can be mixed from both pan and tube watercolour paint.

Transparency and Opacity

As this process relies on the transparency of the medium, it is important to check the transparency rating of your colours before you begin. Generally speaking, most watercolour paints will provide this on their packaging and will sit somewhere within the range of: Transparent, Semi-Transparent, Semi-Opaque, and Opaque. As a general rule of thumb, transparent pigments are the best to use for glazing and layering, as they allow the underlying colours to shine through.

Building up glazes of Jackson’s Burnt Sienna Artist Watercolour, a transparent pigment (PBr7)

Opacity is also affected by the quantity of water mixed with a watercolour paint. When heavily diluted, opaque pigments can show more of a transparent quality; and by the same token, when transparent pigments are applied at full intensity (i.e. with very little water added) they can initially appear opaque. For this reason, opaque or semi-opaque colours can also be used for glazing but will lack the clarity and luminosity that transparent paints can achieve. However, they can still be used to achieve different effects.

For example, we can compare Burnt Sienna, a transparent watercolour paint, with Venetian Red, an opaque colour. When heavily diluted, the Venetian red will appear to be transparent. However, when more layers are applied, the opacity of the pigment becomes more readily apparent. Likewise, the Burnt Sienna is also transparent when diluted; however, its transparency and luminous quality remains, even when multiple layers are applied to the same area. This is the reason why transparent colours are recommended for glazing, if the goal is to achieve clean, bright layers of colour.

Comparing the transparency of Burnt Sienna (left) and Venetian Red (right)

Single Pigment Colours

As well as the transparency of your chosen colours of glazing paint, it can also be worth taking a look at their pigment numbers. You can usually find these alongside the transparency ratings on most paint packaging. Many watercolour paints are created using a blend of more than one pigment, and the particular pigment blend often varies between manufacturers. For example, the Winsor & Newton Professional brand of Cadmium Orange paint contains two pigments: PY35 and PR108, while the Cadmium Orange from the Michael Harding Professional Watercolours paint range contains only one pigment: PO20. Single pigment colours are less likely to lose their clarity and become ‘muddy’ than those created using multiple different pigments, so they are more often the ones favoured for glazing; particularly when applying glazes in multiple layers.

From top: Jackson’s Indian Yellow Hue Artist Watercolour (PY83, PY93) and Jackson’s Yellow Ochre Artist Watercolour (PY42)

Staining Colours

It can also be a good idea to examine the pigment types in your watercolour paints, to see whether they contain staining pigments or not. Staining watercolours seep into the surface of the paper when applied, and this can make them challenging to lift out. However, this quality also makes them the ideal colours to glaze over, as previously applied layers are less likely to be disturbed by the application of fresh paint. For example, a Phthalo Blue is much easier to glaze over than a Cobalt Blue, because the Phthalo is a staining pigment and won’t easily lift.

Indian Yellow Hue glazed over Phthalo Blue

Uses of the Glazing Technique

A common use of the glazing technique is to alter the colour in certain specific areas of a painting. For example, a section that has already been painted with a wash of red might benefit from a thin glaze of transparent yellow in parts, to warm it. Similarly, a green area of a painting, such as a field or pasture in a landscape setting, might benefit in some areas from a thin glaze of a transparent blue to cool it. This is a useful way of adding depth to paintings, especially in landscapes, where warm colours tend to come forwards while cool colours recede. It is also a handy way to paint cast shadows. Glazing can also be used to enhance the colour harmony of a painting, by applying a thin layer of a single transparent colour carefully across large areas.

Another common use of glazing technique is to enhance the tone of a certain colour within a painting. By building up thin layers of the same colour over a single area, you can achieve a sense of gradual tonal difference as well as brilliant intensity in the areas you choose to place the glaze.

A single-pigment study in Burnt Sienna and Sakura Pigma Micron pen

Watercolour Glazing Colour Charts

A glazing colour chart is a handy reference tool that you can create, to help better understand the effects certain paints will have upon one another. It’s a fun way to experiment with a variety of different colour combinations, layering them up to see how they interact. Some colours will glaze together well; others will not.

To create a glazing chart, select a variety of colours, and paint several clean lines following one direction across your watercolour paper. Allow them to fully dry, then paint over them using the same selection of paints in the other direction, creating a cross-hatching of colour. Where the paint lines overlap, you will discover just how these different colours interact when layered, and see the variety of different and exciting hues you can create through this technique. Be sure to properly annotate your glazing chart with the names of the paints you have used, and, as a suggestion, your thoughts on the colours created.

Watercolour glazing chart, from top left: Burnt Sienna (PBr7), Indian Yellow Hue (PY83, PY93), Phthalo Green Deep (PB15:3, PG7), Phthalo Blue (PB15), Quinacridone Purple (PR122)

Watercolour glazing chart with Phthalo Green Deep (PB15:3, PG7), adding water incrementally for increased transparency

Tips for Careful Watercolour Glazing

Like any painting technique, glazing is not always as simple as it may appear, and proper application can take practice. The key to this type of layering is to wait until your first layer of paint is absolutely bone-dry, before painting additional colour on top. Otherwise, you risk disturbing the underlying layer of pigment and creating harsh marks, or patches of unintended lifting. Try to keep your brush strokes to a minimum, again to avoid disturbing the underlying paint; for this reason, larger brushes are generally recommended for glazing, especially those with soft bristles. Try to work quickly, and gently. It is also safer to go in with too pale a glaze to begin with, as colour can always be more easily added than taken away.

Glazing can be used to create a variety of different effects in watercolour painting, varying from the subtle to the dramatic. While it certainly isn’t for everyone, it’s a versatile technique that is well worth experimenting with. Adding different-coloured glazes can require a certain level of confidence, particularly when a painting is nearing completion, which is why tools such as the glazing reference chart can be so helpful. By building up these thin, transparent layers, wonderful depth, colour, and luminosity can be created using watercolour.

Further Reading

Recreating the Colour Palette of Winifred Nicholson

Tips for Painting While Travelling

A Guide to Watercolour Painting

On Location at Lutea

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