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How to Paint Watercolour Skies with Paul Riley

Posted on Thu 12 May 2016

The chromatics of a blue sky are applicable to all media – the names of the paints are basically the same, it’s the behaviour of the pigment that is different. I shall concentrate on the hues. A blue sky is redder directly overhead; as it grades towards the horizon it goes through a green phase until it starts to be affected by light reflected from the land.

Sky colours – the basics

For a red blue you could use ultramarine, but that precipitates, giving a grainy effect that does not look real. What is needed is transparency, so try Winsor blue (red shade) or phthalo blue, although that is not as red as ultramarine. You then grade into the Winsor blue (green shade) or you might like to use cerulean blue, which is green biased – but do check as ceruleans do precipitate. Cotman cerulean is transparent and dries much like phthalo blue. These pigment characteristics only apply to watercolour painting.

A graded wash is one of the first techniques in watercolour painting and is worth practising; the key is not to stop and fiddle – see the basic wash (below). You may wish to introduce more colour into the wash; I often add permanent rose, followed by raw sienna, towards the horizon. This gives a roseate hue that implies a little sunshine and relieves the monotony of the blue. If working in oils or acrylics the grading can be done using a hog-hair fan blender. For certain skies try subtle over-glazes of cerulean and ultramarine.


Sometimes it is enough to include a particularly interesting development you have noticed. On the other hand, you can simply make it up! Why not? It is worth studying cloud systems – they are varied and fascinating. With a little knowledge you can look up and identify the various types, building up a mental library of shapes. All forms of cloud formation require special techniques to depict them, especially in watercolour. But once mastered, your sky paintings will never be boring again.

There are three basic ways I produce cloudscapes. The first is to leave cloud shapes out on the dry paper – diminishing shapes generate perspective in the sky. Once the paint is dry you tint in the shadow sides of the clouds – remember to note the position of the sun! This tinting needs to be a transparent grey, ideally non-precipitating; I use a delicate mix of phthalo blue and lemon yellow. If, however, you want to depict a malevolent stormy sky with lashing rain use indigo and raw umber, which will precipitate very well and you will get all the drama you need.

The second method, working on wetted paper, will give you soft clouds. Again, negative-paint the clouds, but if the paper is very wet they will bleed a lot. As the paper dries the clouds will merge less – judging the effect you need is born from experience. When the paper is dry, re-wet it and tint the clouds.

The third technique involves spraying the paper lightly with an atomiser, then painting the negative shapes again directly with a hake – this gives a hit-and- miss effect.

These methods can also be used one after the other, but allow to dry between each or you will end in a mess. Additional drama can be added by introducing splattering, sponging (for light shafts etc), picking (for stars), sanding for graded effects, and lifting with soft tissues – this is especially good for cirrocumulus.

Next time you are outside, look up and check out the sky, and then work out how to paint it using these tips.

How to Paint Watercolour Skies with Paul Riley
  • Basic sky wash

    Start with the board tilted very slightly. Proceed horizontally, keeping a wet edge. Drain off at the end of the wash. Cotman ultramarine (top) and intense blue (phthalo blue).

  • Graded wash

    Proceed as for a basic wash but vary the tone and colour. From the top: Cotman raw sienna, intense blue (phthalo blue), ultramarine blue.

  • Stains

    Stains are best for clean, clear skies. From the top: Winsor blue (red shade), Cotman intense blue (phthalo blue, a green shade), Cotman cerulean blue hue, Cotman permanent rose.

  • Precipitating blue pigments

    From the top: Schmincke Horadam ultramarine blue, Winsor & Newton Artists’ watercolour cerulean blue hue and manganese blue, Schmincke Horadam cobalt turquoise.

  • Precipitating tertiary colours for stormy effects

    Cotman indigo, raw umber and ultramarine.

  • Basic technique for painting clouds

    Paint the blue of the sky leaving cloud shapes behind – large at the top, small towards the horizon. Note I have tinted the right-hand clouds using a delicate grey.

  • Wet-into-wet

    Wet the paper, let the shine go, then add the colour slightly stronger than usual (the existing water will dilute it). Leave behind cloud shapes – big ones – or the colour will run together and the clouds will disappear. If necessary re-wet the paper (when dry) and tint the white clouds.

  • Splattering

    Instead of wetting the entire surface of the paper sprinkle with water using a spray bottle then proceed to paint. You will have a hit-and-miss effect of dry brush and bleeding strokes!

  • Cirrus and cirrocumulus

    To obtain the wispy effect use a fan brush or a hake with concentrated pigment and gently float onto the paper. For the mackerel effect use rolled up kitchen roll and blot out the wet colour. Be quick!

  • Storm Passing

    Storm Passing, watercolour on Saunders Waterford Cotton Rag 140lb (300sm), (26x36cm)

    I used torn card to apply masking fluid for the clouds, the sun was torn out of a masking tape disc and the ‘wafts’ of rain were masked out with tape. Colour was wiped on and off using a soft natural sponge.

  • Sun Halo

    Sun Halo, watercolour on Saunders Waterford Cotton Rag 140lb (300sm), (26x36cm)

    This is a phenomenon caused by cirrostratus cloud. I used a specially designed compass brush for this plus a compass cutter for cutting out masking tape. A little body colour was used for the white clouds.

  • Paul Riley

    Paul runs residential courses from his home and studio in South Devon. The next sky painting course, ‘Painting skies and autumnal colour’, is from October 23 to 28, 2016.

    For details see; email or telephone 01803 722352.

    This feature is taken from the July 2016 issue of The Artist. Click here to purchase your copy.


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  • He does not seek perfection in representation and refuses to reflect the outside world. In short, any work of art that exhibits an alteration of form and / or color. I want to recommend my favorite artists Pierre-Auguste Renoir, Frida Kahlo, Roberto Matta Gabino amaya cacho and Pablo Picasso.

    Posted by heidy barted on Thu 14 Sep 05:26:28