Reposted from John Muir Laws – Naturalist and Painter
Watercolor is a fast and effective medium for rendering skies. It allows the artist to play with gradients of color and value and hard and soft edges. Watercolor can create very pleasing cloud effects. This is helpful but it is also a trap. If you are satisfied with a cloud-like look you can create with a wet in wet technique, you may stop there and not spend time observing what clouds really do. Do not be satisfied with a technique that gives the look of generic clouds, train yourself to really observe what is happening in the sky and then use the techniques to render what you see.
Muted Sky Colors
Beware of most out of the tube blues. They are more intense than most of the colors you will see in the sky. You can mute an intense blue with the faintest touch of orange. A little goes a very long way so use restraint. In the example on the left, you scan see swatches painted with the pure pigment and then modified with a little orange for a muted hue.
The sky is richly blue overhead. As the sky approaches the horizon, it becomes lighter and warmer. This can be rendered with a graded wash. Start by mixing a puddle of paint that will be large enough to cover the area you are working with. Estimating this takes practice but at the start error on the side of having too much paint. You do not want to stop and re-mix half way through the wash. Most of my skies are small “landscapeitos” so I really do not need all that much. The mixture should be liquid, not thick like a paste.
Hold your paper or drawing board at about a 30˚ angle. This will make the water pool in a bead at the bottom of each stroke.
With a full brush stroke the top of the sky with a horizontal stroke. Use enough paint that the mixture flows down to the bottom of the stroke to form a bead along the bottom. Immediately reload the brush and stroke again, letting the mixture flow from one stroke to another. Do not pause or the paint will start to dry leaving a line. If you use the same unadulterated mixture all the way down you have a flat wash. If you start to add more clear water to the mixture you create a gradation from dark to light.
For most of my field work I use a waterbrush and only work a small area, as my whole landscape is small to begin with. With a waterbrush you get automatic graded wash effects as the pigment is replaced by the water in the brush that is drawn down by capillary action. I do not squeeze the brush as I paint a graded wash. This causes too much water to come out at once.
To paint a sky, I create a blue graded wash lightening toward the horizon. While the paper is still wet, I stroke the sky along the horizon with a pale wash of yellow ochre or a similar shade. The distant sky is not only lighter, it becomes distinctly warmer. This change in color temperature is the opposite of what you see on the ground. As the ground plane recedes toward the horizon it becomes lighter and cooler.
Graded Wash with Crayon Clouds
A wax crayon or an uncolored birthday candle is a terrific addition to your watercolor kit. If you scrub in a layer of wax before painting the sky, the wax will create a barrier between the pigment and the paper. The result is brilliant clouds with a sharp irregular edge. This approach is fast and fun when combined with the graded wash technique already described.
Once the paper is bone dry, scrub a crayon or candle stub along the edge of the area you want to be your cloud (top and bottom). Use a dense scrubbing motion. You do not need to add crayon over the whole surface of the cloud. It may be difficult to tell where you have put down the wax. If you turn your paper at an angle you will be able to see the sheen of wax reflecting in the sun.
Here are a few more examples of crayon clouds. Remember, the crayon goes on before the paint. Have fun and explore how to paint skies with watercolor.