As I continue to revamp my watercolor palette and experiment with mixing, this past week I've been concentrating on the color blue. Since I like to field sketch and capture scenes in nature, the most obvious "testing ground" for blues in watercolor is how accurate the pigment looks when painting the sky.
Since I currently live on the coast, my goal was to choose a few blues for my palette that work well for painting both the sky and the ocean. To experiment with as many blues as possible, I completed more than a dozen quick watercolor studies that featured a prominent sky. Quite a few of those landscapes also included ocean or water scenes.
What I discovered surprised me.
I found out that almost any combination of blues can be used to create a realistic sky in watercolor, but no single blue worked well alone.
When I took the time to really study the daytime sky and what it looked like as the day progressed, I understood why.
Skies are never consistent in color, but there are some fairly consistent observations one can make regarding the sky. As you can see in the photo above, the blue that we typically associate with a sky color occurs right along the midline of the sky. As the eye travels higher in the atmosphere, the blue becomes deeper and more transparent, almost as if the sky is affording us a glimpse through to space.
The lightest blue usually occurs at the horizon line. At certain times, the horizon may not contain any blue at all but instead may appear as a mixture of yellows, crimsons, grays, or other hues that completely overshadow the blue.
Of course, clouds, humidity, fog, smog, or a host of other atmospheric changes or anomalies can totally upset these "rules," but regardless, your painting will always benefit by using multiple blues and even various other hues.
Below are some examples of the quick sketches along with the colors that I used.
I enjoyed using ultramarine more than any other blue. I loved the wide range of colors that resulted when muddied with the earth tones.
Phthalo blues or greens were a bit harder to use because phthalo's highly staining pigment doesn't lift as easily when creating cloud effects, but it can work when applied lightly.
I liked the bright transparency of the manganese hue. The ceruleans produced a lovely granulating effect... sometimes. Sometimes it wasn't so lovely in my inexperienced hand. Cobalt gets high praise from many artists when painting a sky, but I preferred the warmth of ultramarine.
Whatever blues I used captured the sky best when they were mixed with other blues or dirtied with the earth tones and streaked with bits of Hansa yellow, yellow ochre, permanent alizarin crimson, or Quin rose. These colors also worked well when depicting stormy weather or sunsets.
Again, I found no single blue that could accurately and beautifully depict a sky just by itself, but I am a beginner so there may be a way. For example, the sky in this sketch (above) was painted evenly using cerulean with a touch of ultramarine, and though I like the granulated effect, I think it looks a bit flat and needs an additional pigment. Multiple shades seem to capture the heavens best.
The best blues for a sky are quite possibly the ones you already have in your palette. These are probably the pigments that you know and love, and starting with these colors is the easiest way to begin.
Enjoy experimenting, and see you in the field!