I live in Los Angeles for 7 years now. The sky here is very much blue, something it took me time to get used to after other, grayer cities. Painting a beautiful blue sky in watercolor sounds very straightforward, but it's actually a difficult task. There's the whole thing about gradients and paper and dilution of course, but this can be solved with a little exercise and some very good paper.
The biggest problem is actually color. We, has humans, have a usually good notion of a medium blue. I looked up for a medium blue of 475 nanometers, and found quite it unsettling : it's exactly as I imagined it. We all have different versions of basic colors, our own cultural and personal palettes. It's normally impossible to imagine a universal, medium color.
It's difficult to define red, some see it more tomato, others more carmine, yellows are even more difficult and green don't even think about it, but blue, we have a good notion. It is quite interesting if you think about it. Is it because of the very little occurrence of that color in nature apart from the sky?
If you want to sketch a clear blue sky you know what you want to show, wouldn't it be nice to have the exact right blue (or blues) in your palette?
Problem: There's not so many blue pigments.
And even if you can get the right hue, the right saturation and values are hard to find if not impossible. The sky, pure blue sky, is blue because of Rayleigh scattering : particles in the atmosphere scattering the blue light more than red. It's the light of the sun, scattered. It's more luminous than paper, more luminous than any paint.
I made tests : Prussian blue is too dark and green and not enough saturated, phthalo is too green and too intense, ultramarine is nice as a touch but a bit too dark and purple...this, for the not obviously, classic historical pigments that are lightfast and easy to find. I tend to prefer non toxic pigments or not too toxic paints because my cat loves to drink my paint water. She also is very fond of napping in my palette, something I can't really understand. You probably have to be a cat to find sitting in sticky paint comfortable. I also look for paints with only one pigments at first when building my palette. For exemple, I quite like Verditer blue from Daniel Smith, but it's made of 3 pigments including a gouache-ey white, a lovely color but probably not the best building block for a restricted palette. So I continued my search for nice paint made from possibly only one pigment with a historical background.
I couldn't find a nice blue for my Californian sky. It was very disappointing. I made some research for grays and discovered that cobalt made some delightful cold grays mixed with raw sienna. I tested it but then hesitated. What a beautiful blue. But a bit toxic. I need a cat proof desk. My family is otherwise aware of the dangerousness of paint, something I'll get back to in another post.
I looked around for solutions. Richard Parkes Bonington has some beautiful blue skies. John Sell Cotman, too , has delightful, intense blues. So I looked up what kind of paints they had access to in their time. It could be ultramarine, prussian blue...or it could be cobalt. It made me go back to this pigment.
I had some cobalt tucked away, two small tubes, from Sennelier, and Winsor & Newton. Both are the same pigment composition, PB 28, but unlike phthalo green or some other colors that are fairly consistent through the spectrum of brands, I was surprised to discover that the Sennelier cobalt was more ultramarine (reddish) than the Winsor & Newton. It doesn't show much after scanning a RVB picture, but in reality the difference is more visible. Both are beautiful and intense and will make deep saturated skies, combined with other colors for depth. Cobalt blue turns to lovely greys once adding a touch of light red (PR102) or raw sienna , which makes creating clouds a real fun task. So it makes it a very lovely addition to a small, summer sketching palette.
And doing more research, I found out that the closest pigment to that magical medium blue is coeruleum ( of course) .
Cerulean blue is a good color, and something the great painters of the nineteenth century had access, too. But a real one (PB 35) is difficult to find . I bought a Daler & Rowney one.
It's almost the right thing for a French sky, a nice, medium blue with a beautiful granulation, but not quite intense as one would like. There's a hint of green in it, that you can find in some skies, but It's not quite as intense as cobalt. This said, it's a lovely color to add to a palette, as it makes lovely mixes with other colors. Here too, there's a warning on the paint toxicity. It isn't very toxic, but if you paint a lot you might want to pay attention. If you add it to your palette, don't lick your brushes, stain your hands, and dispose of the paint water properly.
So...I'm ready to change my palette, again!
But I will make sure the cat can't sleep on it.
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