It’s Optical Mixing Season

 

9/27/23 Optical color-mixing: Luminance and Lightfast colored pencils in Field Notes Streetscapes sketchbook (photo reference)

There must be something about autumn that puts me in an optical color-mixing mood. Maybe it’s because it was in the fall two years ago that I took Sarah Bixler’s color temperature workshop, which reignited my fascination with the concept. Or maybe it’s because I often use secondary triads in the fall, and they can be especially beautiful when mixed optically. In any case, I’m back in the mood.

For my most thorough discussion of optical color mixing, see this post from last year. In a nutshell, optical mixing occurs when transparent colors are applied in a way that allows individual hues to be visible if you look closely enough (like Pointillism or pixels). The eye does the work of mixing the colors together. Alternatively, when liquid paints are mixed first on a tray or palette, the pigments are physically blended together.

As further discussion of optical mixing, I thought I’d show examples of the opposite –  colors that were not optically mixed. Since water-soluble colored pencils are, by nature, mostly transparent pigments, some examples are not clear cut, but I dug through my files to see what I could find.

Interestingly, I found very few examples of fully blended colors using activated watercolor pencils, and that’s because I tend to favor the optically mixed look, even when more thorough blending is easily possible. In the case of the still life below (full sketch in this post), I used activated watercolor pencils, blending them more thoroughly than I usually do. (Compare the water-activated produce with their cast shadow, which I left dry – purple and green optically mixed.)

9/26/22 still life detail; Museum Aquarelle watercolor pencils on Canson XL 140 lb. watercolor paper

6/11/23 Kuretake Gansai watercolors in
Hahnemuhle sketchbook (photo reference)

I also found a few examples of watercolor sketches made during the 30 x 30 Direct Watercolor challenge, when I pushed myself to mix colors directly on the paper instead of on the tray as much as possible. For the foliage at left, I applied a good wet wash of yellow, then charged in the blue, which blended almost completely as if I had mixed the green in the tray.

In dry colored pencils, I found this recent example of a portrait of my grand-niece (below). For her skin, I applied many colors in multiple, light layers. My goal in this case was to blend all the pencils as smoothly as possible so that the individual hues would not be apparent.

8/19/23 Detail (Polychromos pencils on Derwent Lightfast paper; photo reference)

Finally, I have an example of what might be the most opposite of optical mixing: This small sketch was made with Haiya oil pastels on purple construction paper (below). Granted, I don’t know what I’m doing with oil pastels, but I find them to be so opaque that whatever colors are underneath do not show through successive layers at all – perhaps similar to gouache or oil paints. They do blend when pushed and smudged together, but then they are acting more like a liquid medium than dry. (What a weird medium oil pastels are! They are not liquid, but they are so greasy that it’s hard to think of them as dry! You’ll notice I didn’t scan the image – I couldn’t bear to get my scan bed greasy!)

9/24/23 Haiya oil pastels on construction paper (photo reference)

As for optical mixing, the topic of this post, I was all set up to experiment on location from my mobile studio, but last week it rained so much that I knew my windshield wipers wouldn’t be able to keep up. Instead, I spent some rainy time indoors with photo references. Using the same primary triad in both sketches (Derwent Lightfast Yellow and Mid-Blue and Caran d’Ache Luminance Purplish Red), my goal was to allow individual colors to show through so that the viewer’s eyes would do the work of mixing (top of post and below). These were simple experiments using only three basic colors as a warm-up, but I plan to eventually try more complex mixes, too.

9/27/23 Optical color-mixing: Luminance and Lightfast colored pencils in Field Notes Streetscapes sketchbook (photo reference). Enlarged like this, it's easier to see the "pixels" of individual colors, but at actual size, your vision does the work of blending them together.

Both about A6 in size, these two sketches each took about 20 to 30 minutes, which is also the range of time I typically spend on A6-size sketches in the field. I’m tickled about that, because it means it is possible to achieve the look I want (the degree of color intensity and contrast) with dry pencils without taking more time.

(By the way, as I like to do in the field, I am deliberately using a cross-denominational mix of Caran d’Ache and Derwent pencils with these non-soluble experiments. Why? Unlike my full loyalty to Caran d’Ache when it comes to watercolor pencils, I’m not as enamored with Luminance. In fact, I’m almost ready to declare Lightfast my favorite. Not yet, though.)

What do you think about this optical color mixing concept? If you’ve tried it, what media did you use?