Archive for the ‘Color theory’ Category

Drying Shifts in Water-Based Media

October 29, 2018

With matte, water-based media—gouache, casein, or transparent watercolor—some pigments can suffer a shift in color when losing moisture. The reason for this is physical—the scattering of light, or some such physics thing. The reason this doesn’t happen to the same extent in oil paints is that they remain more or less “shiny,” continuing to scatter light similarly to they way they did before curing, which is close to the refractive index of the surrounding air (again: or some such thing—I never took a physics class in high school, and I’m sure it shows). When gouache or casein dry they effectively go from glossy to matte, so some change in color is to be expected. For a useful (if incomplete) reference on how different pigments behave in watercolor, check Handprint: watercolor drying shifts.

Many artists have learned to deal with this phenomenon. A quick image search for gouache paintings or casein paintings proves this amply. If you’re intimately familiar with your materials, you can keep an eye on which pigments you’re mixing, judge the drying shifts they’ll undergo, and adjust your mix accordingly—before laying it down. If you really know what you’re doing, you won’t be surprised by the result when it changes. Many, many good artists have learned how to do this.

Personally, I can’t deal with it. It freaks me out. I feel like I have enough trouble predicting how a color will look in a composition without having to worry about it changing on me after I lay it down.

Oh, I can handle it to some extent. I have to, if I want to use casein or gouache (which I do—the matte aspect means they’re easy to photograph and reproduce, which makes them ideal for illustrations). I can deal with some loss in saturation, and with small changes in value. But if either one becomes too drastic, I start losing my cool.

So I try to stick with the colors that have smaller drying shifts. One of the reasons I haven’t used natural indigo as much as I would’ve liked is that it loses much of what little saturation it has when it dries. Dry swatch is on the left:

Drying Shift Natural Indigo

Drying Shift Natural Indigo

What starts out as a lovely deep blue becomes something pretty close to gray. No fun! (Note: while I did paint the newer swatch a bit darker, the photo shows the dry swatch less grayed than in real life. I’ll let you know when I’ve conquered the skill of photographing artwork.)

One of the most dramatic value shifts I’ve seen is the “Ultramarine Blue Deep” in Jack Richeson’s Shiva brand of casein. It may be “deep” when wet, but that’s hardly an accurate description of the dried color. Dry swatch on the left:

Drying Shift Ultramarine Blue Deep

Drying Shift Ultramarine Blue Deep

I can’t use that paint. It just changes too much for me to manage it in mixes.

I told some folks at WetCanvas that this was the most extreme shift I’ve ever encountered, but when I wrote that I’d forgotten about my experiments with egg tempera some years ago. My rose madder pigment in egg tempera might have had an even larger shift, with the beautiful deep crimson changing back to the dry pigment color, which is a faded pink. Again, not usable, for me at least.

PBr24 also has something of a drying shift. Luckily, the tube I have happens to be from Schmincke, where they’ve tried to help out with this. Check it out, dry swatch on the left (note: colors are significantly more orange than IRL):

Drying Shift Titanium Gold Ochre

Drying Shift Titanium Gold Ochre

See what they’ve done there? The color displayed on most paint packaging tends to have only a vague relationship with the color inside the tube or pan. This label matches not the paint color in the tube, but the paint color as it will be after it’s dried. And that, my friends, is one of the things that set Schmincke apart from their competitors.


The Student Palette

November 27, 2011
Portrait using Student Palette

Portrait using Student Palette

The oldest palette, according to the story of the previous post here, has been in use for about a hundred thousand years or so. The palette consists of black, white, red ochre, and yellow ochre: these are the colors that have been used in cave paintings for all of our long prehistory, readily available and easily processed and used. Black, white, red and yellow are often the earliest colors to receive their own names in a culture, and I hypothesize that that’s precisely because those are the four colors that are universally in use. Pliny the Elder mentioned that the great Greek painters used the colors Attica earth (yellow ochre from Attica), Sinoper (red ochre from Sinope), black and white. And earth reds and yellows, plus black and white, have made up the greater part of easel painters’ palettes since the Renaissance (at least up until the Twentieth Century). This basic palette of earths and neutrals has been called the student palette, because the paints it uses are so inexpensive, and also because the restricted palette is an excellent learning tool.

Working with such a restricted palette has its own challenges and rewards. One challenge of using earth colors only is that they lose saturation quickly in either tints or shades. Another is that it’s difficult to avoid a monochrome look to the painting. But, with patience, it’s a palette that does work for portraits. The reason it works, aside from the fact that earth colors mixed with white naturally resemble skin tones, is something called simultaneous contrast. Simultaneous contrast means that colors have an effect on each other’s appearance when placed side by side; in particular, they tend to push away from each other, perceptually. What this means, practically, is that you can get a blue in your painting without actually using blue – a neutral gray will appear quite blue when placed among warmer colors (a mix of black and white actually is slightly blue, which heightens the effect). And a serviceable green can be had from a mixture of black and yellow ochre (in addition to the simultaneous contrast effect, dark yellow, or olive, actually looks quite green to the eye even by itself).

Sketch of Joy, student palette

Sketch of Joy

The benefits of working with a student palette: first of all, it teaches how to make effective use of this simultaneous contrast. (I think half or so of the so-called Old Master Techniques were developed simply to deal with the lack of inexpensive blue pigments, and this is one of them.) Also, one simply learns a lot about mixing with earth colors, which must be an integral part of any traditional palette – and about paying attention to values, since the student palette simply doesn’t work without good value contrast. Finally, crucially, one learns how to make a painting work without trying to match all the colors you see in front of you. Modern painting practice seems to be all about matching colors; but if you literally cannot match the colors in front of you with the paints you have available, what do you do then? Can you still make the painting work?

I wouldn’t necesssarily use this restricted of a palette in professional work – as I mentioned in the previous paragraph, you just can’t get all the colors you might need. But as a study it’s invaluable, and I definitely recommend it.

Portrait using the student palette

Portrait using the student palette

The four paintings on this page were done with variations of the student palette, and were painted alla prima (though the one at right took an extra few minutes in a second session to block in the background and the shirt). The painting at top was done using Blue Ridge Yellow Ocher, Ercolano Red (a light red) and bone black, all from Rublev, plus zinc white from Winsor & Newton. Notice the blue shirt, painted with black and white, and the green background, painted with black, white and yellow. The second painting on the page is a quick sketch from life of my wife singing and playing the piano (the other three are all painted from photo reference at the WetCanvas Reference Image Library), using the same palette as above. The painting just to the right of this paragraph was done with a slightly expanded student palette, using two red earths: the same yellow ochre and ercolano red from Rublev, plus Venetian Red (also from Rublev) and substituting Da Vinci Magnetite Genuine for the black, and Rublev lead white in place of the zinc. Other helpful earth colors can be added, of course, including raw umber, burnt sienna, terre verte, et cetera. Below is an experiment using a very limited palette indeed: Venetian red, burnt umber and zinc white only.

Venetian red, burnt umber, zinc white

Three tubes of paint

The temperature variation on all of these is very limited (though I managed a bit on the third painting), partly through my lack of experience with this palette, but mostly because they’re all painted opaquely. A good deal more variation can be achieved by taking advantage of transparent effects, and I’ll be exploring that direction in the future. Some additional reading: George O’Hanlon discusses painting with earth colors here, and here is a discussion of Marvin Mattelson’s use of earth colors for skin tones.

Colors “straight from the tube”

March 21, 2010

Attitudes have certainly changed over the centuries regarding how we treat our colors when painting a picture, and much of the changing approaches are directly related to the questions of what pigments are available, and how expensive and difficult to procure they are. Much of what one reads and hears currently concerning color theory and ways of approaching a painting, other than color relationships, is concerned with mixtures of paint colors: Which colors will mix to produce a warm shadow, what mixture of colors will most accurately represent what I’m seeing here, and can I really get a good skin tone by mixing all these colors on my palette? This approach seems obvious to us – after all, one cannot accurately describe most real-world objects or scenes using paints straight from the tube, they are simply too bright and saturated. Most of the real world that we as artists are trying to depict falls into a much less saturated range. Concentrating on mixtures of colors generally seems to be the only reasonable approach, and so obvious it barely merits attention.

However, this approach was not always quite so obvious or accepted as it is to us today. There was a time when pigments were used much more often in pure, unmixed form in paintings – and this had much to do with a regard for pigments that was born of their scarcity and percieved inherent value. During the Middle Ages, when bright and purely intense colors delighted the eye to an extent not seen again until the twentieth century, mixtures of colors were used when necessary but were not considered ideal. Writes Daniel V. Thompson concerning mixed greens in medieval painting:

We are justified in believing that mixed greens were common in medieval painting; but we could easily allow ourselves to overstress their importance. In general, medieval painters did not much like to sink the individuality of their hard-gotten colours in complicated mixtures. Mixtures of more than two or three pigments were not popular, and there was a decided preference for achieving effects with single pigments, displaying their characters to the best advantage. (The materials and techniques of medieval painting, Daniel V. Thompson)

Mixing a color was sometimes even referred to as its “deflowering.” Some of this approach had to do, certainly, with a lesser necessity for complex mixtures, since medieval painting (to probably grossly oversimplify) had less to do with achieving realism than did painting in later periods. Complex mixtures are required in order to accurately describe natural light falling over the more or less desaturated forms of nature – but not to create an icon whose purpose is to inspire feelings of worship.

Much of this approach by medieval artists, however, had to do not only with the comparative de-emphasis of realism in their art, but also with the high regard in which pure, bright pigments were held in their time. Bright, permanent colors were scarce and generally expensive. If an artist has spent all day making a lake pigment himself, or purchased costly materials from over the sea, finally to attain a precious lovely color brighter than any to be found in readily available local materials, would it then make sense for that artist to be eager to quickly dull that color down in mixtures? As someone who has labored to manufacture a few lake pigments myself, I wouldn’t think so.

For various reasons, including the growing scarcity of basic materials, I expect many of our modern colors to become more expensive in the future – perhaps much more expensive. If this happens, I will be very curious to see if we artists of the twenty-first century develop more of a medieval attitude to the inherent value of pigments (among other things, perhaps to the dismay of modern relativist economists); and, in painting practice, the preservation of the purity of colors.