Tone your canvas, trick your eyes

There’s science—okay, at least pop science—behind the idea that a bright white canvas will distort your painting.

One example of the Delboeuf Illusion, courtesy Wikipedia.

Why tone my canvases?” is perhaps the most common question oil-painting students ask me. It’s all about optical illusion. The size, shape and color of the objects we paint are influenced by their background.

The Delboeuf illusion is a distortion of relative size. In the illustration above, the two black disks are the same size, but one is surrounded by a tight ring; the other by open white space. The human eye sees the surrounded disk as larger than its non-surrounded twin.

The Delboeuf Illusion is in pop-science news these days because psychologists have found that people who eat meals served on smaller plates have a tendency to feel fuller faster. Oddly, animals also display food preferences based on plate size, but they don’t always correlate to our reactions. Dogs, for example, go for bigger plates. Dogs are such unwilling dieters.

One example of the Ebbinghaus Illusion, courtesy of Wikipedia.

Closely related is the Ebbinghaus Illusion, in which perception is influenced by the presence of nearby shapes. In the example above, the circle surrounded by a ring of large shapes appears smaller; that surrounded by a tighter ring of smaller shapes appears larger.

In both examples, if the shapes were all on a neutral-value ground, the contrast would disappear and the illusion would be broken.

Susceptibility to the Ebbinghaus Illusion is strongest in those with highly-developed visual cortexes (such as artists). It’s context dependent, so little children fall for it less often than adults. That would indicate that these visual cues are part of how we learn to navigate our environment. Relative size is a big clue to how far away an object is.

Sarcone’s Cross Illusion, courtesy of Wikipedia.

Sarcone’s Cross is an illusion that works in the opposite way. The cross dwarfed by large black squares appears larger, not smaller. The takeaway lesson for artists is that there isn’t an easy way to predict how the color and value of neighboring objects will influence what we next put down on paper or canvas. However, we can be sure that they will. This is why value studies are such an important part of painting design.

All of these optical illusions are explored in color in Josef Albers’ classic textbook, Interaction of Color. It may not be that much help on a practical level, but it’s great fun to think about.

One of Josef Albers’ experience on space illusions, from Interaction of Color, courtesy Yale University Press.

So, what does this have to do with toning? Toning is invaluable in the initial stages of a work because it changes how you perceive masses placed on the canvas. A toned canvas helps the painter establish a pleasing value structure.

There are many fine painters who don’t need a toned ground to produce a fine painting. If our reactions to these optical illusions are learned, then it’s possible to unlearn them (or at least learn to compensate for them). But why work that hard when a simple sweep of color on your canvas will save you a lot of work?

None of this pertains to watercolorists, of course. The white of their paper is part of the design, and that makes the illusions part of their magic.

Monday Morning Art School: Tone your canvases

Toning makes a difference in how you see lights and darks.

Bracken fern, by Carol L. Douglas. Available through Maine Farmland Trust, Portland, ME.

Imprimatura is the initial stain of pigment painted on a gesso ground. In indirect painting, this color is left open where possible, reflecting back up through the paint layers and creating a cohesive tonal structure.

We don’t paint indirectly in the field, so why do we still tone canvases? Toning is invaluable in the initial stages of work. Not only will a white canvas blind you on a sunny day, it changes how you perceive darks and lights. The tendency when painting on a white board is to start your darks too dark. A toned canvas helps the painter establish a pleasing value structure. We touched on this in our Monday Morning Art School lesson based on Josef Albers.

I use a clapped-out oil-painting brush, but a 2″ wall brush works just fine and is cheaper.

Traditionally, artists chose a warm earth tone like a sienna or ochre, diluted it half-and-half with turpentine, applied it on the canvas with an old brush, and then wiped the residue off with a rag. This is still the best way to tone, since it leaves a layer porous enough to grab the gesso, but in a light, sparkling manner.

With oil-primed canvas and boards, you absolutely must tone that way. While oil paint can be applied over acrylic, acrylic must never be applied over oils. It delaminates. There are some fine painting boards with oil primer, and it’s easy to confuse them with the more common acrylic-primed boards. Read the labels. 

If you’re painting in acrylics, you must use acrylic primer and you cannot use an oil-primed board.

A more traditional toning color, and a frankly bad application. I can say that; I did it.

There is no reason that oil painters can’t also tone acrylic panels with oils, however. It will give you a slightly smoother painting surface, and it’s a good use for leftover paint. However, to save time, we often tone acrylic-gesso boards with acrylic, treating the tone as an extension of the ground rather than as the first layer of the painting.*

Alla prima painters often let the board show through in some passages. What color you want to show depends on your own taste, so I recommend experimenting. Traditionally, painters used earth tones—the ochres, umbers and siennas. I prefer 20th century pigments, so I’ve tried red, lavender, orange, yellow, and blue. I think our predecessors had it right: warmer tones work better.

Birch board is sealed, not toned, allowing the wood color to shine through.

I toned with naphthol red for several decades. I got that idea from Steven Assael, who probably got it from someone else. It’s a good counterpoint to green and blue, the dominant colors of our northeastern environment. It’s energetic, which I aspire to be, and it makes me immediately think in terms of all the accidental colors in the environment.

However, I’ve been experimenting with painting on plain birch panels for the past two seasons. These come naturally-toned, as long as one uses a clear sealant. That points out the basic character of imprimatura—the hue doesn’t matter nearly as much as the value does.

Safety check, by Carol L. Douglas. Available.

Toning makes a terrific mess. Cover your work surfaces. Smooth application isn’t a priority. If you’re toning with acrylics, you don’t want to wipe out the excess so much as mix it to the proper consistency at the beginning, paint it on, and let it dry. In either case, don’t over-coat your canvas; you still want the luminosity of the board to show through.

Acrylic paint manufacturers say you shouldn’t dilute acrylic paint more than 50-50. That’s true even at the toning level. If it’s breaking down into droplets, it’s got too much water in it.

*I recently had a student underpainting in acrylics. I investigated this myself a long time ago and abandoned it for two reasons. The first is that it requires two full paint kits in the field. More importantly, the underpainting becomes part of the ground, rather than the painting. If these are separated for some reason (like relining), there goes the bottom layers of the painting. Far better to just learn to apply the underpainting properly in oils.

The corrosive power of chance remarks

Words have the power to inflict or bind wounds. May we choose ours carefully.
Posted, by Carol L. Douglas. Watercolor on Yupo paper. I never did figure out a color for those water-lilies.

I was checking into an event when the canvas-stamping person said, “Oh, you paint on a red ground? I’ll have to check your work out. A lot of people do that near where I live, and I hate it.”

I have no idea what—or even if—she was thinking when she said that. But it has subtly affected me ever since. I’m finding myself less likely to leave the ground showing, more likely to lard the paint on. Neither is good technique.
I’m a confident painter. Imagine if I was less experienced, or less secure. It might have completely shaken a painter at the start of a competitive event. It’s a perfect example of how not to offer criticism.
Private Island, oil on canvas. This was interrupted by headache last week.
Compare that to my dear friend Mary Byrom, who doesn’t like that red ground either. Mary is a crackerjack painter herself. I know she has good technical reasons for her opinion. She is also a loyal, kind, supportive friend. I know her intentions are good. I can listen to her opinion and weigh it fairly, without being defensive. She’s earned the right to critique my painting.  
I’ve spent the month looking at and absorbing Joseph Fiore’s paintings, and I plan to start tinkering with some of his technical approaches, particularly his surfaces and scribing. He clearly—and successfully—paints on white canvases. He leaves areas white, scrubs the paint back, and lets the ground show through.
After checking every day this week, I decided I had to paint the reflections from my sketch, because there’s a constant breeze on Damariscotta Lake right now.
Toning, for those of you who aren’t painters, means painting the white gesso a color before you start the painting proper. I was taught to always tone my canvases, and it’s something I also teach my students. Of course, the way I learned was to lightly tone with an earth tone in sepia, yellow ochre or grey. The brilliant red was a later addition.
Toning is as old as painting itself, but its rationale is explained through the 19th century concept of simultaneous contrast. This is a fancy way of saying that a color looks lighter against black, darker against white. To see it accurately, you need to see it against something that’s a neutral value.
Toning:
  • Establishes the mid-tone values from the start;
  • Unifies the color of the composition;
  • Sets an emotional tone for the painting;
  • Stops any specks that peek through from competing with your highlights;
  • Gives you a more accurate sense of the value and size of your darks when you first set them down.
In the field, it also stops you from being blinded by brilliant white.
Working Dock is the painting I showed you yesterday, properly photographed this time. (I finished it at dusk.)
From observation, I’d say the majority of my plein air peers start on toned boards. It is something I’ll continue to recommend to my students. But should I keep doing it? That I can’t answer until I experiment on a white canvas. And that will wait until this workshop is over, because I only brought toned canvases with me.
While I’d like to say I’m thinking through this as a response to the Fiore paintings, there’s a small niggling part of me that’s still reacting to that woman’s comment. It’s a reminder that words have the power to inflict or bind wounds. Good advice is invaluable, in painting and in life. But may we all be as kind as Mary Byrom when we offer our opinions.

Toning canvases

I tone my canvases bright red because it works for me, but you can choose any warm color. The important thing is that you always do it.

I use a clapped-out oil-painting brush, but a 2″ wall brush works just fine and is cheaper.

Imprimatura is the initial stain of pigment painted on a gesso ground. In traditional indirect painting, this ground color is left open where possible, reflecting back up through the paint layers and creating a cohesive tonal structure. Imprimatura was used the Middle Ages but became standard practice during the Renaissance.

We don’t paint indirectly in the field, so why do we still tone canvases? Toning is useful in the initial stages of work, since it helps the painter establish a value structure. Not only will a white canvas practically blind you on a sunny day, it changes how you perceive darks and lights, which in turn mucks up your composition. We touched on this in our Monday Morning Art School lesson based on Josef Albers.
A more traditional toning color, and a frankly bad application. I can say that; I did it.
Traditionally, a painter would choose a warm earth tone like a sienna or ochre, dilute it half and half with turpentine, paint it on the canvas with an old 2” wall brush, and then wipe the residue clear with a rag. This would leave a layer still porous enough to grab the gesso, but in a light, sparkling tone.
If you’re using oil-primed canvases or boards, you’d better tone exactly like that, or you’re creating an archival nightmare. Everything I’m about to say applies only to acrylic-primed boards, which are the ones most commonly used in the field.
I use diluted naphthol red for a ground. This isn’t something I made up myself; I got it from Steven Assael, who probably got it from someone else. (In fact, I keep meaning to ask a conservator whether it’s the right red, or if there’s an analog that’s more migration-fast.)
I want enough pigment to be solid, but not enough to interfere with the tooth overmuch.
I like naphthol because the color is warm yet hot, unlike cadmium red, which tends to be dull. (That’s a great attribute for a painting red, just not for a ground.) Naphthol red is a good counterpoint to green and blue, the dominant colors of our northeastern environment. It’s energetic, which I aspire to be, and it makes me immediately think in terms of all the accidental colors in the environment.
Beginning painters often make the mistake of being skimpy with the paint, especially if their earliest training was with watercolor. There is nothing more amateurish than watery paint on a white board. A toned ground encourages the use of proper amounts of paint, and it makes those first efforts look more cohesive.
So what color should you use? What are you going for in terms of mood and feel? The typical answer to this is the earth tones—the ochres, umbers and siennas, either solo or in combination. I tend to like 20th century ‘hot’ pigments. I’ve used lavender, orange and pink with success. Straight-up lemon yellow, however, was a dismal failure.
Spring Pruning, by Carol L. Douglas. Sometimes I let the ground show, as here.
Manufacturers say you shouldn’t dilute acrylic paint more than 50-50, and I think that’s true even at the toning level. If it’s breaking down into droplets, it’s got too much water in it.
Toning makes a terrific mess. Work on the floor, the lawn, or cover your work surfaces. You can kill yourself to apply the paint smoothly, but I never bother. It doesn’t seem to make much difference in the finished product.
This afternoon I leave for Rochester, NY for my Color, Composition and Technique workshop. After that, there’s a watercolor workshop aboard American Eagle, June 10-14, and my annual Sea & Sky workshop at Acadia National Park, August 5-10. Email me if you have any questions.