Color Wheel

Color wheels

We arrange our oil color tubes on a rotating circular tray that has two tiers. The tray serves several functions. First a rotating tray gives us ready access to all the tubes without having to rummage around in a paint box. We use many colors for every painting—sometimes only tiny amounts from each—and we don’t want to compromise our range of color out of impatience with finding a tube. Second, we have arranged the oils in the order of a typical color wheel, across the color spectrum from yellow to violet. There is a photo of our double-layered paint tray under the section called “Painting with Knives”. The tray is made of a lazy susan with circular pieces of thin plywood on top to extend the surface. The top layer is a piece of scrap carpet that keeps the tubes from sliding around. Hanging above the tubes of paint we have two color wheels that correspond to all the colors on the tray. See photographs of them on the left. The wheels enable us to get a quick idea of the distance on the color spectrum of each tube of color. The proximity of two colors on the spectrum is very important because the closer two colors are on the spectrum the more brilliance will be retained in the result. Mixing colors that are across from one another on the spectrum will dull the brilliance “desaturate” the resulting color. Finally, the two-tier system enables us to separate the earth colors from the others. Earth colors, so-called because they are compounds of iron, are arranged on the upper tray while all the other colors are arranged on the lower tray. By separating our oil colors into these two collections we can more easily maintain the “fat over lean” rule of oil painting. The earth colors, by and large are “leaner” (they absorb less oil) than the others. When possible leaner colors should be laid down first. Moreover, the earth colors are less saturated (brilliant) than the other colors and dry more quickly. The saturation or brilliance of a pigment is very important because it enables us to create the illusion of depth and lighting effects by using the desaturated colors in the depth or shadows and more brilliant colors for the highlights or lighted areas.

The ground

Before applying any paint, the surface of the panel must be prepared by sanding, to roughen it, and by applying a layer of paint called a “ground”, a coating that bonds with both the panel and the oil colors. Until recently we used a procedure that has been used for hundreds of years, three coats of hide glue, applied hot, followed by two coats of oil primer. Today we use an acrylic “size” followed by an acrylic Gesso. We resisted the acrylic coatings because we were not certain that they would bond well with oil paint. However, paint chemists have informed us that good quality Gesso today is formulated to be porous, allowing the oil to make a strong mechanical bond with the Gesso even though the oil does not make a chemical bond with it.

Hardboard panels

Panels seen from the back

We paint on hardboard, as many knife painters do, not on canvas. Thick applications of paint could break if the canvas were rolled. Many of the great masters painted on natural wood or hardboard panels, including Picasso. The problem with natural wood is its tendency to crack or “check” over time. Hardboard is essentially homogenized wood, so it doesn’t crack. (Many of us are more familiar with the name “Masonite” than “hardboard,” but we cannot use the name “Masonite” anymore since it is copyrighted. Calling it “hardboard” avoids this copyright problem.) Hardboard is made by exploding wood fibers with steam and then pressing them back together into sheets without any additives or glues. The lignins and other natural substances of the wood hold it all together just as they do in the original wood. To prevent warping, we back the panels with a frame, as you can see in the picture to the left.

Painting with knives

Palette knives

People are often surprised when we tell them that we use painting knives instead of brushes. They point to some fine lines on a painting and ask if these were also painted with a knife. Yes, they were. We have some brushes somewhere in the studio but we rarely use them. For people who have never heard about knife painting we have to explain that painting knives are not like kitchen knives. They are more like miniature spatulas, usually triangular in shape. The photo on the left shows the large collection of knives that we have gathered over the years. Below that photo is one of my palette with the knives in plastic cylinders. By this arrangement we can use 10 different colors at a time, each one on a separate knife. We prefer knives because they allow us to control the colors better than we can with brushes. Years ago, when we used brushes, we weren’t able to clean a brush between every application of paint.  Consequently the brush continually mixed the pigments, making them muddy or desaturated. With the knife we can apply the pigments straight from the tube, wiping them between applications, so that the colors remain pure and bright. Where desaturated colors are needed, of course, we can mix the desired level of desaturation.Another reason for painting with a knife is that it allows us to sculpt the surface of the paint so that each object reflects light as it would in real life. This gives the painting a depth that we could not accomplish with a flat surface. A field of grass looks soft because individual blades scatter the reflected light. When painting grasses or pine needles we use the edge of the knife, making thin ridges of paint that give the surface a third dimension. The ridges break up the light in the same way that real grass would, giving the surface a soft appearance. Hard, flat surfaces like bark on tree trunks reflect light in patches while the cracks in between trap most of the light and thus appear dark to the viewer. When painting bark we might underpaint with dark brown, then build up the bark by laying on flat plates of paint, and finally, when the plates have dried, use a technique called “scumbling” in which we run over the dry plates with our knives to add highlights, moss, or other features. Essentially, we are painting in three or four layers. The picture on the bottom left illustrates the result of this technique. The photo was taken at an acute angle so that you can appreciate the three dimensional quality of the paint.

Special Oil Colors

To use our knife technique we require highly viscous paints. Oil colors that are the consistency of jam are formulated to spread easily with a brush, but they either slide off the knife or form drooping strings that make precise control impossible. A thick and granular consistency is ideal for knife painting, but this consistency should not be achieved by the addition of fillers, which dull the colors. Dense pigments are more expensive but well worth it because they enhance viscosity without dulling the color. Several manufacturers make oil colors of a suitable consistency, but strangely no one manufacturer makes colors that are all free of what we call “stringiness”.


Daler-Rowney Artists Oil Colours, Winsor and Newton and Old Holland are particularly suitable in consistency for knife painting, but there are odd exceptions. For example Old Holland earth colors are the perfect consistency for knife painting but their Titanium White is stringy. We use Winton Titanium White oil color.

Readers who know their oil colors will recognize that Winton is the brand name for Winsor & Newton’s oil colors for students.  This color is the single exception we make to the rule that we always use “artist” quality oil colors rather than “student” quality.  The reason that we use Winton Titanium White is simply that it has the very best consistency for knife painting of any white we have ever encountered.  Is there a downside?  No.  There might be a downside if we were comparing Cadmium Yellow (artists’ quality) with Cadmium Yellow Hue (students’ quality) because manufacturers substitute less expensive pigments in the students’ oil colors for their more expensive counterparts in their “artists” or “professional” lines.  The students’ colors  are sometimes not as brilliant or durable as the artists’ colors.  But Titanium is Titanium.  If it might be a little less opaque than the artists’ pigments the difference would never be noticed in the thick applications that we knife painters use.  Someone who paints with thin washes may be able to detect the difference.  Meanwhile, for knife painting, it’s gorgeous.