Busted: Primary Color Myths

For 16 years one argument-causing myth has turned up like the baddest penny ever:

Painters can mix all colors from just the primaries. 

Usually the magic number of primaries is three. Sometimes there are five or six primaries, and sometimes the claim is made for three primaries and three secondaries. 

Confused yet? 

I’ve been using Munsell to mix the exact colors I want for 16 years now. Every day. A concern I hear often is that Munsell is too complex, too many colors, etc. (Put aside for a moment the cost of the The Munsell Book of Color, currently selling for $1,600. We’ll come back to that.) I also use Munsell to compose paintings, shift hues and chroma as desired and other cool tricky things, but that subject is for another time.

In the Munsell Color System there are 10 major hue groups and each of those is divided into four minor hues, for a total of 40 hues. Every color that can be mixed from contemporary oil paints falls within these 40 hues. In other words, every chip in the book can be mixed, and those mixtures represent all combinations of today’s available oil paint. The Munsell Book of Color provides glossy chips in 8 values (plus white and black) and in all the chromas possible for every hue. The chips are in chromas of 2, 4, 6, 8, etc. There are approximately 1,600 chips in the book sets, but for argument’s sake I am doubling that amount to 3,200 to allow for single chroma steps. These are often necessary and add much beauty to painting.

After much painting and color mixing it’s apparent that a minimum of 28 different tubes of paint are necessary to mix every possible hue in the Munsell set, and that set encompasses every color that can be mixed. So, 3,200 different colors are possible to mix with today’s oil paints.   

Here’s where it gets interesting:

The math behind the inability to mix 3,200 colors using only three oil paints is based on the concept of color space. A color space is a mathematical model that describes the range of colors that can be represented in a given color system. The three primary colors that are used in oil paints are red, yellow, and blue. These primary colors are the basis for all other colors that can be mixed from them. (If you already want to get the Digital Munsell set follow this link.)

To understand why it is impossible, we need to consider the concept of chroma, which is a measure of the purity or intensity of a color. Chroma is defined as the difference between a color and a gray of the same luminance. The higher the chroma of a color, the more pure or intense it is.

The three primary colors of oil paints have a chroma of 100%, which means they are pure and cannot be mixed from any other colors. When two primary colors are mixed together, the resulting color will have a chroma that is less than 100%. For example, if you mix red and yellow, you will get a yellow-red which has a chroma of about 50%.

The range of colors that can be mixed from three primary colors is known as the color triangle. The color triangle is a graphical representation of the three primary colors and the range of colors that can be mixed from them. The color triangle is a two-dimensional space, and the distance from the center of the triangle to each corner represents the chroma of each primary color.

The range of colors that can be mixed from three primary colors is limited by the color triangle. This means that there is a maximum number of colors that can be mixed from three primary colors, and this number is much less than 3,200. In fact, it is estimated that the maximum number of colors that can be mixed from three primary colors is around 1,000.

Another reason that it is impossible to mix 3,200 colors using only three oil paints is due to the principles of color theory and the limitations of the human visual system. 

To understand why this is the case, it is helpful to first understand how colors are represented and mixed. In the RGB color model, colors are created by combining different intensities of red, green, and blue light. Each color is represented by a set of three values, ranging from 0 to 255, which correspond to the intensity of each primary color. For example, the color red can be represented as (255, 0, 0), which means that it is made up of full intensity red light and no green or blue light.

The RGB color model is called an additive color model, because the colors are created by adding together different intensities of light. In contrast, the CMYK color model, which is used in printing, is a subtractive color model, because the colors are created by subtracting different wavelengths of light.

Now, let's consider the problem of mixing colors using only three oil paints. In this case, the three primary colors are typically red, yellow, and blue. These colors are called "primary" because they cannot be created by mixing other colors; they must be used as is.

To mix a new color using these three primary colors, we would need to combine different proportions of each primary color. However, there are an infinite number of possible combinations of red, yellow, and blue that we could use to create new colors. As a result, it is impossible to create a finite set of colors that includes all 3,200 colors using only three primary colors.

Furthermore, the human visual system is limited in its ability to perceive colors. Although we can see millions of different colors, there are actually many more colors that exist beyond our ability to perceive them. This means that even if we were able to mix all 3,200 colors using three primary colors, it is likely that many of these colors would be indistinguishable to us.

In conclusion, the math behind the primary colors myth is due to the principles of color theory and the limitations of the human visual system. It is simply not possible to create a finite set of colors that includes all 3,200 distinct colors using only three primary colors.

What about using three primaries and three secondaries?

It is not physically possible to mix all 3,200 colors using only six oil paints, because the number of colors that can be created by mixing a limited set of paints is limited by the number of unique combinations of those paints.

To understand this, we need to first understand the concept of a color space. A color space is a three-dimensional space in which all possible colors can be represented as a combination of three primary colors. There are many different color spaces that have been defined, each with its own set of primary colors.

Now, let's consider the problem of mixing colors using only six oil paints. In this case, the six oil paints would be the primary colors, and all other colors would be created by mixing different combinations of these primary colors.

The number of colors that can be created by mixing a set of primary colors is limited by the number of unique combinations of those colors. For example, if we had only two primary colors, we could create three unique combinations: pure primary color 1, pure primary color 2, and a mixture of primary colors 1 and 2. If we had three primary colors, we could create seven unique combinations: pure primary color 1, pure primary color 2, pure primary color 3, a mixture of primary colors 1 and 2, a mixture of primary colors 1 and 3, a mixture of primary colors 2 and 3, and a mixture of primary colors 1, 2, and 3.

As the number of primary colors increases, the number of unique combinations also increases, but it does so at a slower rate. For example, if we had four primary colors, we could create 15 unique combinations. If we had five primary colors, we could create 31 unique combinations. And if we had six primary colors, we could create 63 unique combinations.

As you can see, the number of unique combinations increases rapidly as the number of primary colors increases, but it still falls far short of the number of colors that the human eye can perceive. This is why it is not physically possible to mix all 3,200 colors using only six oil paints.

It is not possible to mix 3200 colors using only six tubes of oil paint, regardless of the color system being used. The number of colors that can be mixed from a given set of paint tubes is limited by the number of hues and shades available in those tubes.

For example, if you have six tubes of oil paint that each contain a different hue (e.g. red, yellow, green, blue, purple, and orange), you could potentially mix a large number of different colors by combining the different hues in various proportions. However, it is not possible to mix 3200 distinct colors using only six tubes of paint.

To achieve a greater range of colors, you would need to use a larger number of paint tubes, each containing a different hue and shade. A superior approach is to use a color system like the Munsell system, which allows you to specify colors using three coordinates: hue, chroma, and value. Using this system, you could mix the totality of colors possible by adjusting the proportions of the different hues, chroma values, and value values.

If you're ready to learn how to mix beautiful colors quickly, be able to mix colors that have eluded you in the past and most importantly, improve the colors in your paintings the full Digital Munsell Book of Color, including all the first chroma colors — the secret ingredients of French Academic painting — follow this link.