"Subtractive" Color Mixing

	1. One way of mixing color is by combining color illumination or light. Mixing color light is called "additive" color mixing.
	2. The other method for color mixing is accomplished by mixing together media such as paint, inks, dyes, and other colorants. This is called "subtractive" color mixing. The two methods of mixing color do not result in the same results.

When any two or more colors of paint, markers, inks or dyes are mixed together to form a different color, this is called subtractive color mixing. The following information is about subtractive color mixing.

These color wheels were made using only the three colors of cyan magenta and yellow. Two of each color were mixed together to form the colors of red green and blue as shown.

Oil Paint - Acrylic Paint - Drawing Ink

One should have suitable sources of cyan, yellow and magenta paints or inks to do this. The color media should be as close to the proper hue and shade as possible. For example, various color media offered as "magenta" may not have the proper saturation or brightness to work effectively for the purpose of mixing colors as shown with these color wheels. Transparent media such as watercolor paint or ink work best. On the other hand, opaque paints that are usually made of finely crushed particles mixed with a binder do not always yield the desired results. When it comes to mixing opaque paints, it may be more practical to use ready-made reds, greens, blues, and browns, along with cyan, magenta, yellow, black and white.* For more about the use of black white red and blue in mixing colors, click here.

COLOR FILTERS

When one or more transparent color media are applied one over the other to form a different color, this is also subtractive mixing. Placing colored filters together is another example.

You can use a flashlight and filters to see how this works. Here is how magenta and yellow filters can make red light.

White light	Filters:	Yellow + Magenta = Red

The white illumination is actually a mixture of colors. The yellow filter stops (subtracts) the blue light from the flashlight beam. The magenta filter stops (subtracts) the green, leaving only red light to reach the wall.

LIGHT PLUS SURFACE DETERMINES COLOR

Before going further, keep in mind that it is the spectrum colors that are already combined in "white light" that allows for the colors that will be either absorbed or reflected. How the colors react to the surface of an object determines the color of that object.  

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EYE

This diagram shows what happens when we look at two blobs of paint. One blob is black. The other is white. The colors look different, because different amounts of the colors that form white light are absorbed (subtracted) out of it by the paint. We see only the light that is reflected. The color of the light that reaches our eyes determines what we see as the color of the object. The black paint subtracts all colors and no light is reflected. So it looks black. The white light does not subtract colors. It reflects all the colors. So it looks white. 

We think of color mixing as adding colors together. So why is the mixing of paints and inks called "subtractive" color mixing?

Paints, watercolors, markers, inks and other color media either absorb or reflect certain colors. Any color that is not absorbed from the light that shines on an object is reflected off the mixture. The color that is absorbed by the surface is said to be "subtracted" from the reflected light that we see.

Look at this diagram of how the blue color cyan mixes with the yellow color to form green. Keep in mind that the "white" sunlight is a mixture of colors.

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EYE

So even though we add colors together when we mix paint, the newly formed colors are caused by subtracting out colors from the reflected light. That's why this is called "subtractive" color mixing.

The "subtractive" primary colors of paint, ink and dyes

What is meant by primary colors?

The term primary colors usually means:

1. The colors that are the minimum number of colors that can be mixed to make the greatest number of other colors.

2. In their purest form, the three "subtractive" primary colors themselves cannot be made by mixing other colors.

What are the subtractive primary colors?

Magenta and Yellow make Red		Yellow and Cyan make Green
Cyan and Magenta make Blue

There is a direct link between the three primary colors for mixing paint and ink, and the three primary colors for mixing illumination. This link between cyan magenta and yellow and red blue and green has led to the inventions of color printing, color photography, and movies made with color film. This is based on the scientific process of color mixing. It gives us the color we expect to see in books, magazines, photos, and on video screens, tablets, phones and so on. However, such a scientific view of color mixing need not affect the choice of colors that a person may choose when creating a painting or when lighting a stage set for the theater. Museums are filled with masterpieces where the artists mixed together many colors that may have been quite different than the colors mentioned above.  Keep in mind that whatever the colors may be, the mixing together of color paint still utilizes the "subtractive" process of color mixing. The mixing of any color illumination utilizes the "additive" process of color mixing.

*For more about use of color mixing in art and painting, click on the following link.