When paints are mixed together each absorbs certain wavelengths of light. The color that is not reflected is what we see. For instance, if red wavelengths are absorbed, yet blue and green wavelengths are reflected, then we see that color as blue-green.
One thing to remember about subtractive color mixtures is that the base is always white. There are two types of subtractive mixtures. Simple and Complex.
Printing inks, drawing inks, transparent water colors and color photography are examples of simple subtractive mixtures. With inks and water colors the light passes through a thin layer of color, bounces off the white paper and back through the layer of color to the eye. The standard colors in inkjet printers allow for a wide range of colors through this process. The magenta ink reflects both red and blue. The yellow ink reflects red and green, the cyan ink reflects green and blue. You may have noticed that the three primary colors are being reflected. The black ink makes the images and blacks sharper. The white paper provides the base.
Opaque pigments, such as paints, mix in a much more complex way. Painters will often use a standard selection of colors that can be mixed to create any color. This is where the primary colors come into play, though it may not be how you think. a painter’s palette will have two reds, two blues and two yellows. One of which is a warm color and the other is a cool color. Add in some black and some white and you are good to go. The reason for the warm and cool colors is because, while yellow and blue make green, a warm yellow is needed to make a grey blue. The red in the warm yellow helps absorb some of those green wavelengths and create a more neutral color.
The colors typically used are:
- Cadmium Red Light (warm red)
- Alizarin Crimson (cool red)
- Cadmium Yellow Light (cool yellow)
- Indian Yellow (warm yellow)
- Ultramarine Blue (warm blue)
- Cobalt blue (cool blue)
- Titanium White (or zinc)
- Ivory Black