<P> The mixing of colored physical substances corresponds to subtractive color mixing, hence it corresponds to our intuition about mixing colors . To explain the mechanism, let us consider mixing red paint with yellow paint . The red paint is red because when the ambient light strikes it, the composition of the material is such that it absorbs all other colors in the visible spectrum except for red . The red light, not being absorbed, reflects off the paint and is what we see . This same mechanism describes the color of all material objects--note that light is not a material object--and so applies to the yellow paint as well . Making recourse to the figure above demonstrating additive color mixing, one sees that yellow light is composed of an (additive) mixture of red and green light . When we mix the two paints, the resulting substance has red paint and yellow paint . The yellow paint absorbs all colors except for red and green . However, the red paint will absorb the green reflected by the yellow paint . The red paint can be said to subtract the green from the yellow paint . The resulting paint reflects only red light and so appears red to our eyes . Note however that this description is theoretical and that the mixing of pigments does not correspond to ideal subtractive color mixing because some light from the subtracted color is still being reflected by one component of the original paint . This results in a darker and desaturated color compared to the color that would be achieved with ideal filters . </P> <P> By convention, the three primary colors in subtractive mixing are yellow, magenta and cyan; however, for a long time painters have used yellow, red and blue in place of these . In subtractive mixing of color, the absence of color is white and the presence of all three primary colors is black . The secondary colors are the same as the primary colors from additive mixing, and vice versa . This is not an accident . By mixing additive secondary colors subtractively one can reachieve the primary additive colors . Subtractive mixing is used to create a variety of colors when printing on paper by combining a small number of ink colors, and also when painting . Green is a part of mixing yellow and blue . Orange is a part of mixing red and yellow . Purple is a part of mixing blue and red . </P>

What colors do you combine to make yellow