The color of things is actually in the light that shines upon them. Light is the only source of color, and without light not even the faintest color exists
Scientists speak of certain “primary colors.” These are ones from which the greatest possible number of combinations can be made. The primary colors in light are red, blue and green. When red and blue light are combined, the result is a bluish-red called magenta. Mixing blue and green light produces a bluish-green called cyan. Red and green light go together to make yellow. All three combined give white light.
You will not get the same results, however, from mixing paints. This is because, in this instance, you are mixing pigments that reflect light rather than mixing lights of different colors. The primary colors for light are, therefore, not the same as those for paint. The three colors that result in the widest variety of combinations for paint are red, yellow and blue. Mixing two primary paint colors produces a “secondary color,” halfway between the two primaries used. Red and yellow give orange; yellow and blue make green; blue and red produce violet, or purple as some prefer to call it. Midway between the primary and secondary colors are “intermediate colors.” These are yellow-orange, red-orange, red-violet, blue-violet, blue-green and yellow-green.
Now that you have some understanding of how different colors are produced. To find out what dark brown and yellow makes mix equal parts or mix less of each to the other and you will get accurate results. For more information on this subject and others, please go to jw.p "Online Library" Also for free downloads, publications or read online.