How I mix neutral colors
Gray color occurs in all kinds of paintings, it is important to master mixtures of gray color so you are not dependent on black or ready-mixed gray. In this text I will describe how I usually mix gray, because you have to mix.
Blue and orange
Blue is a complementary color to orange, if you mix two complementary colors with each other, the result should be black or gray. Orange color is unusual in most palettes, but brown color is common, brown is just an orange that is dull, a little dirty. So from a blending point of view, it’s the same thing, brown is just a dirty orange.
French ultramarine and cobalt blue are both slightly warm in tone (a bit reddish) and both become beautifully neutral together with all orange-brown, mix these blue with burnt sienna or burnt umbra for a beautiful gray color, it also works with red ocher or Quinacridone Burnt Orange. However, you should avoid the red-orange-brown colors like Indian red, different Maroon or Brown Madder as the mixture will be violet. Since both French ultramarine and cobalt blue are granulating colors, the colors will separate slightly. This is especially noticeable if you paint wet with a lot of liquid. Personally, I like that they behave that way while others, I understand, do not like it.
Phthalo blue (RS) and Prussian blue are both synthetic pigments, the first is fairly modern (1935) while the second is very old (1704). They are colder (greener) in color than the two previously mentioned. Both become greenish mixed with orange-brown colors. It really is not nice with green-toned shadow colors in a painting. Sometimes I use this mixture anyway, but add a little red color to remove the green tone.
There are brown colors that become neutral together with these blue colors, I myself usually use Transparent Pyrrol Orange from Daniel Smith or Perylene Maroon or Quinacridone Burnt Scarlet depending on my chosen palette for a particular painting. It is also possible to use Indian red or Venetian red.
Red and Green
There are only two green colors that are complementary colors to primary red: Phthalo green (preferably yellow tone) and viridian I use both from time to time. Not very much but they are still worth mentioning, Phthalo green yellow tone together with Quinacridone Rose becomes perfectly gray, completely neutral and intense. The same red color becomes lighter together with viridian and the pigments separate so it is harder to master but it still works.
Yellow and violet
The third primary color is yellow, its complementary color is blue-violet. There is such a big difference in perceived light intensity of these colors that mixtures are very difficult to achieve. It is a gray color mixture that I never use, but just because it is still possible, it is here. Feel free to try, but it takes a little skill to succeed.
If you mix two secondary colors, you get a very impure primary color as a result. You can take advantage of this by mixing two secondary colors, one or both of which are already unclear, e.g. A dirty green along with a clear violet. The result is a beautiful gray mixture that is a little bluish. I like this color mix a lot, it’s nice.
The most common way for me to mix neutral color is with blue and brown, different depending on the painting and color choice. French ultramarine and burnt sienna seem to be many’s favorite mix. When a green color is included in a painting, I usually use a cold red together with the green to make a gray color. I never use yellow and violet, it is too difficult to master. But violet + some dull green I sometimes use. Try it, you will be amazed at how easy it is to mix and how beautiful the result will be.