In the last post I told you that zinc yellow, cobalt blue, and fuchsia produced the most vibrant colors of any of the possible combinations of 3 Premo primaries. At that point, you just had to take my word for it. In this post we will compare the three blues (turquoise, cobalt blue and ultramarine) mixed with each of the yellows (zinc yellow and cadmium yellow) to see if my observation holds true for the greens. (We will look at oranges and purples in future posts.)
In the image above, the blues are mixed with increasing amounts of zinc yellow. On my screen (and I hope on yours) the bottom two strips are more vibrant than the top one. Both of them contain clear, gem-like greens, but the bottom strip is a bit paler than the middle strip. It also lacks the “true” blue we see in middle strip. The differences are due to the fact that turquoise (seen in the bottom strip) is lighter than cobalt blue and it has strong yellow undertones. In a sense, turquoise is a blue that is already “part-way to green.” You might also notice that the turquoise strip turns to lime green before (with less added yellow) than the cobalt strip does. This is because turquoise is a “wimpy” blue compared to cobalt: It doesn’t have as much tinctorial power. Somewhat surprising is the fact that ultramarine is also wimpier than cobalt blue. Even though ultramarine is darker than cobalt, cobalt has more tinctorial power.
Now lets look at the top strip (reproduced below). Ultramarine has red undertones. This causes the greens to be deep and somewhat muddy.[This is not to say the greens aren’t beautiful, they are just not as pure (saturated) as the first set of greens.] Whenever we add a third primary to a mixture of the two others, we reduce the purity (“desaturate” it). The greens in this strip look somewhat “olivey” compared to those in the other strips. If we wanted to make a mixture of cobalt blue and zinc yellow “olivey,” all we would have to do is add a tiny amount of red to a yellow-green.
Now lets look at the same blues mixed with cadmium yellow. All of the greens are a bit muddy compared with those above. This is because cadmium yellow has red
undertones, so whenever we add cadmium yellow to blue we are adding a little red at the same time. When we add cadmium yellow to ultramarine blue we are adding yellow with some red in it to a blue that also has some red in it and the mixture is even more desaturated (below).
All of these colors are needed if we want to produce rich, sumptuous color combinations in our work. Lest you think I’m preferentially promoting saturated greens here are some desaturated greens I love.