We can create a very simple formula from what was covered in the previous segment on color mixing, that will tell us whether we will end up with a dull (tertiary – three primary colors) or more pure color (secondary – two primary colors) from the mixture of two pigments.
If we mix French Ultramarine and Alizarin Crimson we get the following:
French Ultramarine + Alizarin Crimson = (B + r) + (R + b) = B + R = Clean mix
If on the other hand we mix French Ultramarine and Cad Red the result is:
French Ultramarine + Cadmium Red = (B + r) + (R + y) = B + R + y = Dull mix
It is the addition of this tiny bit of yellow in the mixture (the third primary color) which results in a more subdued purple, than the French Ultramarine and Alizarin Crimson mix. When looking at color mixtures I am leaving out any effect due to the relative transparency or opacity of the particular pigment.
Why is the color mixing formula important?
There are a number of key reasons why this is import.
Firstly, if you cannot predict just what color you will end up with when you mix two pigments together it will leave you a little uncertain and this will impact your work.
The second reason comes from the knowledge that the further away an object appears from you in a landscape then the duller the colors look due to the effect of atmosphere between you and the object you are viewing. Hence, by using this knowledge of color mixing you can easily mix duller paint combinations to correctly place your objects in the various landscape planes e.g. distant, middle distance and foreground.
Now obviously, one can learn which colors mixtures of your various pigments will produce by trial and error, but hopefully with this knowledge you will be able to take out the trial and error and much more quickly learn how to mix clean and pure or dull and grey colors at will.
It also means then you have a tool to better judge whether the addition of a new pigment to your pallet will add to the range of colors you can currently mix.
Time spent really looking at your pigments and analyzing just what their component colors are will save you a lot of confusion and frustration later on. It will also boost your confidence while painting and this will show through in your work.
By the way, pigments with the same name but from different manufacturers do not necessarily have the same component colors. For this reason the examples in this article only relate to Winsor and Newton artists quality watercolor paints. I had a student trying to mix a particular dull dark green color for which I used Raw Umber as a component it is a yellowish brown pigment with a very slight greenish tinge, but the brand of Raw Umber my student was using was more of a red brown in color so no wonder her green mixes leaned further towards the red than mine.
Here are a number of other mix formulas for your reference:
Cerulean Blue + Aureolin = (B + y) + (Y + b) = B + Y = Bright Mix
French Ultramarine + Aureolin = (B + r) + (Y + B) = B + Y + r = Dull Mix
In the final section we will look at the earth colors and see how the watercolor mixing formula applies to them.
Continue to: The Earth watercolors and color mixing