In theory, with one red, one yellow and one blue you should be able to mix every color you need, right? That's the premise behind the ubiquitous color wheel. Well, in practice there are a few problems. If your yellow is just a bit reddish, like Gamboge, you can't make an emerald green. That little bit of red will turn it toward brown. Or if your red is slightly purple, like Alizarine Crimson, how can you get a snazzy orange? The blue that comes along with the red will mix with yellow to make - guess what - brown, again. And so it goes. The
theory is about absolute primary colors, but the
reality is muddier than that. So, why bother limiting your palette at all? Why did the masters restrict their selection to only three or four possibilities? Why not just reach for the color that will give you the most accurate match?
The answer can be summed up in one word, "Cohesiveness". Painters usually want the elements of their pictures to fit together, and color is a too powerful a tool to overlook, whatever your goal happens to be.
In the watercolor below,
Doorway to the Palazzo Barbaro, by Anders Zorn, Only three colors have been used: black raw sienna, and permanent red. The bluish tints are simply the black thinned with water. The painting seems to portray an integrated light phenomenon and a believable space.
Now, take a look at this landscape:
Alright, I know I'm overstating the case, but I want you to see what the danger is in being a profligate colorist.
For homework, choose a set of primaries that appeals to you; one only of red, yellow and blue. Make a simple version of a color photo or a live scene, in which all the colors are made by mixing the three primaries you chose. here are a couple of potential images:
There will; be compromises in this process - some colors will not be possible to duplicate - but have faith. The result will be an overall cohesiveness that cannot be achieved with an extended palette. Have fun.