Trolling around and thinking about color, I found this article (thanks to Serena Fenton's Layers of Meaning ) by Mandy Southan, of the Guild of Silk Painters. She clearly and concisely summarizes information about the use of 6 "foundation" colors for mixing paints -- and dyes. It's instructive to fine-tune one's eyes to analyze the colors seen in photos, nature and other artist's work. What reds, greens, blues -- where and in what amount do you see the complement of a major color? (Look out the window, at your clothing, at the photos on my previous post.) As Southan writes,
"Some people find it very difficult initially to distinguish between each of the two types of red, yellow and blue. They can see that they are different but cannot see the 'hidden' colour in each. Blues seem to cause most problems, perhaps because the human eye is least sensitive to blue and most sensitive to red. I think that the more you work with colour, the easier it becomes to differentiate the colour bias in each and analyse the constituents of any colour you see and so be able to mix it confidently."