When I was a student of Fine Arts, I earnt money by working as a shop assistant in an art material store. One day, a customer came in and asked for the fundamental colours in gouaches. I picked out tubes in black, yellow, blue, and red.
Wrong, he said.
And he explained to me that the fundamental colours are these: instead of red, it is magenta. Instead of blue, it is cyan. Yellow is alright. If you look at the blends in the rectangle fields of the 1st picture: Clear secondary colours. In the red-blue-yellow, 2nd picture, only the orange works. The green is very dull, and violet is a catastrophe.
During my jobs as a layouter, I was employed by print shops twice. In each case, I had a good impression of colour blending. At that time, it saved a lot of money to print in two or three colours instead of the full scale. So I collected some experience in colour processing.
In every print workshop, there were tins labelled "Rot nach DIN and EURO", this means: "Red by German and European industrial norms", and so in yellow and blue, of course. These define the fundamental print colours, in the case of red it is close to magenta.
I don't know the USA norms, but I'm sure they are similar.
How was this fundamental error about colours possible?
It seems to be a matter of history. The natural pigments that the painters used were never pure enough in colour to allow this experiment. It was not until about 1856 when chemical dyes were developed (anilin dyes) that mankind was able to reproduce colours that were visible in the spectral light and in some flowers and to turn them into a paintable substance and dying material. The "red-blue-yellow"-error was still kept up in the Bauhaus and has been impoisoning the colour vision of millions of school children who have learnt this in art lessons. Millions of elementary school teachers teach this still today.
I was grateful that this graphic designer opened my eyes to the true physical nature of colours. This has had an incredible impact on my choice of hues. I hope that my readers will feel encouraged to try it out themselves and have fun discovering a wider range of colours than before.
Of course, I was talking about print colours, the CMYK range. Here, they are reproduced by RBG colours. The differences are natural.