Is it possible to produce a full range of colors by mixing the basic colors in invisible black light chalk?
Unfortunately, it does not work out that way in actual drawing. That is why pastel artists have such a vast array of colors in their palettes. Some pigments are more concentrated than others, and some colors can only be achieved by mixing as many as three or more pigments. The problem becomes a question of whether the artist wants to take extra time to achieve a certain effect, or save time by having a color already on hand. In the long run, it is cheaper to have the color on hand, than to mix several colors as you are drawing. For instance, to make a purple, you can take a red and a blue. But if you want to get a pastel shade of purple, you may have to introduce a bit of green, but that in turn means you may have to start with a paler shade of red, which means you have to dilute the red with a non-fluorescent white pigment. The reason 17 colors are made in our line of fluorescent chalk, is that most artists have found these colors to be the most useful. They are not made to sell more
