When going to art school, we were taught that most black paints are composed of carbon. Therefore, when mixing black with colors or white, it tends to muddy up the paints.

So I asked myself, if I used lines, and made them black to color to black to color side by side, how that will effect the painting. I had already shown that if the lines are close enough together, each separate color will effect the one next to it, creating the illusion of a new color. 

These lines did not get painted close enough to make that happen. But if you stand back, the illusion will work. Also, It will no longer muddy the other paints anymore.

The black will not muddy up the colors. The colors will still stay fresh looking. But there is a change.