Mixing a perfect gradient from blue to orange took a month. Keeping the value the same (the relative lightness/ darkness of each color) was a challenge, as well as discerning the subtle shifts in hue to create eight equal steps between the nine colors. Many small studies were done before each color was deemed correct. I mixed up a big batch of each at that point, and then painted the final result in several sizes.
all images copyright David Michael Slonim 2020