Colorant isn't part of the chemistry. Too much liquid colorant dilutes the resin-to-hardener reaction, leaving soft spots; manufacturers commonly cap additives around 6–10% of mixed weight. Mica is inert but past ~3% it can clump and leave dull patches. Always mix A and B thoroughly before adding color.
Avoid water-based paints and food coloring: water reacts with the hardener and causes cloudiness.