Perhaps some similar strangeness to add to Steve's comment:
Sharpie markers have a dye that will bleed thru epoxy. I don't mean that the pigments in epoxy won't cover them up--I mean the Sharpie dye seems to migrate thru the epoxy. So you may "bleed" some kinds of dyes. In this case, the epoxy was 30 minute curing adhesive. It was not Zpoxy. I wouldn't expect it to behave differently, but it might.
I bought some pigments, but have been reluctant to try them. Not sure why, except I don't have a lot of confidence in my finishing abilities....
Dave