Hi, I have recently purchased some black polyester pigment from you and this appears to be causing me curing issues with my gel coat. My first application did not harden at all, and I assumed that I must have missed the MEKP addition in error! I had to remove with acetone, reapply release agent and retry, however I had exactly the same result. Again I removed with acetone and reapplied release agent.
I applied some GL50 gelcoat in another mold at the same time with some grey polyester pigment and this hardened quickly with no issues.
For my third attempt I used some white gel coat I had in stock and this hardened correctly with no issues.
I am assuming there is an issue with the black polyester pigment you have supplied?