The epoxy system usually has a finish coating recommendation.

I use MAS and typically will add finish coats of Spar Captain's Varnish 3-4 days after my last coat of epoxy and have never had any issues.

Epoxy that has been properly mixed with hardener undergoes a chemical process that is not heavily dependent on the access to air. Temperature has a significant impact on dry time, but ultimately it should cure if properly mixed and undisturbed.

My results have been very consistent with the MAS epoxy system.

Eric M.