A thermosetting-resin-based coating that is capable of forming a substantially flame-resistant barrier upon being exposed to heat. The coating includes a thermoset resin, an acid catalyst having a pKa value of less than 2, a filler selected from glass, mica, talc, perlite, vermiculite and combinations thereof, and an organic-intumescent material. The thermoset coating is at least 75% of the total weight of the coating.