Is Epoxy Flammable? What You Need to Know Before You Use It

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Epoxy is used for everything from garage floor coatings to structural repairs to electronics potting. It comes in two parts: a resin and a hardener that react to form a rigid thermoset plastic. Its fire behavior changes significantly depending on whether it’s in liquid form or fully cured.

Liquid epoxy resin is flammable; cured epoxy is much less so. Uncured epoxy resin typically has a flash point between 300°F and 400°F (149°C to 204°C), which makes it a combustible liquid. The hardener component varies; some amine hardeners are more volatile and have lower flash points. Once cured, epoxy forms a cross linked thermoset polymer that is significantly harder to ignite, though it will still burn in a sustained fire.

Safety During Application

When working with liquid epoxy:

• Keep away from open flames, sparks, and heat sources
• Ventilate the work area, as epoxy vapors can accumulate
• The exothermic reaction during curing generates heat; large mixed batches can reach temperatures high enough to smoke or cause fires if left in a bucket. Pour thin layers rather than leaving a deep pool of mixed epoxy
• Hardener components can be corrosive; read the SDS for your specific product

Cured Epoxy in Fires

Fully cured epoxy is classified as a combustible solid. It won’t ignite from a spark or incidental heat, but it will burn in a sustained fire and contributes fuel load. Epoxy coatings on garage floors and epoxy bonded boat hulls contribute to fire spread and smoke production when a building or vessel is burning. The smoke from burning cured epoxy contains irritating and potentially toxic compounds.

High Temperature Epoxy

Specialty high temperature epoxies formulated for use near exhaust systems or industrial equipment are more fire resistant, but even these aren’t fireproof. They’re rated to maintain structural integrity up to certain temperatures (often 250–300°F / 121–149°C) rather than to resist combustion. For a related comparison, see our article on whether resin is flammable.

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