Is Rubber Flammable? Natural vs. Synthetic Rubber Explained

Rubber shows up everywhere: gloves, gaskets, hoses, shoe soles, and electrical insulation. Its fire behavior varies significantly depending on whether it’s natural or synthetic and how it’s been treated.

Rubber is flammable. Both natural rubber (from rubber trees) and most synthetic rubber compounds will catch fire and sustain combustion. Natural rubber ignites at around 500°F (260°C); synthetic rubber compounds vary widely depending on their formulation. Silicone rubber is an exception, as it’s far more fire resistant than other types.

Natural Rubber vs. Synthetic Rubber

Natural rubber is derived from the latex of rubber trees and consists primarily of polyisoprene. It burns steadily and produces black smoke. Vulcanized natural rubber (processed with sulfur for durability) burns at similar temperatures but releases sulfur dioxide in addition to carbon compounds, adding to the toxic smoke.

Synthetic rubber types, including neoprene, nitrile, styrene butadiene rubber (SBR), and EPDM, vary in flammability. Neoprene is relatively fire resistant compared to SBR; it has a higher ignition temperature and self extinguishing properties in some formulations. SBR (the most common rubber in tires) burns intensely once ignited.

Silicone Rubber: The Exception

Silicone rubber doesn’t behave like other rubbers when it comes to fire. It doesn’t burn easily, doesn’t drip flaming material, and produces less toxic smoke than most other rubbers. When silicone does combust at very high temperatures, it leaves a white silica residue rather than carbon char. This is why silicone is used in oven mitts, fire resistant gaskets, and aerospace seals.

Rubber Electrical Insulation

Old electrical wiring often uses rubber insulation. When rubber insulation becomes brittle and cracks, a sign of age, it creates a fire hazard. Exposed electrical conductors touching cracked rubber insulation can ignite it, which then spreads to surrounding materials. If you have older wiring with rubber insulation in your home, have it inspected by an electrician.

For a specific application of rubber combustion, see our in depth article on tire fires and what makes them so dangerous.