Aluminium Hydroxide works as flame retardant by giving off one third of its weight as water at a temperature of about 200°C. This reaction is endothermic and cools he source of the fire. The water hinders the oxygen in the surrounding air to get access to the flammable gases created by pyrolysis. The aluminium oxide remains as an inert protection layer on the surface of the solid material.

ATH products provide effective flame redundancy by diluting the amount of fuel available to sustain combustion during fire by replacing part of the resin. Secondly, ATH contains 34.6% bound water that is released at high temperatures [beginning at 230°C (446°F)] providing a blanket effect, which limits the oxygen available for combustion. Additionally, metal hydrates such as ATH absorb heat from the combustion zone, which reduces the prospect of continued burning. Finally, ATH will produce a char during burning that results in further flame retardant protection and less smoke generation.