Mg(OH)2 will decompose when heated at right temperature and the heat absorbed by the reaction acts as a retardant by delaying

Flame Retardant Mechanism of Mg(OH)2 in 4 steps: 1. Mg(OH)2 will decompose when heated at right temperature and the heat absorbed by the reaction acts as a retardant by delaying ignition of the associated substance; 2. The water released dilutes combustible gases and inhibits oxygen from aiding the combustion; 3. MgO, the major decomposition product, is a high grade refractory, which could build up a protective layer against energy and oxygen ingress; 4. During the process, Mg(OH)2 will not produce any poisonous gas and the activated MgO will absorb the poisonous gas given off by the burning articles. Mg(OH)2 has been regarded as one of the best effective, non-toxic and environmentally friendly flame retardants.