... - 3.5 and a specific gravity of 2.42. Alumina trihydrate is the largest volume flame retardant used in the world. On heating to ... 34% water. This irreversible process is, in part, what makes ATH an effective flame retardant. Aluminium hydroxide is also used as ... an adsorbent, emulsifier, ion exchanger, mordant, antacid, and filtering medium. It is also used in the manufacture of paper, ceramics ...