Alcoa C-231 Aluminium trihydroxide Alcoa Flame and Smoke Retardants >> Aluminium trihydrate Pigments >> Titanium dioxide ADHESIVE Alcoa® white hydrated alumina, is aluminum trihydroxide, Al(OH)3, that is produced through special processing of alumina-bearing feedstocks and stringent process control systems. The result is an alumina trihydroxide of exceptional purity and whiteness. Although hydrated alumina is a dry powder, it contains a high proportion, approximately 35 percent by weight, of chemically combined water. The hydrate is a nonabrasive, low-density material with a Mohs’ hardness index of 2.5 - 3.5 and a specific gravity of 2.42 g/cc. White hydrates are used primarily in applications where color and the absence of impurities are critical. They are halogen-free making them excellent nontoxic flame retardant/smoke suppressant fillers for plastic compounds. Alcoa precipitates a highly pure gibbsite phase of alpha alumina trihydrate. The Alcoa proprietary white stream process is designed, through chemical and recrystallization processes, to achieve near 100 percent photovolt brightness and relatively uniform particles. Ground White Hydrate Intermediate and fine size grades are produced by grinding the precipitated grades to form C-231 (14 microns) and C-333 (7 microns). Grades C-231 and C-333 are ground versions of Grade C-33. They are used in polymer formulations, toothpastes, adhesives, coatings, paper, cosmetics, waxes and polishes. White, pure, halogen-free hydrated alumina. Used primarily in applications where color and the absence of impurities are critical. Used as flame retardant/smoke suppressant fillers for plastic compounds.