Alumina Hydrate/ Alumina Hydroxide is a source of alumina in glazes. It is more correctly referred to as Aluminum Hydroxide, Al2O3.3H2O, but in studios and labs you will frequently hear it called alumina hydrate. It is a fine granular white powder, and because it is hydrated, it remains in suspension well when used in glazes. Small amounts decrease fluidity of glazes when they melt. In certain pink glazes, a small amount of alumina hydrate can enhance the color outcome.