Aluminum Chlorohydrate (ACH) is a complex inorganic salt that consists of complex basic aluminium chloride. ACH is a soluble aluminum complex. It is believed that ACH acts as an antiperspirant by precipitating inside the eccrine sweat glands to produce insoluble aluminium hydroxide, which then plugs the gland. There are many soluble aluminium salts that can be used as antiperspirants, but they differ only in the relative amounts of aluminium, chloride, and zirconium. Only ACH may be used in aerosol formulations. ACH is also desirable because it has a pH of about 4.5, which is less acidic than other aluminum salts and, therefore, does not irritate the skin or damage clothing as much as plain aluminum chloride. The empirical formula for ACH is Al2(OH)5Cl·2H2O. However, when dissolved, the basic unit of ACH is more closely given by Al13O4(OH)24(H2O) with seven disassociated Cl? ions[1].
A mild human skin irritant. See also ALUMINUM COMPOUNDS, CHLORIDES, and SODIUM HYDROXIDE. When heated to decomposition it emits toxic fumes of Cl-.
