Aluminium in cosmetics

Many antyperspiants contain Aluminium salts to reduce the flow of sweat from the skin. These salts work by dissolving in sweat and temporarily inhibit the flow of sweat to the surface of the skin. Aerosol and roll-on antiperspirants products typically contain ACH (aluminium chlorohydrate), whereas sticks, gels and other solid products are most likely to contain an Aluminium salts referred to as AZAG (aluminium zirconium tetrachlorohydrex glycine). AZAG is known to stain clothing with a yellowish tint when mixed with sweat. It can also cause a stiffening of the affected areas of clothing. These stains can be removed with the application of vinegar or a mild bleach. 

 

AlnCl(3n-m)OHm

 

ACH can be described as an inorganic polymer and can be charactersed by gel permeation chromatography, X-ray crystallography and Al-NMR. The aluminium salts interact with the keratin fibrils in the sweat ducts and form a physical plug that prevent sweat from reaching the skin's surface and they contract pores.
A small percentage of people are allergic to aluminium and may experience contact dermatitis when exposed to deodorants containing aluminium.