Potassium aluminium sulfate dodecahydrate is a hydrate resulting from the the formal combination of anhydrous potassium aluminium sulfate with 12 mol eq. of water. It has a role as an astringent, a flame retardant and a mordant. It is a hydrate, an aluminium salt, a metal sulfate and a potassium salt. It contains an aluminium(3+) and a potassium aluminium sulfate.