Alum is a chemical compound resulting from the union of two double hydrated salts. The sulfate most used for the formation of different types of alums is aluminum sulfate.
Most common form of the alum is one composed of two sulphates and water. All compounds that correspond to the empirical formula AB (SO4) 2 · 12H2O is considered an alum.
Alums form easily. Generally, aluminum sulphate is dissolved in water and then the sulfate of another element is added. The evaporation of water crystallizes the solution forming alum.
Most alums have an astringent effect and an acid taste. They are colorless, odorless and are generally in the form of white crystalline powder.
Potassium alum or potassium alum
One of the most well-known alums is potassium alum or potassium alum whose chemical formula is KAI (SO4) 2 and is formed naturally within several minerals such as, for example, calcantite, alunite and leucite. You can get alum crystals after being treated with sulfuric acid.
Potassium alum is one of the types of alums we use daily and is a potassium aluminum sulfate. It is found in the baking soda we use for cooking, for example. It is also used for water purification, in shaving products and skin treatment.
Potassium alum is also known in the form of a stone also called alum stone, alum crystal or alum mineral and is known as a natural deodorant.