Alum, or potassium alum, is used in a wide variety of skin care products due to its natural astringent or skin tightening properties. It can be found as an ingredient in cleansers, moisturizers and wrinkle creams and leaves a tingling sensation on the skin.
Potassium alum, also called potassium aluminum sulfate, is a naturally occurring mineral salt known as kalunite in its rock form. It is found in areas where potassium- and sulfide-bearing minerals weather and oxidize.
Alum is considered safe for use as a cosmetic and drug astringent, with a low level of overall risk associated with its use. There is a moderate concern of non-reproductive organ toxicity and a low concern about environmental toxicity.
In addition to its astringent properties, potassium alum is also a natural antiseptic and hypoallergenic. This allows for its widespread use in the cosmetic field:
- It is ideal as an aftershave to clean any nicks and cuts and tighten skin; it also helps to remove razor bumps.
- It works as a deodorant that kills odor-causing bacteria for 24 hours
Alum as a deodorant is often called a crystal deodorant, due to the fact that potassium alum in raw form appears as a colorless crystal, similar to quartz. It may also be used in its powdered form.