Alum stops the bleeding. Alum causes the proteins in the skin to contract (astringent effect), which closes wounds and stops bleeding.
Alum neutralizes the drying effect of soap residues on your skin. Shaving soaps are alkaline or basic, with a pH value between 7 and 14. Alum dissolved in water releases an acid with a pH value of 7 or lower. This explains the neutralizing effect on the already alkaline soap.
Alum is lightly disinfectant. This makes it effective against pimples and acne.
Alum closes your skin pores.
Alum soothes and repairs the skin. This prevents or reduces skin irritations.
Alum gives a refreshing and clean feeling after shaving.
Alum is suitable for all skin types; also sensitive skin.
Alum is odorless and therefore ideal to combine with other aftershave products.