Alum block acts as an aftershave and deodorizer
An alum block is a crystal-like stone that is moistened with cold water and gently rubbed over the shaved area to act as an antiseptic and to combat razor burn. It can also help to stop bleeding from small nicks and cuts.
An Alum Block is an essential for any man's grooming kit. It can be used as an astringent to sooth irritation, a coagulant to take care of any razor related injuries. It can also be used as a deodorant due to its antiperspirant and anti-bacterial properties.
And if all that wasn't enough, in the 1950's it was used as an alternative to hair pomade and if applied to wet hair, once dry, could be relied upon to keep a quiff standing tall for the whole day.