Alum block is, at least in the shavers world, an after-shave treatment. It comes in a couple of different forms; in block form (the Bloc Osma Natural Alum Block for example) somewhat like a bar of soap, or with a sort of applicator (like the RazoRock Alum Block) – think deodorant. In the end its the same product and serves the same function – to help you care for any minor nicks and cuts you my have caused yourself. The alum itself is made up of several chemicals – all natural – and it’s use dates back to Ancient Egyptians who also used it for its ability antiseptic and healing.
The why is rather simple – you care about your face. The more it stings when applying the Alum Block to your face the more you need it. It also acts as a good GAGE as to whether or not you need to adjust your shaving technique.
This is one of those areas, like many in classic wet shaving, where experimentation is needed. Some prefer to wet their face and then apply the block straight to their skin, others prefer to wet both the face and the block. There are those that leave the Alum on their face longer than others. And some who don’t rinse it off at all.
Regardless of what you prefer the application is the same. You rub the Alum block on your face, covering all areas. For cuts you want to pause and put some pressure on the cut until the bleeding stops.
One thing that is for sure is that you will more than likely experience some sting but it shouldn’t last long.