One of the oldest and most natural shaving or skin products around is the humble alum block.

First used by the Egyptians, alum acts as an astringent (closing the pores and tightening the skin, much like witch hazel) and is a great antibacterial agent.

Rubbed over a wet, freshly-shaven face, the alum block makes a wonderful after shave. You get the same tingle you would from an alcohol-based after shave. You also get the same sting from nicks or irritated areas, so you’ll know how well your technique is progressing. The plus side is, the alum will tend to close up the smaller nicks, stopping bleeding.

Alum’s antibacterial properties mean it can be used as a natural deodorant. In fact, it’s believed that’s how it was first used. You’ll see alum deodorant marketed as ‘Crystal’ something or other. Because it’s pretty drying, commercial alum deodorant often has some aloe mixed in. Simply wet the block and rub briskly over your wet armpit. You will get great odor protection and it won’t stain clothes.

Alum shaving blocks can be found in Indian shops where it’s called ‘phatkari’. Due to Americans getting hip to a thousands-of-years-old practice, you can find ‘crystal’ alum deodorants lots of places, even Wal Mart. It will last you a long time; and you can help save the planet by cutting down on the packaging you won’t be throwing away, or aerosols you won’t be releasing into the atmosphere.

Alum is available in two main forms: potassium alum (or potash alum) and ammonium alum. As best I can make out, the potash alum is naturally occurring and the ammonium is grown or manufactured. They have different molecular structures, but both do the same thing as far as use on skin goes.

There is some concern out there that the ammonium alum might not be as safe as potassium alum due to fears of aluminum causing Alzheimer’s disease. Frankly I have no worries in this regard-using my standard measurement of danger, driving a car is a helluva lot more likely to kill me. But if you want to feel safer, go with the natural potash or potassium alum. This is what you’ll get at the Indian bazaars.

Whichever form you get, your face will thank you for a good rubbing with a block. And your coworkers will thank you for giving your pits a brisk once-over with it.