The 8 Best Alum Blocks

If you want one block that does the job and travels well, the Gentleman Jon Alum Block is the safe choice. It's a big, flat slab of potassium alum that lives in a snap-shut plastic case, so it stays dry on the road. Wet it after shaving, glide it over your face, then rinse with cold water. It helps tiny nicks close and calms razor burn. It stings on fresh cuts, and it can crack if dropped on tile.

French barbers have reached for Bloc Osma since 1957, and the carton still says it's made in France from potassium alum. Shaving forums have long favored it as a solid block that wears down slowly instead of crumbling, so one can last a long time. There's no case, only a cardboard box, so give it a dry dish by the sink. It's on the small side, and it can shatter if it slips out of wet hands.

Proraso, the Italian brand known for its menthol shaving creams, makes the Proraso Post-Shave Stone from potassium alum. Its directions are clear: wet the stone, rub it over freshly shaved skin for up to half a minute, rinse, then follow with balm. That last step matters, because alum left on the face can dry it out. The chunky shape fills the hand well. It comes in a cardboard sleeve, not a case, so travel takes a little planning.

For shavers who also want an unscented deodorant, the G.B.S Alum Block covers both jobs. It comes in a clear hinged case, and the maker says one block lasts close to a year of regular use. Rub it over the face after a shave or under damp arms after a shower. One caution: the seller calls it aluminum free, but alum is itself an aluminum salt. It's free only of the compounds used in antiperspirants.

Made for gifting, the Muhle Alum Block is a round, polished stone tied with a ribbon and packed in a gift box with no plastic. Muhle, a German maker of razors and shaving brushes, means the ribbon for hanging the stone to dry, which keeps it out of puddles that turn alum soft and chalky. It does the same work as any good block, closing tiny nicks. You pay a lot for the presentation, and stock runs thin.

Made in Thailand, the Vital Green Alum Block is a plain potassium alum stone with a jute cord through it and a small jute bag to keep it in. It costs little, and it works as an unscented underarm deodorant as well as an aftershave. The maker suggests holding it on damp skin for several seconds, then rinsing. The block is small for a full face, and some find it leaves faint white marks on dark clothing.

A stick is handier than a block for dabbing one cut, and the Omega Alum Stick is shaped for that job. Its rounded top reaches the corner of the mouth or the spot under the nose without coating your whole face. It comes from Omega, the Italian shaving brush maker, and it slips into a toiletry bag. Expect a brief sting on a fresh nick. It's small, so it suits spot use better than covering a whole shaved area.

Anyone after a fragrance-free deodorant rather than an aftershave should look at the Natural Elephant Alum Stone. It's a crystal stick that sits in a push-up holder, so your fingers stay dry. Run it over damp skin right after a shower and let it dry before dressing. It keeps odor down for many people, but it doesn't stop sweat the way an antiperspirant does, so it may not be enough on hot days.