I’ve used sticks similar to
@MilkCrate - there are similar ones from Razorock (Italian Barber) and Shave Nation as well. I use actual alum block like Osma and Barbero. The only difference between what Tim uses and what i use is that the Crystal ones are made by compacting Alum powder under pressure and the ones I use are cut from an Alum block. They are the same compound and last the same amount of time - I find about 12-24 hours. The benefits to the Crystal is that it comes in a container similar to deodorant stick so it is easier to apply and the ones I use tend to last a little bit longer because they dissolve a little slower - I’ve used both and both are top notch.
What makes them so great are a few things - Deodorants are masking the odor - the ones I gave you links to also contain charcoal - so they also absorb the smell as well And these don’t have the metal content which is often is used in most mass produced deodorants/antiperspirants - but overall you are just masking the odor and they usually last 8-12 hours. They do this by adding fragrance in essence.
The alum on the other hand is actually killing the bacteria -it is an antiseptic so it removes the cause of the odor before they can emit the odor. it doesn’t have any scent or fragrance so your not competing with a cologne.It is an astringent as well. It is made up of only mineral salts - it is all natural.