So the salt crystal deodorants are potassium alum, which has been used for thousands of years for various things. It’s a naturally occurring rock, and people found it has mild antiseptic properties and stop small cuts from bleeding. It’s a popular aftershave for that reason, commonly available for purchase as an “alum block”.
When used as a deodorant, what’s actually happening is you’re creating a salty layer on your skin that bacteria can’t form on. (No idea how that works out in practice, I use actual deodorant lol). And indeed it is used in many actual deodorants for that exact purpose
HOWEVER, and I want to mention this not because you said anything wrong but because I have found it to be a source of confusion for many people, it is not the same as the aluminum salts used in antiperspirants. Namely aluminum zirconium and aluminum chlorohydrate. Different chemicals. They function by blocking your pores so the sweat doesn’t release in the first place.
Many people are concerned, whether or not the concerns are founded, that the antiperspirant aluminums are mired in health risks such as cancer. The alum blocks are not wrapped up in that in any way, other than the fact that they are also used in (and used alone as) deodorant. It’s an interesting little piece of nuance that doesn’t come up much due to the relative non-popularity of the alum blocks
What are the limitations? Not trying to start a fight, just wondering what’s on your mind that couldn’t be made in diorama form