Potassium alum, also known as potassium aluminum sulfate, is a naturally occurring mineral that has been used for centuries as an astringent and antiseptic. It is different from aluminum in antiperspirants in a few ways:
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Potassium alum is a natural mineral, while aluminum is a synthetic chemical.
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Potassium alum is not absorbed by the skin, while aluminum compounds in antiperspirants are absorbed and can clog sweat ducts to reduce sweat production.
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Potassium alum works by forming a physical barrier on the surface of the skin, which can help to reduce sweat and odor, while aluminum compounds in antiperspirants work by temporarily blocking sweat glands.
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Potassium alum is generally considered to be safe for use on the skin, while concerns have been raised about the potential health risks associated with the use of aluminum-based antiperspirants, including the potential link to breast cancer and Alzheimer's disease.
It's worth noting that the FDA has classified antiperspirant as an over-the-counter drug and that the use of aluminum-based compounds in these products is considered safe when used as directed. However, if you have concerns or prefer not to use products with aluminum, potassium alum-based antiperspirants are an alternative to consider.

Gaia Guy has experimented with various natural organic deodorants. From baking soda and essential oil based ones that generally work well, but can melt and leave pretty serious oil residue on your clothes. To a solid crystal deodorant made from potassium alum, but the crystal deodorant didn't seem to work for very long.
Finally, taking the best of both. Turning the crystal deodorant into a powder like baking soda and pairing that with powerful herbs seems to have created a near perfect natural deodorant.
What's even better is that this is a real permaculture product in that we can stack functions with one product. It can be used as a deodorant, but also a foot deodorizer directly on your feet or sprinkled in your shoes. I have found it is even safe for other parts of the body too! As you can see in this fun little video.
@gaiaguy How I Apply Gaia Guy's Herbal Powder Deodorant #plasticfree GaiaGuy.com #zerowaste #herbal #powderdeodorant ♬ original sound - gaiaguy
Get a glass jar with your very own crystal powder deodorant!