Shavex alum bloc used as a deodorant

I do not know if this is the proper forum for my question or not,so I apologize if it is not.I wanted to start using my Shavex alum bloc for deodorant and get away from the chemicals in regular types of deodorant.I started to use my shavex under my arms when I got out of the shower and it was working great,but I started getting a red rash.Has anyone else had this happen to them? what is in the Shavex alum bloc or any other brand for that matter,that would cause irritation? I dont know why,if alum is a healthy natural product what could cause this to happen.I thank you for any info

Check what kind of Alum it is. There is Potassium and Ammonium. usually the Ammonium is what is used in the deodorant and Potassium is what is in shave products. I would imagine the Potassium might be too mild for deodorant use.

Shavex Alum is the only one I use for shaving each time. I love it.
I suspect your problem is this; your Shavex will form/leave a "grit", very fine, almost powdery residue on your face after you leave it there for 10 minutes or more. Try it one day, on your face. Leave it there, after applied heavy, then after 10 to 20 minutes, stroke & feel your face, you will feel it. This fine "grit" could be rubbing your underarms raw.

When I'm applying it to my face, it goes on heavy & sits for 5 minutes; then I damp a hand towel with cold water & "dab" the towel all over my face to remove the excess alum, then there is no "grit" left. Then my witch hazel is applied.