I only once used an alum bloc and it turned out to be a horrific mistake on my part. I stung me so badly I was sweating cold from the pain.
Does anyone have any more insight here as well? I am currently using an alum bloc and I love it. What I have found on the net though suggests that not only is the chemistry of potash alum different than that of aluminum, it is also to large to be absorbed by the body. Also, many natural deoderants utilize potassium or ammonium alum as opposed to the compendium of god knows what in regular anti-perspirants. Although, to be honest, with regards to the shaving soap and after shave balms, wet shaving on a general basis seems to go lighter on the heavier ingredients than that of Edge products etc.
As a healthcare provider, I would be more worried about ingesting forms of aluminum, as opposed to topical application. Im also pretty skeptical of the relationship....
I know my better half is always getting on me to avoid aluminum based anti perspirents all the time, but Tom's of Maine just doesn't stand a chance against me I tell you! But I've always thought of my alum block as very diffent. Only thing I really know is it STINGS like hell so I really use it.