Subject: how to to make natural alum to be in cube like and soft in like a soap

Alum is extracted naturally from earth. Back in Malaysia we used a raw 
alum as a way to clear a muddy water and things like that. Another usage 
of it, we found out if we dip a raw alum into water and than rub it under 
armpit it can help to prevent from body odour.But the raw alum is a little 
bit rough and form this sharp edges once it dry. I just one to know, 
whether we can improvised by adding 'something' to this rwa alum to make 
it smoother but will keep it shape eg., cube like shape.
Thank you for anwering the question. I am looking forward for the answer. 

Re: how to to make natural alum to be in cube like and soft in like a soap