What is alum, and will it make someone’s mouth shrink, like in the cartoons?
Alum Herb Uses, Benefits, Cures, Side Effects, Nutrients
Padikaram / Alum Stone (Raw) / படிகாரம்
You can use alum to get a nice crystal as you wish.
The good news is it is available in online too.
You should test the product first, on a small area before using it for the first time.