It is alum-based baking powder.
no
We have bulk supplies at https://aussie-alum-supplies.com.au
yes
Aluminum-based baking powder.
bubuk tawas
yes
I can't see how.
Alum is the common name for aluminum potassium sulfate or aluminum sulfate.
Put alum in some water allow it to dissolve. Then use it and wash your mouth for a week or two.
Alum is always crystal - its just that the powder is made of very small ones. The simple answer would be 'take a hammer to them'.
There are better products for cold sores than alum. However, you can buy alum in the spice department in most grocery stores.