Looking for alum substitute
I was going to make salt dough with my son as a summer project. The salt dough recipe called for alum and the book said I could find it in the baking section in any health food store. I went to look for it today but couldn't find it anywehre. It's a very small amount but I am not sure if leaving it out will make a big impact on the final product. The only thing I know about alum is that it's a preservative. Is there anything I can use to sub for this ingredient? I can't imagine making salt dough this difficult!