dats because dem too lazy to use Alum
alum , any one of a series of isomorphous double salts that are hydrated
sulfates
of a univalent cation (e.g., potassium, sodium, ammonium, cesium, or thallium)
and a trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or
titanium).
The name
alum commonly refers to potassium aluminum sulfate :cool:
http://www.mccormick.com/%7E/media/Images/Products/Product%20Details/Herbs%20and%20Spices/Spices%20A%20to%20Z/alum.ashx?w=225