Alum dates back to Ancient Rome, Ancient China, and Ancient Egypt. All of these civilizations knew the versatility and usefulness of this mineral. Our version is in a fine white powder form, but there are also different forms available such as a crystallized version. Get ready for the list of things Alum Powder can be used for: making playdough, toothpaste, deodorant, after shave, baking powder, fire extinguishers. WOWZA. Alum Powder keeps fruits and vegetables firm and crisp, so it is often referred to as pickling powder.