Medley Hills Farm Alum Granulated Powder (Food Grade) 1 lb Can be used for water treatment and purification Used in styptic pencils, and pain relief from stings and bites. Used for gardening since aluminum sulfate is acidic Add to soils to change the ph level Commonly used for hydrangeas to change the flower color (Blue/Pink) Can be used for dyeing and printing on cloth as a dye fixer.