Pickling Alum, ammonium aluminum sulfate
Pickling alum is used in homemade pickles to make them firm and crisp plus add to the preservation.
Many home pickle recipes call for its use.
Even though they both go by the common name of Alum, Pickling Alum is a totally different chemical,(NH4)Al(SO4)2·12H2O, and will not assist in making natural dyes color fast.
Please do not confuse this with the Dyer's Alum, Potassium Aluminum Sulfate,KAl(SO4)2.
We also sell Dyer's Alum for mordanting fibers to make natural dyes color fast.
Pickling Alum, ammonium aluminum sulfate listed in:
Cooking and Baking