Aluminum acetate is commonly used as a mordant in natural dyeing to help the dyes adhere to the fabric or fiber. Here are the steps to use aluminum acetate as a mordant:
 
Pre-wash your fabric or fiber to remove any dirt or oils that may interfere with the dyeing process.
Dissolve aluminum acetate in warm water. The recommended ratio is 10-15% of the weight of the fabric or fiber.
Add the dissolved aluminum acetate solution to a pot of hot water.
Add your pre-wetted fabric or fiber to the pot.
Heat the pot and maintain a temperature between 160-180°F (70-80°C) for at least an hour. You can also leave the fabric or fiber in the mordant solution overnight.
Remove the fabric or fiber from the mordant solution and rinse thoroughly with cool water.
Your fabric or fiber is now ready to be dyed.
 
Note: It's important to wear gloves and protective clothing when handling aluminum acetate, as it can be irritating to the skin and eyes.