A sagging cap brim may not adhere to your head correctly and can feel loose or uncomfortable. The brim on a ball cap protects the face and eyes from the sun. If the brim has loosened it may shift on your head, becoming a nuisance. Stiffening the brim allows it to hug your forehead firmly and shield your face and eyes adequately. It also allows you to feel comfortable and stylish in your favorite hat.

Fill a tea kettle or pot with water and bring to a boil. Vent a lid over the pot so steam leaks out from one side.

Put oven mitts on your hands to protect them from steam burns. Hold the underside of the hat brim over the steam. Move the hat brim back and forth over the steam so the water vapor distributes evenly over the material. Remove the hat from the steam after 20 to 30 seconds.

Curl each end of the brim downward on the ball cap and lay it right side up on a hard surface.

Spray a light mist of starch over the top and underside of the cap brim. Allow the cap to cool before wearing.