Step 1: Spot clean extra-dirty areas by using more detergent diluted in water and scrubbing them with a toothbrush or other small brush.
Step 2: Soak the hat for a few hours and check the hat occasionally to see if any spots need more cleaning.
Step 3: Rinse the hat thoroughly with cool or warm water and gently pat dry with a towel.
Step 4: Reshape the hat by placing the cap (the part that sits directly on your head) on top of an upside-down coffee can, small bowl, or other container that mimics the shape of your head. Leave out to dry.