Baseball hats are a popular accessory, and often become stained from sweat. These sweat and salt stains can be removed with household items, to restore the look of the hat and eliminate unpleasant odours.
Dip a toothbrush into white vinegar, and rub it across the stained areas of the hat. Focus around the rim of the hat and the inside of the rim, as these areas tend to contact the most sweat.
Place the hat in the mould, and snap it into place. These plastic hat cages retain the shape of the hat. The mould must be secured to avoid it opening during the cleaning process.
Put the hat mould on the top rack of the dishwasher---do not place any other items to the dishwasher. Add a bleach-free dish detergent, and run a normal wash cycle.
Remove the mould and let it dry in a warm area, avoiding direct sunlight or harsh light that can shrink the hat.
Keep the hat in the mould for 24 hours. Remove the hat when it is dry, and check that the stains have been eliminated. If sweat stains are still present, repeat the process.