Tilley hats are known for being easy to clean and care for. Most of the Tilley hat collection is designed for customers that lead adventurous lives--which can result in a fair amount of sweat and grime. Consequently, most Tilley hats are designed to be easy to wash on the go. Tilley hats can be made out of nylon, hemp, cotton, raffia or wool. No matter the material, the method for removing sweat stains is the same.

Saturate the stained portion of the hat with water.

Dip an old toothbrush into undiluted laundry detergent. Tap (don't scrub) the laundry detergent into the stained fabric. Treat both the top and underside of the fabric.

Set the hat out in the sun for a full afternoon. Check on the hat periodically and spray it with water to keep it wet.

Wash the hat. Launder it if the material will permit. If not, hand wash the hat in the sink.

Allow the Tilley hat to air dry.

Treat stubborn sweat stains in colored Tilley hats with vinegar. Add 2 tbsp. of vinegar to 1 cup of water. Soak the sweat-stained portion of the hat in this solution for half an hour. Rinse the solution out with cold water, hand wash or launder the hat and allow it to air dry.

Treat stubborn sweat stains on white or light-colored hats with hydrogen peroxide. Soak the sweat stained part of the Tilley hat in a solution that is one part hydrogen peroxide and one part water for half an hour. Rinse the hat thoroughly in cold water and allow it to air dry. If the stain is still there, use pure hydrogen peroxide to soak the hat again.

Treat sweat stains that still persists with a paste made or 1 tbsp. cream of tartar, three crushed, full-strength white aspirin and warm water. Dip your toothbrush in the stain and scrub it thoroughly. Scrubbing this way can damage the fabric of your hat, so it should only be done as a last resort. Allow the paste to sit for 1/2 hour. Rinse the paste away with warm water. Repeat until the stain is gone.