Hat Cleaner

Steps

1. Check the hat’s construction. Modern baseball caps with plastic brims can be soaked. Vintage caps with cardboard brims should only be spot-cleaned. If in doubt, spot-clean.
2. For sweat stain pretreatment, mix 1 tablespoon of baking soda with 1 tablespoon of hydrogen peroxide to form a paste. Apply it to the inner sweatband and any visible stain lines. Let it sit for 10 minutes.
3. Fill a basin with warm (not hot) water and add 1 teaspoon of dish soap. Stir to create a sudsy solution.
4. Submerge the hat and let it soak for 15-20 minutes.
5. Use a soft bristle brush to gently scrub the sweatband, the bill, and any soiled areas on the crown. Scrub in small circles with light pressure.
6. Drain the soapy water and rinse the hat under cool running water until all soap is removed.
7. Reshape the crown and bill with your hands while the hat is still damp. Place the hat on a head-shaped form (a balloon, a balled-up towel, or an inverted bowl) to dry.
8. Let the hat air dry completely on the form. Do not use a dryer — heat shrinks the fabric and warps the bill.

Why It Works

Hat sweat stains are caused by the combination of salt, sebum (skin oil), and dead skin cells that accumulate on the inner sweatband. The salt crystallizes as sweat evaporates, forming white rings. The sebum oxidizes over time, turning yellowish-brown. Baking soda paste works on sweat stains because it dissolves the dried salt crystals (sodium chloride is soluble in alkaline solutions) and provides mild abrasion to lift the oxidized oils. Hydrogen peroxide bleaches the yellowed oxidized sebum through an oxidation reaction that breaks the conjugated double bonds in the oil molecules responsible for the yellow color. Dish soap provides surfactants that emulsify any remaining oils so they can be rinsed away. The soaking step allows the cleaning agents to penetrate the woven fabric of the sweatband, which is often multiple layers thick.

Tips

• Never put a hat in the dishwasher. This outdated trick uses water that is too hot and detergent that is too harsh, and it risks deforming the hat.
• Drying on a form is critical for maintaining shape. A small bowl or melon provides the right curve for most caps.
• For beanies and unstructured knit hats, you can machine wash on the gentle cycle inside a mesh laundry bag.
• Clean hats after every 5-10 wears, or more frequently if you wear them during exercise.
• If the hat’s color runs during soaking, the dye is not colorfast. Use cold water and reduce soaking time to 5 minutes.