One of the great features of an American Hat Makers hat is the removable and washable Sweat Patch. When the Sweat Patch becomes saturated, just pull to remove it from the Velcro that holds it in place. Once removed, the Sweat Patch should be hand-washed using a mild detergent (like dishwashing liquid), then air-dried. Once dry, the Sweat Patch can be reattached via the Velcro. IMPORTANT: To prevent perspiration staining of the hat, Sweat Patches should be washed frequently (i.e., whenever the Sweat Patch becomes saturated).