You may have an old baseball cap you wear all the time and can't live without out. Or perhaps you have vintage or collectible baseball caps that need to be preserved and restored. The cleaning process for old caps requires delicacy, with care being taken to preserve the baseball cap's color, texture and design.
Things You'll Need
Choose a mild detergent. Strong detergents may strip the color from the fabric. Don't use bleach or any product containing bleach; it may also strip color from your baseball cap.
Dip a corner of a clean washcloth in the detergent. Turn the baseball cap over so that the inside of the cap is facing upward. Rub the tip of the washcloth on a place on the cap that's not easily seen.
Wait. Allow the detergent to work its way into the fabric. Dip the other end of the washcloth into water and rub away the detergent spot on the cap. Allow the cap to dry, then examine it closely. If the color is fading or the fabric is deteriorating at all, then the detergent is too strong and isn't good for the cap. Try again with another type of detergent in a different hidden spot.
Rub the entire cap with the detergent from the washcloth. Rub very gently in small circles. Pay special attention to any obvious stains. Rinse the washcloth off and wipe away the detergent. Allow the cap to air-dry to prevent shrinkage or damage in a dryer. Don't put the cap outside to dry because the sun may cause the colors to fade.
Fill the sink with cool water if your cap is less fragile. Add detergent to the water and set the cap in the sink. Let it soak for a few minutes, then rub out tough spots with a clean washcloth. Allow the cap to air-dry indoors.