A: Whether you’re a big leaguer or in little league, baseball caps are bound to get dirty during the course of the game. The combination of sweat, dirt, and grass will see to that.
The preferred method of care is simply to hand wash the cap with a mild dish detergent, rinse it, and let it air dry. Machine washing on a gentle cycle may be another option, but this tends to be rough on the brim of the hat. The brim usually contains cardboard and can bend, distort or even tear from the agitation of the machine.
The plastic, adjustable hooks on the back of the hat may also pose a problem since they tend to melt at higher drying temperatures. Some designers have replaced these plastic hooks with a metal sliding hook that does not melt during washing. A plastic cap form that fits in and around the cap to hold its shape may also be available. The form allows you to wash the cap in an ordinary dishwasher while preventing the brim from getting bent or distorted during the wash cycle. Be sure to choose a dishwashing detergent that does not contain chlorine bleach.
Before attempting to clean any cap, test for colorfastness by applying a small amount of detergent and water to an inconspicuous area, then blot it with a white cloth. If any traces of dye appear on the cloth it may not be safe to clean the cap.