Nike caps can be worn for fashion and can also be used to keep the sun out of your eyes on the golf course. As with any cap, though, your Nike cap can get filled with sweat and dirt, especially if you wear the hat outside or while exercising. It's important that you use care attempting to wash your Nike caps. Otherwise, the caps could lose their shape. Here is how to safely wash them.
Fill a sink with warm-to-hot water.
Add a fourth of a cup of liquid laundry detergent to the water. Use a detergent that has no bleach or a detergent with “bleach alternative” to avoid staining the cap.
Put the Nike cap into the sink. Allow the cap to soak for 30 minutes to an hour.
Scrub the Nike cap with the toothbrush. You can scrub the cap after removing it from the water or you can scrub it while in the water.
Rinse the Nike cap. Be sure to rinse thoroughly, as you don't want to leave any soap on the cap.
Allow the Nike cap to air dry by hanging it outside or placing it in front of a fan or window.