When you toss a baseball cap in the washing machine to clean it, it can get damaged and lose its shape. Fortunately, a dishwasher offers an alternative. The mild cleaning cycle of a dishwasher can clean your soiled caps without harming them in the process.
Pour your normal dishwasher detergent into the dishwasher.
Place a cap frame around the baseball hat. These frames are typically plastic and in the shape of a hat, allowing you to lock the hat inside of the frame.
Place the hat and frame into the dishwasher. You can wash the hat with or without dishes in the dishwasher, but avoid washing heavily soiled dishes so food residue doesn't stain the hat. Glasses or rinsed dishes will be fine in the dishwasher.
Turn on the dishwasher and run a normal wash cycle.
Allow the hat to air dry inside or out of the cap frame.