I learned this trick many years ago from my girlfriend. My hubby loves to wear hats but they get dirty all the time. Luckily there’s an easy trick for how to wash a hat, without ruining their shape. All you need is some vinegar and a dishwasher.
If the hat(s) are really dirty, and stinky, pre-treat them by spraying them with vinegar. Let the vinegar soak for about 10 minutes. If there are really bad sweat stains you can remove them by sprinkling the stain with baking soda, spraying it with vinegar and then lightly scrubbing it with a toothbrush.
After the hat has been pre-treated for stains, place the hat on the top rack of the dishwasher. Use regular dishwasher detergent in the load, and run it through a full cycle.
After the dishwasher has finished it’s cycle remove the hats and insert a small bowl inside each hat and lay them on a flat surface to dry. It’s as simple as that! By pre-treating your hats and running them through the dishwasher your hats will be clean and smell fresh all over again!