You might also be able to perform this step in a sink, though using a pot will give you greater control over the temperature of the water.
Do not allow the water to come to a boil. In addition to potentially causing burns, water that is too hot might cause the cap’s bill to warp and lose its structure.
If you don’t plan on reshaping the bill later, you can hold it out of the water entirely, wetting only the cap’s crown.
Soak the cap until the fabric of the crown begins to “billow” a bit; this is a sign that it has loosened up sufficiently to be refitted.
Drying a hat this way will likely take all day. For best results, heat the cap early in the day and then wear it as you go about your business. Hang the hat up by the bill overnight using a clothespin to prevent stretching or warping as it continues to dry.
Showering in a hat or pair of boots you wish to break in is a trick that has been used for a long time with great results.
If you decide to simply take a regular shower while wearing the cap, be sure not to get soap or shampoo on the hat as it soaks. Washing your cap should be performed separately with the right products. Let most of the water fall on the crown of the cap to avoid potentially ruining the bill.
Wearing the cap on a clear, warm day will allow it to dry most efficiently. If the weather outside is cold or rainy, do not wear the cap out. Instead, allow it to sit right-side-up under a fan or in front of an air conditioning vent and check on its progress periodically.
If you’re washing the cap by itself, make sure to set the washer to the smallest load setting so that the wash and rinse cycles don’t use too much water. Putting the cap in the washer with other clothes will cause pressure and friction to work on the cap, breaking it in better.
If you only need to shrink a polyester cap a little bit, you can remove the cap from the washing machine after the initial wash cycle.
If the polyester shrunk a little too much due to the heat from the wash, wearing it as it dries can stretch it out to an optimal fit.
Washing and drying a synthetic cap regularly will most likely cause it to shrink quite a bit more than a gentle soak or hand wash. If the hat shrinks too much, try putting it on while it’s still somewhat damp. The fibers should stretch out as the cap becomes worn in. Keep an eye on the hat as it dries. Synthetic materials have been known to scorch if exposed to heat for too long.
