Reshape your hat
If your hat is crushed or flattened, here are some tips to try- so don’t give up hope! This process, which involves steaming or stuffing the hat, is a really simple but effective way to get your hat looking fresh again. But always remember: never use an iron on felt, as it’ll singe the material.
Gently pop out any dents.
Stuff the entire hat with tissue paper.
Check the progress after a day, though it could take several days depending on the hat's style and the coarseness of the fabric. Remove the paper when the hat regains its shape.
A wet felt hat
If you are caught in the rain with your felt hat, turn out the sweatband to dry it and to provide a platform for the hat to slowly dry on. Gently push out the creases and dents to make the crown as rounded as possible. Never use a hair dryer as this will wrinkle and damage the hat. Once the hat is dry, gently reform the crease.
Steaming a felt or wool hat/cap for more re-shaping
Set a full kettle over a gas or electric range. Maintain the steam so it escapes the spout steadily but not forcefully.
Position the warped area over the steam (mind your hands!!!) for up to 30 seconds or until the fabric is evenly saturated.
Reshape the area with your fingers without overworking the fabric. Allow it to cool and stiffen.
Note: Any felt flowers or felt embellishments can also be gently steamed and reshaped. Do not iron them!
Steaming a straw hat
Straws can be reshaped as long as it's a good straw and doesn't have a wire brim.
Go ahead and follow the same instructions above to reshape your straw hat.
Reshaping a leather hat
Find something solid that looks like the shape of your hat. You can use bowls, balls and wig stands.
Place your misshapen hat on the object. This should be done as if you are placing it on your head, making sure the crown is pressed all the way down over your object. After doing this, you should notice the leather hat beginning to look more like its old, familiar form.
Brush any dirt or dust off of the hat.
Wet the areas of the hat that need to be reshaped.
Form the hat into the desired shape by forcefully creasing, pushing and pinching the leather with your hands. It’s vital to do this immediately after doing step 4, while the leather is at its wettest point.
Set your hat out to dry in a safe place. Wait until the hat is thoroughly dry before removing it from the object used to shape it.