How do you shrink a flat cap?

Answer 1

Put a couple litres of warm water and a small amount of washing powder (couple thimbles full) into a sink. Keeping the brim out of the water, wash the back of the cap working your way forward toward the front. Give the front and the lining a good wash near the forehead to get rid of the built up salt from sweat.

Douse the brim with a couple handfulls of water to get rid of the lint but just give it a light wash.

Hang it out to dry in a cool spot out of the sun by the brim so the water drops from the back.

The cap will come out looking new, but the brim will only be ~%80 crisp as it was new. Still it'll buy you some time to find another or extend the life of your favourite cap.

Answer 2

leave it in a airing cupboard/boiler room. for a few days and keep getting it out to make sure it has not shrunk to much try damping it with a sponge to help shrink it

this may not work for you but it did for me