At Papa Nui we do more tests than Bikini Atoll and whilst we don't measure Isotopes and Gama Rays we do lots to ensure you get the best from your cap.
We offer two sizes Medium which will cover 57-58cm and Large 59-60cm, however if you need to customise your fit we follow these methods;
To stretch, cold water soak, towel dry then place over knee to vigorously pull and rotate until desired sizing is achieved, normally 1-1.5cm. Wear until dry.
To shrink, sometimes a warm water soak is sufficient but if more shrinkage is desired observe the Papa's pot cap soup method. Boil cap for 10 minutes, towel dry and check size, if extra shrinkage is desired place in hot clothes dryer. Maximum shrinkage is usually 1- 1.5cm. These two tips will allow you to achieve extra sizing options outside of the medium and large size offering.