A scientist working at the DuPont chemicals company discovered acrylic in 1941 while researching synthetic fibres. DuPont called it Orlon, but the new fabric didn't fulfil its commercial potential until the mid-1950s when sweaters for women became fashionable. Orlon proved to be the ideal fabric to make the garments at affordable prices. Today, a wide range of clothing is available in various types of acrylic fabric, including hats. If your favourite acrylic hat has become baggy, try restoring it to the right size by ignoring the washing instructions and subjecting it to a hot wash and tumble dry.
Set your washing machine to its highest temperature, which is 90 degrees Fahrenheit for most modern washing machines. There's no need to use powder for this process, unless your hat actually needs a wash.
Put your hat in the machine and start the washing cycle. Give the hat a full spin.
Remove the hat from the machine and put it in the tumble dryer at its highest heat for 30 minutes.
Repeat the process if you want to shrink the hat further.