Things You'll Need
Sink or large basin
Any item made from wool can shrink if it is exposed to water and friction. The amount of shrinkage depends on many factors, including the type of wool the item is made from, how tightly the item is woven or knitted, and how long it was exposed to water and friction. The most common cause of accidental felting -- the term used when a wool item shrinks in this way -- is improper laundering. While most felted items can be manipulated back into shape, extreme cases may be a lost cause.
Fill the sink or basin with warm water. Add 1/4 cup of wool soak.
Immerse the shrunken cap in the water and allow it to soak for 30 minutes.
Drain the sink. press gently on the cap to remove as much water as you can. Remove the cap and wrap it in a towel.
Stretch the cap back into shape using your hands. Soaked wool is very flexible, and it will be easy to stretch. Stretch the cap in both directions to increase the size.
Put the damp cap on your head to check the fit. Stretch the hat again if needed to increase the size. If you have accidentally stretched the cap too much, wet it down and try again.
These directions work for any animal fiber, including wool, mohair, alpaca and blends. Continue to stretch and shape the cap as it dries to maintain the new size. Use baby shampoo if you do not have wool wash.
Never put wool items into the washing machine or dryer.