If your beanie is too big, whether because of a knitting or crocheting miscalculation or because it stretched, you can shrink it back to size with hot water. If your beanie is 100-percent cotton, you can shrink it with a trip through the washer and dryer, but if it's 100-percent wool, you will need to felt the fibers. Felting is the result of exposing animal fibers to heat and agitation, then shocking them in cold water.
Things You'll Need
Liquid dish soap
Fill a large cooking pot half full of water and add five drops of liquid dish soap.
Put the pot on the stove and bring the water to a boil.
Reduce the heat to a simmer and drop the beanie in the water.
Stir the water with a wooden spoon, agitating the beanie. Put on a pair of rubber gloves to protect your hands and lift the beanie out of the water. Plunge the beanie into a sink full of cold water and scrub the fibers together. Add a drop of dish soap directly onto the wool to make suds, which will make scrubbing easier. You will see the fibers start to felt together — the stitches will become harder to see, and the yarn will start to look fuzzy.
Return the beanie to the hot water and stir it some more. Repeat steps 4 and 5 until the beanie has shrunk to your satisfaction.