This file was downloaded from http://www.knitting-and.com/knitting/tips/pilling.htm
Drop 2 or 3 drops of glycerine in the water for a complete cycle in the washing machine, if it's wash by hand, only 1 drop, no more because it's greasy!
Glycerine gives back softness to the yarn and you can use in with fabrics too but! NEVER DRY BY MACHINE!!! It will stick and make all your efforts useless