To reshape a shrunken wool sweater, try soaking the garment in two tablespoons of hair cream rinse mixed with a gallon of cool water, then roll in a towel to remove excess water and clothespin to a pants stretcher or board. Stretch a bit by pulling seams gently, but firmly at the shoulders, sides, and neck.
To restore a shrunken wool sweater, dissolve one ounce of Borax in just enough hot water to dissolve it and add to one gallon of tepid water. Immerse sweater in this and gently pull into shape. Then rinse in one gallon of tepid water to which 2 tablespoons of vinegar have been added.
I have found the "hair Conditioner" method works well. I tried it with a very cheap bottle from the dollar store and it worked like a charm. The secret is to really let it soak and gently "pull" the fibres apart. I used more conditioner than water but haven't played around to see what ratio works best. (08/03/2010)