Wool jackets are expensive, and caring for them isn't always easy. Wool has to be washed carefully by hand to prevent the fabric from shrinking and becoming too small and tight to wear. If you throw a wool jacket into the washing machine or you wash it too carelessly, the wool may shrink. In some cases, a shrunken wool jacket is beyond repair. The fabric can shrink so tightly that it can't be restored to its former shape. But in most cases you can follow a few steps to resolve the problem and restore a wool jacket to its former size.
Fill a plastic tub or utility sink with lukewarm water. Add a dash of mild hair conditioner and detergent and let the products dissolve into the water.
Soak the wool jacket in the solution. This will loosen and relax the yarns in the fabric. Rinse gently, and drain the water from the sink or basin. Press the jacket against the sides of the tub or sink to remove as much excess water as possible. Do not twist or wring the jacket.
Lay the jacket flat on a clean, dry towel to absorb excess moisture. Lay another towel on top to blot more water from the jacket.
Gently pull the jacket to its former shape. Use a fabric tape measure to help you resize the jacket if you wish. The more you pull at the fabric, the thinner and more stretched it will become. Continue to stretch the jacket until it dries completely, or it may shrink again.