Although womens' wool sweaters are expensive, they can last several decades if cared for properly. Wool is a completely natural fabric that is sensitive to extreme heat, sunlight, strong detergents and stretching. Therefore, you need to carefully wash and dry wool sweaters by hand rather than using washing machines and heated dryers. In addition, care for your sweater after you wash it by storing it properly so it will last as long as possible. In general, you only need to wash a wool sweater once or twice per season unless you have gotten stains or strong odors on the sweater.
Set the sweater flat on a piece of cardboard, poster board or a large sheet of paper and smooth it out so it is in the shape that it most naturally goes into. Carefully trace the outline of the sweater onto the cardboard or paper with a pencil, being careful to not get any marks on the sweater itself. Cut out the shape of the sweater with a pair of scissors and write a description of the sweater on the stencil so you can reuse it next time you wash the sweater.
Fill a sink, large bucket or the basin of your washing machine with tepid water. Add a gentle detergent formulated for wool, such as Woolite, according to the directions on the package. Agitate the water with your hand to mix the detergent through it before putting the sweater in. Gently press the sweater down to work the water through it, but do not wring or stretch the sweater. Soak the sweater for about three minutes, continuing to gently squeeze it throughout the process, but avoiding wringing or stretching the sweater.
Pull the sweater out of the water and gently press it to remove as much water as possible. Never wring the sweater at this point. It is not a problem if the sweater remains quite wet. Run fresh water over the sweater, squeezing it to work the water through it until the water coming out when you squeeze the sweater is free of suds. Press the sweater together tightly to get out as much water as you can without wringing or twisting the sweater.
Place the sweater on a towel and roll the towel to sandwich the sweater between layers of the towel. Press down on the towel roll to get as much water as possible out of the sweater. Place the sweater on a clean, dry towel in an area in your home that is out of the way so the sweater can stay undisturbed there until it dries. Set the stencil on top of the sweater and press the sweater flat into the shape of the stencil. Because the fibers often clench up when wet, you need to use the stencil to get the sweater back into the correct shape. Leave the sweater in place until it is completely dry.
Fold the sweater for storage. Hanging it can stretch it out of shape, and if you absolutely must hang a wool sweater, use a padded hanger to minimize the damage. Store folded sweaters in muslin or canvas bags to allow for some air flow. If you use plastic containers or bags, leave them slightly open. If you are concerned about moths, place odorless mothballs or small satchels of cedar chips in the container to keep moths away.