Things You'll Need
Wool is a natural fabric, known for its warming and wicking properties. It is used to make nearly any article of clothing, but over time white wool will start to yellow. This wool needs to be lightened to look its best. Wool can also be lightened to give wardrobe a new look, although dark wool will not lighten significantly. Use either household hydrogen peroxide or bleach to lighten wool.
Using Hydrogen Peroxide
Handwash wool in cold water with a detergent designed for wool fabrics. Rinse the fabric thoroughly to remove all detergent residue.
Mix one part hydrogen peroxide with 10 parts of water and set the wool in the solution.
Leave the wool for 30 to 45 minutes, agitating it occasionally.
Wring out the wool and lay it on a flat surface to dry.
Wash the wool by hand, using a wool-specific detergent, and rinse thoroughly.
Fill a basin with 1 tsp. of chlorine bleach for every gallon of water.
Soak the fabric in the solution for 30 minutes, agitating it so it lightens evenly.
Rinse the fabric, wring it out and set it on a flat surface to dry.