The steps for washing a cashmere sweater are a bit different than the regular washing instructions since cashmere is an incredibly unique material. Cashmere usually does best if hand washed at home.
Fill your sink or a large basin with some lukewarm water and then mix in a small amount of gentle detergent without adding any bleach. Next, press your sweater into the water until its fibers are completely wet. Softly swish the sweater around using your hands for several moments and then allow it to soak for 5 minutes.
After soaking it use cool water to rinse your sweater. Gently ball it up, while being careful not to twist or scrunch it, to get rid of excess water. Next, place the sweater flat on a dry towel on the floor and then roll it up to get even more water. After your sweater is just damp, lay it flat, reshape it, and allow it to dry.