Use a small amount of special wool detergent to wash your cashmere or you can also use a special cashmere shampoo. It is important to know that you should not use fabric softener when washing because this product could cause felting and alter the quality of your cashmere.
Soak your cashmere one by one in soapy water, pressing the material with your fingertips without twisting it or pulling on the knit. Do not let it soak. Then rinse your cashmere without twisting it or pulling on the knit. Also, be careful not to rinse it under running water. Press your sweater several times to remove the water. You can also wrap it in a towel, pressing gently to avoid damaging the cashmere fiber. This will allow the excess water to be absorbed by the towel.
Be sure to separate light colors from dark colors.