Skip the dry cleaners. Though you might be accustomed to dry-cleaning wool and cashmere sweaters, the chemicals used can actually “strip the natural oils from the yarn, making it lose loft and luster over time.”
Do it yourself. Pre-treat the collar and underarms with an “enzyme-based stain solution.” Divide knits by color, add a “sulfate-free” cleanser to cold water, and soak for 30 minutes. Or use a newer-model washing machine with a “wool” or “hand-wash” setting, which are “almost as gentle.”
Dry right. Lay sweaters flat on a towel and roll—rather than wring—them out. Once damp, do not drape them over a chair, which can leave them misshapen. Instead opt for a sweater rack with flat mesh shelves. After they are completely dry, neatly fold them instead of hanging, which can stretch the sleeves.