Cashmere and wool are two of the most luxurious and durable natural fibers available — when cared for properly, a quality cashmere sweater can last decades. The problem is that wool and cashmere fibers have a unique microscopic structure that makes them extremely sensitive to heat, agitation, and alkaline detergents. Even a single wash at the wrong temperature or in a regular washing machine can permanently shrink or felt a cashmere sweater, reducing it from a medium to what looks like a child's garment.

The science behind wool shrinkage comes from the fiber structure itself. Wool and cashmere fibers are covered in tiny scales. Under high heat and agitation, these scales interlock with each other and cannot be separated — this is called felting, and it is irreversible. The key to washing wool safely is eliminating both the heat and the agitation that cause felting.

Cold water is mandatory for washing cashmere and wool. Even lukewarm water can cause some degree of scale engagement if combined with agitation. Fill a clean basin or sink with cold water — as cold as your tap can deliver. Hot water is strictly off limits. This applies to machine washing and hand washing alike.

Hand washing is the gold standard for cashmere and fine wool garments. Fill a basin with cold water and add a small amount of wool-specific detergent — Eucalan, Soak, or Woolite Delicates are popular options. Submerge the garment and gently knead and squeeze the soapy water through the fabric. Do not rub, wring, or twist the garment. Allow it to soak for 10 to 15 minutes. To rinse, drain the basin and refill with clean cold water, gently squeezing the water through until no soap remains.

If machine washing is necessary for wool or cashmere, use only machines that have a dedicated wool or delicate cycle. This cycle uses reduced agitation and cold water. Place the garment in a mesh laundry bag before putting it in the machine for additional protection. Use a wool-safe detergent. Even on the delicate cycle, machine washing is riskier than hand washing for fine cashmere — reserve it for hardier wool garments.

Drying cashmere and wool incorrectly is as damaging as washing incorrectly. Never hang a wet wool or cashmere sweater — the weight of the water will stretch the fibers and distort the shape permanently. The correct method is to lay the garment flat on a clean dry towel, reshape it to its original dimensions with your hands, roll it up gently in the towel to absorb excess water, then unroll it and lay flat on a fresh dry surface to air dry. This can take 12 to 24 hours.

Pilling is the formation of small fiber balls on the surface of wool and cashmere caused by friction. It is a natural property of these fibers rather than a defect, but it can make garments look worn faster than they actually are. To reduce pilling, turn cashmere and wool garments inside out before washing and wearing, wash less frequently when possible, and use a fabric shaver (lint shaver) to remove pills from the surface when they appear. Pilling does not mean the garment is damaged — it can be restored to a clean appearance with a fabric shaver.

How often to wash cashmere and wool is an important question because over-washing accelerates wear. Wool and cashmere have natural antimicrobial properties and do not need to be washed as frequently as cotton. A cashmere sweater worn over a shirt can typically go five to seven wears between washes. Air the garment out between wears by hanging it in a well-ventilated space rather than putting it back in a drawer. Spot clean minor marks immediately rather than washing the whole garment.

Proper storage is critical for cashmere and wool, particularly during warmer months when moths can cause irreversible damage. Never hang cashmere or heavyweight wool sweaters — the weight stretches the shoulders over time. Fold and store flat in a drawer or on a shelf. For seasonal storage, clean the garments before storing (moths are attracted to natural oils and stains), and use cedar blocks or lavender sachets in storage areas as natural moth deterrents. Airtight bags or containers add extra protection for long-term storage.

For Northern Virginia residents who own cashmere, wool suits, or fine knitwear and prefer professional handling, Laundry Picked Up offers careful wash and fold service in Alexandria VA. We handle your preferences and laundry is washed separately from other customers on commercial equipment. For cashmere and structured wool, note the special handling request when scheduling your pickup and we will treat these items with the appropriate care. Schedule at laundrpickedup.com.