This guide is for cashmere garment owners, hand-knitters who buy pure cashmere yarns by the cone, retailers stocking cashmere knitwear for the autumn-winter season, and warehouse operators who store cashmere yarn between spinning and knitting. If you own a single sweater or a hundred cones, the principles are the same: clean, fold, control humidity, inspect quarterly.

I write about cashmere at Consinee Group, China's largest cashmere yarn exporter and the source of a substantial fraction of the world's 100% cashmere cone supply — about 3,000 tons per year, or roughly one in five cashmere garments sold globally. We supply finished yarn to elite brands including Max Mara, Ralph Lauren, and Lululemon, and we hold GCS, GOTS, and GRS certifications on the relevant production lines. Because the same warehouse discipline that protects a 500-cone lot for six months in our Ningbo facility protects a five-sweater wardrobe in a Berlin apartment, I see the same failure modes in both.

Cashmere is a protein fibre — keratin, the same family as human hair. The cashmere fibre has a diameter of typically 14 to 19 microns, materially finer than the 19 to 24 microns of a fine merino wool, with a hollow medulla that traps air for thermal insulation. The same properties that make cashmere warm, soft, and luxurious also make it the preferred target of the common clothes moth (Tineola bisselliella) and the case-bearing clothes moth (Tinea pellionella), both of which feed on keratin and on the proteinaceous skin cells and body oils left on a garment after wear.

The fibre is also hygroscopic, so it tracks the humidity of its storage environment. Hold that humidity at 40–50% RH and the fibre is happy; hold it too high for too long and mildew takes hold; swing it wildly between hot dry and cold damp and the fibre's natural oils migrate and the surface blooms. Cashmere responds to those swings faster than a coarser wool, because the finer diameter and higher surface-area-to-mass ratio make every interaction more intense.

Before reaching for a repellent, it helps to know what you are repelling. There are four species whose larvae damage stored animal-fibre garments worldwide.

1. Tineola bisselliella, the common (webbing) clothes moth. The dominant species in temperate climates. The adult is a small, golden-yellow moth that does not feed; the larva is the destructive stage and feeds on keratin, body oils, and soiled fabric residue. Females lay 40 to 50 eggs over a few weeks, and the eggs hatch in 4 to 10 days at room temperature.
2. Tinea pellionella, the case-bearing clothes moth. Larvae construct a portable case out of fibre fragments and silk and carry it as they feed, which makes them more resistant to repellent volatiles than the webbing moth.
3. Tineola uterella, a tropical relative. More common in warm humid storage environments; same general biology.
4. Attagenus pellio, the fur beetle (technically a beetle, not a moth, but homeowners group it with clothes moths). Adults are small dark beetles; larvae attack fur, cashmere, and other protein fibres.

The repellents below — cedar, lavender, pheromone traps, low temperature — target different life stages of these species, which is why a layered defence is more reliable than any single product.

The single biggest mistake cashmere owners make is skipping the pre-storage wash. A garment that goes into a sealed drawer still carrying the last wear's body oils is, from a larva's perspective, dinner. Six steps before the drawer closes.

1. Inspect under natural light. Hold the garment up to a window and look for stains, sweat rings, food residue, and any sign of moth activity (irregular holes, fine webbing at the seams, sand-like frass at the folds). Spot-treat stains before washing.
2. Wash on a wool cycle at ≤ 30 °C with a pH-neutral cashmere shampoo. Avoid biological detergents and avoid fabric softener, because the cationic surfactant coats the fibre and reduces its natural moisture management.
3. Skip the high-RPM spin. Press water out by hand or use a 400 RPM final spin only. The mechanical agitation of a high-RPM spin felts the surface.
4. Dry flat on a clean towel, away from direct sunlight. Reshape the garment gently while damp. Do not hang — the weight of the water stretches the shoulders.
5. Confirm bone-dry before folding. A two-hour air-dry after the towel feels "almost dry" is the safe answer.
6. Fold along the natural drape line. Cashmere has a directional drape; folding along the seam line, not the centre of the back, reduces permanent creasing.

If you prefer dry cleaning, use a cleaner that uses a perchloroethylene-free, non-toxic solvent. Traditional perc cleaning is effective against moth eggs and larvae but can yellow white cashmere on long-term storage and leaves a residual solvent smell.

Three container options, ranked.

The single most common container mistake is a sealed plastic garment bag in an unheated attic or basement. The plastic keeps new moths out but also keeps any residual moisture in, and the temperature swings cause condensation that feeds both mildew and the surviving moth eggs.

The repellent question is where cashmere owners spend the most money on folklore. Here is the evidence-based read.

Cedar

Cedar heartwood volatiles — primarily cedrol and thujopsene in Cedrus atlantica and Juniperus virginiana (eastern red cedar, the cheaper and more common cedar in hangers and blocks) — repel clothes-moth adults at high concentration. The catch is that the volatiles evaporate, so after 6 to 12 months a cedar block in a closed container has lost much of its potency. Refresh by sanding the surface lightly with fine sandpaper every 6 to 12 months, or apply a cedar oil refresher. A sealed cedar ring on an open-wardrobe hanger is closer to a perfume than a repellent.

Lavender

Lavender (Lavandula angustifolia) contains linalool and linalyl acetate, both of which have documented repellent activity against moth adults at moderate concentration. Dried lavender flowers in a sachet are milder than cedar and need to be refreshed every 3 to 6 months. Lavender is a useful secondary repellent but should not be the only defence.

Mothballs (naphthalene / paradichlorobenzene)

Mothballs sold for clothing use contain either naphthalene or paradichlorobenzene, both registered pesticides under the US EPA Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and equivalent EU regulation. They off-gas toxic fumes, require strict ventilation, and are not safe around children, pets, or food. The US EPA Integrated Pest Management framework recommends non-chemical controls first, then lower-toxicity repellents, and only then — if at all — pesticide products in sealed containers. For a home cashmere wardrobe, mothballs are not appropriate.

Essential oils

Cedarwood oil, lavender oil, and a handful of other essential oils have documented repellent activity at high concentration. Commercial slow-release strip products work for 2 to 4 months per strip. Loose essential oil applied directly to the garment is not recommended — some oils are phototoxic on dyed fabric.

Pheromone traps

Pheromone traps target the webbing clothes moth (Tineola bisselliella) using a synthetic sex pheromone. They catch adult males and reduce the breeding population in a closed space. They are an excellent monitoring tool and a useful adjunct to other controls but are not a stand-alone defence.

Field note: In our Ningbo facility we use a layered defence — pre-storage vacuuming of cone surfaces, breathable PE-aluminium composite bags, silica-gel canisters at 30 to 60 g per cubic metre of storage volume, and quarterly inspections — rather than relying on any single repellent. The same layered approach works at home, because the failure modes (humidity drift, forgotten inspection cycles, faded repellent) are the same in both places.

Field note: In our Ningbo facility we use a layered defence — pre-storage vacuuming of cone surfaces, breathable PE-aluminium composite bags, silica-gel canisters at 30 to 60 g per cubic metre of storage volume, and quarterly inspections — rather than relying on any single repellent. The same layered approach works at home, because the failure modes (humidity drift, forgotten inspection cycles, faded repellent) are the same in both places.

The "put the cashmere in the freezer for 72 hours to kill moth eggs" trick has a basis in entomology: at –18 °C, clothes-moth eggs and larvae on the garment die within a few days. The protocol that works:

1. Wash and dry the garment first.
2. Place in a sealed plastic bag (so the freezer does not dry the fibre).
3. Freeze for 72 hours at –18 °C or colder.
4. Remove, let the garment return to room temperature inside the bag (to avoid condensation on the fibre).
5. Open the bag, refold, and put into the final storage container.

What the freezer does not do is prevent re-infestation. A garment that goes back into a moth-active wardrobe will be re-infested. The freezer is a quarantine step for a garment that may have been exposed, not a substitute for clean, humidity-controlled, sealed storage.

Two numbers determine whether your stored cashmere comes out of the box in October looking like it did in May.

Humidity: 40 to 50% RH. Moth eggs cannot hatch at sustained relative humidity below about 55% at room temperature, and mildew needs sustained humidity above about 65% to take hold. The narrow window between — 40 to 50% RH — is the safe envelope. A small dehumidifier in the closet, or a passive silica-gel canister in each storage container, is the simplest practical control. Replace or recharge the silica gel every 3 months during the storage season.

Temperature: 18 to 22 °C. Below 18 °C, moth egg development slows dramatically; below 12 °C it effectively stops, which is why an unheated but dry garage in a temperate winter is a better storage location than a heated but humid basement. Above 22 °C, fibre oils migrate and yellowing accelerates. A climate-controlled closet in a climate-controlled house is the practical answer for most owners.

The pre-storage discipline is the same for cones as for garments, with three small differences. Cone-wrapped cashmere yarn from our spinning lines is already clean (the spinning process includes a final wash and conditioning), but the cone surface can hold dust that attracts moths. Store cones in breathable cotton bags inside a rigid bin, with cedar blocks or lavender sachets, and inspect quarterly.

Avoid storing cones near a heat source — the wax on the fibre can migrate and the cone can yellow, and yellowing is not reversible by washing. Avoid storing cones in direct sunlight. If you are a hand-knitter who buys thick hand-knitting cashmere yarn by the cone, store the working cone in a breathable cotton bag between sessions and the spare cones in a rigid bin in a dark corner of the closet.

No container is perfect, no repellent is permanent, and no humidity control is fail-safe. The quarterly inspection is the safety net that catches what slips through. Every three months during the storage season:

• Open every container.
• Hold each garment up to natural light and look for new holes, webbing, or frass.
• Refold along a different line than the last fold to avoid permanent creasing.
• Re-treat cedar blocks by sanding the surface lightly.
• Replace or recharge silica-gel canisters.
• Air the storage area for 15 minutes to disrupt any moth pheromone trail.

For a multi-sweater wardrobe this takes 20 minutes; for a cone-lot warehouse it takes about an hour per 100 cones. The cost is trivial relative to the replacement cost of a moth-damaged garment or a written-off cone lot.

After twenty years of cashmere handling, these are the recurring failures.

1. Storing an unwashed garment. The single biggest cause of moth damage, because body oils and skin cells are the larva's food.
2. Sealing moisture inside a plastic bag. Traps the moisture that causes mildew and accelerates yellowing.
3. Storing in an unheated attic or basement. Temperature swings stress the fibre; uncontrolled humidity swings create the perfect environment for mildew and re-infestation.
4. Skipping the quarterly inspection. A small moth problem caught in May is a 20-minute fix; the same problem caught in October is a season's worth of damage.
5. Trusting one repellent forever. Cedar volatiles fade, lavender fades faster, and mothball fumes are toxic. A layered defence refreshed quarterly is the answer.

Storing cashmere correctly is not folklore — it is a layered discipline with a clear order of operations: clean, dry, fold, container, repellent, humidity, temperature, inspect. The four steps that deliver most of the benefit are washing before storage, holding 40 to 50% RH at 18 to 22 °C, using a breathable cotton container, and inspecting quarterly. The repellent choice is secondary; cedar or lavender, refreshed, plus a pheromone trap for monitoring, is the practical answer. Mothballs are a pesticide and belong in industrial storage, not in a home wardrobe.

For a hand-knitter who buys pure cashmere yarns or thick hand-knitting cones from us, the same workflow applies to the cones as to the finished garments — store the cones clean, in breathable bags, in a humidity-controlled closet, and inspect them when you take them out for the next project. If you want to discuss cashmere storage and mothproofing at a brand-inventory scale, our export team can structure the documentation for your warehouse SOP.