How to Read a Care Label — and Actually Follow It
May 21, 2026 — Mercer St.
Care labels are legally required on most garments sold in Japan, the EU, and the US. Most people ignore them. The result is garments that shrink, felt, fade, or lose their surface character faster than they should — often in the first few washes.
This note explains how to read the most common care symbols, why the instructions vary by material, and what happens structurally to a garment when care guidance is not followed.
In this note
- Why care labels exist — and why they differ by material
- The five care symbol categories and what each means
- Material-specific guidance: cotton, wool, cashmere, silk, alpaca
- What actually happens when you wash at the wrong temperature
- Practical notes on laundry bags, detergent, and drying
Why care labels differ by material
Different fibres have different structural properties — and different vulnerabilities. A cotton T-shirt can typically tolerate higher temperatures than a cashmere sweater because cotton is a plant fibre (cellulose) while cashmere is a protein fibre. Protein fibres — wool, cashmere, silk, and alpaca — are damaged by the same conditions that damage proteins: heat, alkalinity, and mechanical agitation.
This is not arbitrary caution. It reflects the actual chemistry of the fibre. Ignoring care guidance for protein fibres is the most common cause of irreversible garment damage.
Mercer Note
When in doubt, the care label is the authority. This note provides general guidance. Your specific garment may have different requirements depending on its construction, finish, and fibre blend. Always check the label first.
The five care symbol categories
1. Washing (the tub symbol)
The washing tub symbol indicates whether a garment can be washed in water, and if so, at what temperature and agitation level.
- Number inside the tub — maximum wash temperature in °C (e.g. 30, 40, 60)
- One bar under the tub — gentle cycle; reduced agitation and spin speed
- Two bars under the tub — very gentle cycle; minimum agitation
- Hand inside the tub — hand wash only; do not machine wash
- Tub with a cross through it — do not wash in water; dry clean only
For natural fibre garments — especially protein fibres — the temperature guidance is directly related to fibre stability. Washing cashmere at 60°C causes irreversible protein denaturation. The garment will not recover.
2. Bleaching (the triangle symbol)
- Empty triangle — bleaching permitted
- Triangle with two diagonal lines — only non-chlorine (oxygen) bleach permitted
- Triangle with a cross — do not bleach
Most natural fibre garments should not be bleached. Chlorine bleach degrades protein fibres and will permanently damage cashmere, wool, silk, and alpaca. It can also cause yellowing in white cotton over time.
3. Drying (the square symbol)
- Square with a circle inside — tumble dry permitted; dots inside the circle indicate temperature (one dot = low, two = medium, three = high)
- Square with a circle and a cross — do not tumble dry
- Square with a horizontal line — dry flat (do not hang)
- Square with a curved line at top — line dry (hang to dry)
- Square with three vertical lines — drip dry (hang wet)
Tumble drying protein fibres causes felting and shrinkage through a combination of heat and mechanical agitation. Even low-heat tumble drying can cause gradual damage to cashmere and wool. Drying flat — reshaping the garment and laying it horizontal — is the standard recommendation for most knitted protein fibre pieces.
4. Ironing (the iron symbol)
- Dots on the iron — maximum temperature (one dot = low/110°C, two = medium/150°C, three = high/200°C)
- Iron with a cross — do not iron
- Iron with lines through the steam holes — do not steam
Silk is heat-sensitive and should be ironed at low temperature, usually on the reverse side, if at all. Cashmere and fine wool can be gently steamed but should not be ironed directly. Cotton tolerates higher temperatures but should be ironed while slightly damp for best results.
5. Professional textile care (the circle symbol)
- Empty circle — dry clean
- Circle with a letter — specific dry cleaning solvents permitted (A = any, F = fluorocarbon, P = perchloroethylene)
- Circle with a cross — do not dry clean
- Circle with a W — professional wet cleaning permitted
Material-specific guidance
Cotton
Cotton is generally the most tolerant of the natural fibres. Most cotton garments can be machine washed, though the temperature and agitation level should match the label. Fine cotton — particularly interlock or smooth-knit cotton — benefits from a gentle cycle to preserve the surface character over time. Avoid tumble drying at high heat, which can cause dimensional shrinkage and surface degradation.
Wool
Standard wool felts and shrinks when exposed to heat and agitation together. Fine merino and superwash-treated wool are more tolerant, but the care label for the specific garment should be followed. Hand washing in cool water with a wool-specific detergent, then drying flat, is the standard approach for untreated fine wool. Never tumble dry.
Cashmere
Cashmere is a fine protein fibre that requires gentle handling. Hand wash in cool or lukewarm water (30°C maximum) with a detergent designed for protein fibres or wool. Do not wring, twist, or rub. Gently press excess water out, then reshape and dry flat, away from direct heat or sunlight. A fabric comb used occasionally on the surface will remove pills without damaging the fibre.
Mercer Note
Cashmere improves slightly with careful washing — the fibres settle and the surface softens with gentle, correct care. The garments that deteriorate quickly are usually those washed in the machine on a regular cycle, or dried with heat. The care is not complex; it just requires a little attention.
Silk
Silk is sensitive to heat, alkaline detergents, and mechanical agitation. Washable silk (where the label permits home washing) should be hand washed in cool water with a silk-specific or very gentle detergent. Roll in a towel to remove excess water — do not wring. Hang or lay flat to dry; do not tumble dry. Iron on the lowest setting on the reverse side if needed, or use a steamer held away from the fabric. Always follow the specific care label: some silk garments are dry clean only regardless of washable silk treatments.
Alpaca
Alpaca is similar to cashmere in its care requirements. Hand wash in cool water with a gentle detergent. Do not wring or twist. Dry flat, reshaping while damp. Alpaca has a natural halo — some surface fuzz — that is part of the fibre’s character, not a defect. Pilling is natural; a fabric comb will address it without damage.
What actually happens when you get it wrong
Understanding the mechanism helps make the guidance feel less arbitrary:
- Felting: Wool and cashmere fibres have a scale surface that, under heat and agitation, causes the fibres to interlock and compress irreversibly. The garment shrinks and hardens. This cannot be reversed.
- Protein denaturation: High heat causes the structural proteins in wool, cashmere, silk, and alpaca to unfold and denature — the same process that happens when you cook an egg. The change is permanent.
- Dye fade and bleed: High temperatures accelerate dye migration. Washing dark colours in hot water causes faster fading and can transfer dye to other garments.
- Surface degradation: Machine washing on a regular cycle creates friction that breaks down surface fibres over time, leading to pilling, loss of smooth character, and a worn appearance.
Most garment damage happens in the laundry. The garment itself is rarely the problem.
Practical notes
Laundry bags (mesh bags)
A thick mesh laundry bag significantly reduces mechanical friction during machine washing. For fine cotton garments that permit machine washing, a laundry bag on a gentle cycle is advisable. It is the standard recommendation for the Materica Black Interlock T-Shirt and other fine cotton pieces.
Detergent
Standard detergents are alkaline, which can damage protein fibres over time. For wool, cashmere, silk, and alpaca, use a detergent specifically formulated for protein fibres or a pH-neutral detergent. Avoid fabric softeners on fine knitwear — they coat the fibre surface and may affect the natural hand over time.
Drying
For most natural fibre knitwear: remove from water gently, support the weight of the garment, roll in a clean towel to press out excess moisture, then lay flat on a clean dry surface away from direct heat or sunlight. Reshape while damp. Do not hang knitwear — gravity will stretch the shoulders and distort the shape.
Storage
Store knitwear folded, not hung. Cedar blocks or lavender sachets help deter moths. Clean garments before storing — moths are attracted to body oils and food particles on fabric, not to clean fibre.
What to look for on your garment
- Find the care label — usually sewn into the side seam, back neck, or waistband
- Check the wash temperature symbol first
- Check whether tumble drying is permitted
- For protein fibres: assume hand wash cold unless the label specifically permits machine washing
- When in doubt: cool water, gentle detergent, dry flat
What this means for Mercer St.
Each Mercer St. product page notes the care requirements for that specific piece. Where the care label permits machine washing — as with some cotton pieces — this is noted. Where hand washing or dry cleaning is required, this is noted. The care guidance on the product page reflects the care label on the garment and is confirmed with the supplier before publishing.