How do I wash a garment made of blended fibres?

Most clothing sold today is a blend, and most care mistakes come from reading the percentages as a description of what the garment is rather than as a list of what will fail first. A jumper that is seventy per cent cotton is not a cotton jumper if the other thirty per cent contains anything delicate.

Step by step

1. Find the composition label, not the care label.They are usually different labels. The care label gives symbols; the composition label gives percentages. Both matter, and the composition label tells you why the care label says what it does — and lets you make a judgement when the care label is missing or has washed away.
2. Scan for elastane, spandex or Lycra first.Even at one or two per cent it governs everything: 30 degrees or cooler, no tumble drying, no radiator, no iron directly on the fabric. The elastane is what makes the garment fit, and heat kills it permanently.
3. Then scan for wool, cashmere, alpaca, mohair or silk.Any protein fibre in the blend means a wool or delicate cycle with a non-biological detergent, because enzymes digest protein regardless of what the rest of the garment is made of. Cool water and no rubbing.
4. Then scan for viscose, rayon, modal or bamboo.These lose much of their strength wet. Wash cool and gentle, use a low spin, never wring, and support the garment's weight when you lift it out.
5. If none of those are present, use the robust treatment.Cotton, linen, polyester and nylon in any combination will take a warm wash if the colour allows. The one constraint that remains is the iron: set it for the fibre with the lowest melting point, which will be the synthetic.
6. Handle the drying by the same rule.Tumble drying is decided by the weakest fibre, not the strongest. A cotton-polyester-elastane shirt is a no-dryer garment because of the elastane, not a yes-dryer garment because of the cotton.
7. Watch for differential shrinkage in structured garments.Where a blend is combined with a lining or with interfacing of a different fibre, the two shrink by different amounts and the garment puckers. That is one of the genuine reasons a lined garment says dry clean only.

Tips

• Common blends and what governs them: cotton with elastane is an elastane garment; wool with nylon is a wool garment; polyester with viscose is a viscose garment; linen with viscose is a viscose garment.
• Percentages are by weight, so a small percentage of a light, fine fibre can be a large proportion of the yarn structure. Never dismiss a small number.
• If the composition label has been cut out, the burn test on a single thread from a seam allowance will tell you the family, which is enough to choose a wash.
• Where two fibres in a blend want different things and neither is fragile — say cotton wanting hot and polyester wanting cool — go with the cooler, because nothing is gained by the hotter that a full detergent dose does not deliver.

Common mistakes

• Washing by the dominant fibre — Ninety-eight per cent cotton washed at 60 with a tumble dry destroys the two per cent elastane, and with it the fit of the garment.
• Assuming a wool blend is fine with biological detergent because it is mostly acrylic — The enzymes attack the wool component specifically, thinning it while the acrylic is untouched. The garment goes shapeless.
• Ironing a blend at the natural fibre setting — The synthetic in the blend melts, glazes and shines at a temperature the cotton is comfortable with. Set for the lowest melting point present.

Questions people ask