Why have my stretchy clothes gone baggy and lost their stretch?
Elastane is thermoplastic: heat softens it and it re-sets in whatever shape it was in. Two per cent of the garment carries all of the recovery, and once it has gone nothing puts it back.
- Difficulty
- beginner
- Time
- 10 min
- Read
- 4 min
Short answer
The stretch comes from a fine elastane core inside the yarn, usually only two to five per cent of the weight. Heat from a hot wash, a tumble dryer, a radiator or an iron softens the polymer and lets it re-set in the stretched position, so the garment bags at the knees and seat and never recovers. Chlorine, sun cream and body oils break the filaments outright. None of it is reversible — cool wash, air dry, never tumble.
Elastane is sold as Lycra, spandex and elastane depending on where the label was written, and it is the reason a huge share of modern clothing fits. It is also by a wide margin the most fragile fibre in the average wardrobe, and it fails silently — the garment looks identical and simply stops holding its shape.
Step by step
- Find where the elastane actually is.In most clothing it is a fine filament running down the core of a yarn, with cotton or polyester staple wound around it. The outer fibres do not stretch. Everything the garment does elastically is done by that core.
- Note the percentage on the label.Two to five per cent is typical in denim, shirts and trousers; up to twenty per cent or more in swimwear and sports leggings. A tiny percentage still governs the entire care regime.
- Understand the heat failure.Elastane is a segmented polyurethane. Its soft segments give the stretch and its hard segments hold the memory. Heat softens the hard segments so that whatever position the fibre is in becomes the new resting position. That is why a garment dried hot comes out permanently longer and looser.
- Recognise the symptoms.Bagging at the knees and seat that does not recover overnight; a waistband that no longer grips; leggings that slide down; jeans that fit at 8am and hang off you by lunch; a swimming costume that goes translucent.
- Understand the chemical failure.Chlorine, and the oils in sun cream and body lotion, attack elastane directly and break the filaments. The evidence is visible: tiny white or hair-like broken threads on the surface of swimwear and leggings, and a fabric that has gone slack and thin in patches.
- Take the prevention as absolute rules.Wash at 30 or cooler. Never tumble dry. Never dry on a radiator or a heated airer laid directly against the element. Never iron over the fabric. Rinse swimwear in cold fresh water within minutes of leaving the pool.
- Accept that it does not come back.There is no wash, soak or treatment that restores heat-set or chemically degraded elastane. A garment that has lost its stretch has lost it. The only useful response is to change how the next one is treated.
Tips
- Denim with elastane is a common casualty: a hot wash to freshen jeans destroys the fibre that made them fit, which is the real reason stretch jeans should be washed cold and rarely.
- The white hairs on old swimwear and leggings are broken elastane filaments, not pilling. There is nothing to shave off.
- Buy swimwear in a chlorine-resistant fabric — usually polyester or PBT rather than nylon and elastane — if you swim in a pool regularly. It lasts several times longer.
- Two identical garments, one air-dried and one tumble-dried, will visibly differ in fit within a couple of months. It is the single change that most extends the life of stretch clothing.
- Heated airers and radiators are as damaging as a dryer if the fabric lies against the hot surface. Dry stretch garments flat on a rack away from direct heat.
Common mistakes
- Tumble drying leggings and sports kit on low because low sounds safe — Even a low setting runs well above the temperature at which the polyurethane softens. Air dry, always.
- Ironing a shirt containing elastane at the cotton setting — The cotton wants three dots and the elastane melts long before that. Iron at the temperature of the most heat-sensitive fibre in the blend.
- Leaving a swimming costume in a bag after swimming — Chlorine keeps reacting in the damp fabric. Rinse in cold fresh water immediately, and wash properly at home.
- Buying stretch jeans a size down expecting them to hold — They will fit for an hour and then relax, and once the elastane is tired they relax permanently. Buy the size that fits when you sit down.
Questions people ask
Can baggy leggings be shrunk back in a hot wash?
No. A hot wash may shrink the cotton or polyester sheath very slightly, but it accelerates the destruction of the elastane that provides the recovery. You will make it worse.
How long should elastane last?
Well-treated, several years. Tumble dried every wash, often less than a year. Chlorinated regularly without rinsing, a matter of months.
Is elastane the same as Lycra and spandex?
Yes. Elastane is the generic European name, spandex the American one, and Lycra is a brand of elastane. They are the same class of fibre.
Why do my jeans stretch during the day and shrink back in the wash?
The cotton relaxes under body heat and movement while the elastane tries to pull it back. Washing lets the cotton return. As the elastane ages, less comes back each time until it stops entirely.