Why elastic tolerates sun poorly
Short answer: Ultraviolet light breaks the bonds in elastane in the same way it fades dye. The thread turns brittle, loses its spring and can snap on the next stretch. That is why elastic clothing lasts longest when it is dried and stored in the shade.
Light goes after the bonds
The chemical bonds in elastane can be broken by ultraviolet light. Each bond is tiny, but they sit in long chains, and when enough are gone the thread cannot pull back. It happens gradually, so it is hard to notice while it goes on.
The same mechanism as with dyes
The mechanism is similar to colours fading in the sun. Light breaks down bonds in the dye, and in the same way it breaks down bonds in elastane. The difference is that a faded colour is visible, while a weakened elastic thread hides inside the yarn until the fabric is stretched.
The damage does not show at once
The outside of the fabric looks normal while the elastane inside has turned brittle. Only when you stretch it does it show that it no longer pulls back. A garment can seem faultless in the wardrobe and still fit loosely after a sunny summer. See bamboo shorts for men.
How the thread behaves after the damage
A thread weakened by light loses its spring and can snap when the fabric is stretched. Once it has snapped it cannot be repaired, and the area turns slack. It often happens first where the fabric stretches most, such as waistbands, armholes and edges that work all day.
Why elastic clothing is dried in the shade
Sun while drying is one of the hardest strains on elastane, because clothes hang for hours and the light hits the whole surface. Shade and air are far better. Hang clothes on a rack indoors, away from direct sun. See bamboo tank top for men and bamboo undershirt for men.
Swimwear is especially exposed
Swimwear is especially exposed, because sun, chlorine, salt and heat hit it at the same time. Each wears on the elastane alone, and together they do it faster. Rinse swimwear in cold, clean water after use and dry it in the shade, not on a hot beach.
Sun, heat and washing together
Sunlight is rarely the only strain. Clothes hanging in the sun are often warm too, and heat stresses elastane further. Add frequent hot washes and the thread loses spring faster. Wash at low temperature, choose a gentle programme and dry in open air so small strains do not pile up.
How to store your clothes
Store clothes in a drawer or on a shelf rather than on a windowsill or a chair in the sun. Do not leave them on a sunny balcony or in a car. That way the elastane does not sit in light for hours, and the fabric keeps its ability to pull back for longer.
What you can do in the summer months
Summer brings more sun, more sweat and more washing, and that strains elastic clothing. Rotate between several sets so each piece rests. Dry in the shade, wash at low temperature, and watch whether waistbands and edges still pull back. If they start to give way, that is a sign of wear.
Frequently asked questions
How long does the damage take
Weeks to months of daily sun, depending on how thin the fabric is. The thinner the thread, the faster light weakens it, so avoid direct sun when you can.
Is swimwear especially exposed
Yes. Sun, chlorine, salt and heat hit it all at once. Rinse swimwear in cold water after use and dry it in the shade to keep its shape.
Can you see the damage before the thread snaps
Rarely. Lost spring is the only sign, and it shows only when you stretch the fabric. If a waistband no longer pulls back as before, the elastane is giving up.
You can find the full range at Bamboo-Clothing.com.
