Stretch fibres in women's underwear and what they do
Short answer: Stretch fibres such as elastane make underwear elastic, so it follows the body and returns to shape. They usually make up only a small part of the fabric but mean a lot for fit and comfort.
What stretch fibres are
Stretch fibres are elastic fibres that can be stretched to many times their length and draw together again. Elastane is the best known. They are blended into other fibres such as viscose or cotton so the fabric can give way. See the range of bamboo underwear for women and check the composition on each product.
Why underwear needs elasticity
Underwear has to follow the movements of the body without pulling or slipping. A fabric without elasticity would give way and stay that way when you move, which suits poorly something that sits close. That is why almost all modern underwear contains a small share of stretch fibre.
Natural fibres and stretch
Natural fibres and cellulose fibres such as cotton and viscose are not very elastic on their own. The stretch fibre makes sure the clothes can give way and come back. That means underwear of bamboo viscose almost always contains a little elastane, and the fabric is no longer entirely pure.
What you can read on the label
The label shows how large a share each fibre makes up, and the stretch fibre often appears as elastane or spandex. The more stretch, the more elastic and close the clothes can sit, but it is not the only factor. Knit and fabric weight also matter, so feel for yourself.
Fit and comfort
Stretch fibres help clothes sit close without chafing, but too much tightness can leave marks or feel restless. Choose a size that gives you room and try the underwear in the movement you need it for. See also bamboo panties if you want to compare fits.
How stretch fibres wear out
Elastic fibres can lose some of their elasticity over time, especially if the clothes are washed at high heat or dried hard. That can make the underwear loose and slack. Follow the care instructions and avoid fabric softener and high heat so the elasticity lasts longer.
Washing and care
Wash underwear gently according to the care label and turn it inside out. Use a wash bag and avoid the tumble dryer if you want the stretch fibres to last. Hang it to dry away from direct heat, and do not dry it on a radiator, where the elastic can be damaged.
When you need to choose
Consider how close you want the clothes to sit and what activity you use them for. For tops you can look at bamboo tops for women, where the composition also shows whether stretch is included. Read the label and choose by what suits you.
Frequently asked questions
Why is there elastane in underwear?
Elastane makes the fabric elastic so the underwear follows the body and returns to shape. Without it the fabric would give way and become slack.
How much elastane is there in underwear?
It varies from product to product. The label shows how large a share each fibre makes up, so check it for your underwear.
How do I keep the elasticity?
Wash gently, avoid high heat and the tumble dryer and hang the clothes to dry. Skip fabric softener if the label advises against it.
