Underwear that keeps its shape after many washes

Short answer: Shape lasts when the fabric has a little elastane, when you wash at 40 degrees and when you avoid the tumble dryer. Heat is what ruins the shape most, and that is something you control.

Elastane keeps the fabric in place

A fabric with a small share of elastane pulls back after wear. Without it, fabric gradually gets bigger, because it stretches a little each day and does not recover. That is why old pieces often sit loosely. A soft bra also needs some elastane to keep its support, and you can see the styles in bamboo bras.

Heat damages fabric and elastic

Hot washes and the tumble dryer make the elastic thread stiff and brittle, and the fabric can shrink unevenly. This is often where a piece truly loses its shape. 40 degrees and air drying protect both fabric and elastic, from waistband to leg edge, including the soft styles in bamboo panties.

Rotation spreads the wear

If you use ten pieces instead of five, each one is washed half as often. That gives the elastic time to rest and spreads wear across more pieces. The result is that each piece keeps its shape longer. For men, a multipack of bamboo boxers is an easy way to get enough pieces into rotation.

The right dose of detergent

Too much detergent leaves residue that stiffens the fabric, and too little does not remove sweat. Follow the dosage on the pack for your water hardness and load size. Skip fabric softener, as it coats the fibres. The fabric may feel soft at first, but over time it loses its drape.

Do not overfill the machine

An overfilled machine rubs clothes against each other and the drum. That wears the surface and can cause pilling. Leave a hand's width free at the top of the drum. Wash underwear separately or with other light items, so heavy trousers with zips and buttons do not wear it down.

Use a laundry bag

A laundry bag stops bras and thin pieces catching on other clothes. Straps and hooks can otherwise tangle and stretch. Always fasten hooks before washing so they do not pull threads. It takes a moment longer, but pieces keep their shape and look better after many washes.

Air dry flat

Do not hang heavy wet pieces by the waistband, as the weight can stretch the elastic. Lay them flat on a drying rack or drape them over a rail. Bras dry best hung from the middle between the cups. Avoid direct sun and radiators, since direct heat has the same effect as the dryer.

When a piece is worn out

When the waistband no longer holds or the fabric has thinned, it is time to replace it. That happens to every piece sooner or later, whatever the care. Go through your drawer a couple of times a year and remove pieces that no longer fit as they should.

Frequently asked questions

Does bamboo viscose fade

The colour can get slightly lighter over time, but the fabric itself changes slowly. Wash at 40 degrees and turn pieces inside out to protect the colour.

Why does underwear get bigger over time

The fabric stretches a little with wear. Without elastane it does not fully recover, and heat can stiffen the elastic so it loses its spring.

Does a cold wash help

30 to 40 degrees is gentle and enough for most pieces. Colder than that does not properly remove sweat and skin residue, which can cause odour over time.