It happens to the best of us. We are working our way through a fresh load of clean laundry, untangling the slightly damp pile of T-shirts and socks to hang each garment out to dry, when among the twisted cotton jersey, we see the sleeve or cuff of something that absolutely should not have been washed in the machine.
We pull it from the pile, hold it with two hands in front of us and assess the damage: how much smaller did the combination of heat, moisture and movement make it?
Unfortunately, there is no sure way to reverse shrinkage but there are a few things worth knowing that may help avoid disaster in the future.
Things shrink because of the way the fabric is structured
According to Rebecca van Amber, a textile scientist and senior lecturer in the fashion and textiles department at RMIT University, almost all fabrics shrink because they are manufactured under tension. When yarns are run through machines and made into fabric, they’re pulled taut, regardless of whether it’s a woven or knitted fabric, like a T-shirt.
“When we wash the fabric, the water acts like a lubricant and allows the yarn to relax and sometimes it relaxes to the point of not being under tension any more,” Van Amber says. This causes shrinkage because the yarns ultimately retract and become shorter.
She says this applies across different materials because shrinkage has “less to do with the fibre and more to do with the type of structure it’s made into”.
Different fibres, different rules
Wool items shrink because there are scales on the surface of the wool that react to the combination of heat, moisture and agitation in a washing machine. Van Amber says the individual scales rise and move around, which causes them to “get stuck to each other and interlock so you end up with a jumper that is three or five sizes too small”.
Once this has occurred, the change in the fibres cannot be reversed, the shrinkage is permanent, reducing your beautiful cashmere jumper to felt – which is great for craft or piano keys, but little else.
Fortunately, most wool items have been treated with something called shrink-proofing treatment which means they can safely be put in the washing machine. Still, Van Amber says that it is really important to follow the care labels.
Polyester should not shrink as much as natural fibres because polyester yarn tends to be manufactured as a very long single filament. Which means the yarn doesn’t need to be twisted as much as cotton, wool or linen, which have shorter fibres. Van Amber says this makes “synthetic fibres and fabrics more stable because the fibres are so long there’s not a lot of room for shrinkage”.
Steam is the only remedy
Generally speaking, it is very difficult to add the tension back into a garment that has shrunk. According to Steve Anderton, a laundry expert from the consultancy group LTC Worldwide, some professional dry cleaners can partially reverse relaxation shrinkage by using copious amounts of steam at very high temperatures. At home, he suggests turning the garment inside out and using an iron to press the fabric and seams under tension with a little steam, and maintaining this tension until the fabric is cool.
Van Amber also says you can try to unshrink things using a steamer or an ironing board but, unfortunately, it won’t be permanent. “The amount that you stretch it will remain until you wash it again, when it will probably shrink back.”
But she says you may have some luck with wool – as long as it hasn’t been felted. “The wonderful thing about wool is that you can iron and change the shape of it quite a lot through steam, I would iron it under steam and stretch it out quite gently.”