All underwear made of cotton knits is subject to shrinking – the finer the fabric, the more so. As long as laundry was traditionally air-dried, this was no real problem; it only became critical with "over-drying" in tumble dryers.
The industries involved in producing knitted cotton underwear, together with the Institute for Textile and Process Engineering (ITV) in Denkendorf, have drawn up a guideline: according to the ITV test procedure, only knitted underwear that shrinks by less than 11% qualifies as tumble-dryer-safe. With the right starting size, this shrinkage value does not affect the fit – all manufacturers who care about product quality adhere to it. With inferior products, however, tumble-drying can cause shrinkage of more than two garment sizes.
Using Relax and Santex dryers as well as the stenter frame, the fabric is given the desired shrinking properties plus a soft, pleasant handle. Single jersey, interlock and other qualities additionally receive the Toptex finish (comparable to sanforising) for extra low shrinkage – along with a fine sheen and an even softer feel.
Learn more about the refining of underwear fabrics in our Underwear Glossary.
