How a fabric is pre shrunk
Short answer: Pre-shrinking means the fabric gets steam and heat under low tension, so the loops draw together before the pieces are cut. The shrinking then happens at the factory instead of at your home, and the measurements stay more stable from the very first wash.
The tension has to leave the fabric
After knitting and dyeing the fabric is stretched, because it is pulled through machines that hold it out in width. That tension stays in the yarn and the loops. Pre-shrinking lets the fabric relax and find its natural shape before anyone starts to cut the pieces for the garments.
What the word pre-shrinking means
The word covers a treatment that makes the fabric shrink in advance. The idea is simple: what would otherwise happen in your washing machine happens under controlled conditions at the producer instead. The size of the finished garment then sits closer to the size guide, even after a few washes.
Steam and heat do the work
Moist heat makes the fibres swell a little and the loops find their resting shape. The fabric is then dried without pull, so it is not stretched again. It is a calm process that takes time and energy, but it makes the fabric easier to work with. See bamboo shirts for women.
Resting before cutting
The fabric should lie until it has let go of the last pull. If it is cut too early, the pieces can draw together afterwards and end up smaller than planned. The resting time is therefore a small but important link between pre-shrinking and cutting, even if none of us can see it on the finished garment.
Why the measurements become stable
Once the fabric has already drawn together, less is left to happen in your wash. That makes it easier for the producer to keep the measurements in the size guide. For you it means a size M stays roughly a size M, and sleeves and lengths do not change much after the first time in the machine.
The result is fewer surprises
A pre-shrunk fabric typically shrinks under two percent in the first wash. Without the treatment the figure can be double or more. The difference shows in sleeve length and body length, especially if you tend to choose a close fit. See also offers for women and Urban Quest for garments to compare.
It still shrinks a little
Pre-shrinking removes most of the shrinkage, but not all. The fibres still react to heat and moisture, and a very hot wash or a tumble dryer can draw the fabric together again. So do not count on total freedom, count on a more predictable starting point for the fit in everyday life.
How to wash it the first time
Follow the care label in the garment and choose a low temperature. Skip the tumble dryer if the label advises against it, and hang the garment up without pulling at it. That keeps the measurements the pre-shrinking made stable, and the garment holds its shape longer in ordinary use.
How to choose your size
Pick the size you normally wear and check the measurements in the size guide if you are unsure. A pre-shrunk fabric makes it easier to get it right the first time, but it does not change that the fit depends on the cut and the body. Try the garment and wash it once before you decide on an exchange.
Frequently asked questions
Does pre-shrunk fabric not shrink at all?
Yes, a little. The treatment removes most of it but not all, so expect a small change in the first wash, especially at high temperature or in a dryer.
Can you pre-shrink a fabric yourself?
Yes, by washing and drying it the way the garment will later be treated, before you sew or use it, so the shrinking comes first.
Why do not all factories do it?
Because it is an extra step that costs time and energy, and not every producer chooses to use it on every fabric they work with.
You can find the full range at Bamboo-Clothing.com.
