The seam that turns around the body
Short answer: A side seam that no longer runs straight down is not sewn crooked. It follows a fabric that has turned, because the twist in the yarn pulled it sideways in the wash. It does not look neat, but it does not affect strength, and it can often be prevented at the factory.
The seam does not move by itself
The seam sits where it was sewn and cannot wander on its own. It is the fabric around it that has changed shape, and the seam simply follows it around the body. A crooked seam therefore shows that the fabric has turned, not that anyone sewed it wrongly.
How the twist arises
Yarn is twisted, much like a rope, and the twist stays in the yarn even after it is knitted into fabric. If all the yarns twist in the same direction, the fabric wants to turn a little as soon as it gets the chance. This is most visible in tube knit, where the fabric forms a cylinder.
Why it happens in the wash
In water the fabric relaxes, and the tension built in during knitting and pressing is free to act. When the yarn is twisted one way, the whole tube turns. It rarely shows after the first wash but can become clear afterwards. To compare models, see bamboo sweatpants for women.
What you can do at home
The twist cannot be fixed at home, and pulling hard on the fabric rarely helps. You can follow the care label, avoid the highest temperature and lay the garment flat to dry so it does not hang crooked. That does not stop the twist entirely, but it helps the fabric settle after washing.
What the factory can do
The factory can prevent twist by fixing the fabric so the tension is taken out before cutting. It can also blend yarns with opposite twist so the forces cancel out. Both cost time and money, so you do not always see them. See also bamboo bodystocking and bamboo underwear for women.
How much twist is normal
A little twist counts as normal, and up to a few percent of the circumference is generally accepted in the industry. If the seam sits clearly at the front of the stomach or on the back, that is more than normal. Watch whether the garment still fits properly and the edges lie neatly.
Is it a fault
The twist is cosmetic and does not change the fact that the garment is wearable. The fabric is still whole and the seams hold as before. If you are unsure, or the seam sits far from where it should, contact customer service and send a photo. Then we can look at the individual item.
Does it get worse with every wash
No, most of it happens in the first few washes, and after that the fabric settles. Once the tension has been released, there is little left for it to turn against. If the garment has held its shape for a few washes without changing further, you can expect it to stay as it is now.
How to check your clothes
Lay the garment flat on a table and see whether the side seams lie on top of each other and point straight down. Then hang it on a hanger and see whether the seam falls straight. If you see a clear difference, the fabric has turned. Check after the first wash.
Frequently asked questions
How much twist is normal
Up to a few percent of the circumference is generally seen as acceptable in the industry. If the seam sits clearly at the front or back, that is more than normal, and you can contact customer service.
Can I still wear the garment
Yes. The twist is cosmetic and does not affect strength. The garment can be worn as normal, even if the seam no longer runs quite straight down beside your body.
Does it get worse with every wash
No. Most of it happens in the first few washes and then settles. Once the tension in the fabric has been released, little changes in the washes that follow.
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