How many times do blue jeans shrink, if you continue to wash or dry in hot temperature?
This is a great question! Shrinkage not only varies from fabric to fabric, but also between similar fabrics (like blue jeans, for example) produced by different manufacturers. So how much a pair of blue jeans will shrink really depends on what steps the manufacturer took to control shrinkage during production. It may be helpful to understand why fabric shrinks in the first place.
During the process of spinning fibers into yarn and weaving or knitting yarn into fabric, the yarns and fabric are held under tension. When the tension is released, particularly when fabric gets wet during washing or tumble drying, the fibers, yarns, and fabric weave all “relax” and the dimensions of the fabric shrink, usually mostly in the length (warp direction). If the jeans fit tight in the waist when you put them on after washing, you are reintroducing tension and the jeans usually loosen up a bit after an hour or so. It’s harder to reintroduce tension to the length to get the legs to stretch out, although hanging wet blue jeans to dry from the hemline of the legs instead of the waist can help. That’s because the weight of the wet fabric stretches out the jeans a little.
If the fabric manufacturer includes any processes that reduce future shrinkage, or if the garment manufacturer prewashes the fabric so it relaxes, those items should be labeled “Preshrunk” on the hang tag. It is interesting to note that a garment that is preshrunk may still shrink a little with home laundering and drying, but not very much.
Consumers often have different desires for shrinkage: the tall person wants to avoid it and the petite person would love to not have to re-hem everything. If you have washed your blue jeans a few times hoping they would shrink and they haven’t then chances are the fabric was preshrunk during production. If they keep shrinking each time you wash them and you are wondering when is it ever going to stop, then they probably weren’t preshrunk. In general, you can expect up to 3-4% shrinkage, which on a pair of jeans with a 30” inseam would mean shrinking about 1” – 1 ¼” in the length. But this will vary from brand to brand and style to style. Shrinkage over 5% is generally considered unacceptable.
I hope this information is helpful. Please let me know if you have any other questions, and thanks for writing!