Growing up I was always told that cotton would shrink in the dryer but polyester wouldn't, and I should just check the tag on a shirt to find out if it would shrink (which usually would say something like 100% cotton, 100% polyester, 50% cotton/50% polyester, etc.). Seeing the title on this article made me think that it would be a refutation of that conventional wisdom, but it sounds like what I was taught growing up was basically correct.

I can't help but be curious now; is this something that other people my age (born in the early 90s) had heard when they were kids? Did people who grew up earlier than that hear it when they were kids, or did this idea maybe not reach mainstream status until a bit later (maybe my parents were relatively early in repeating this wisdom)? Or maybe it's something that used to be common knowledge that's been "lost" to newer generations for some reason? I'm genuinely a bit surprised to see that this article was published just last summer, since I assumed that the basic premise would be have something the average person would have learned before then from existing sources. Maybe I'm assuming too much about whether this article was intended to be about the "what" rather than the "why", but the language seems intended to be approachable to those from a non-scientific background (e.g. "on a chemical level, there are also links between the chains called hydrogen bonds"; I would expect someone talking to another scientist to be more direct and say something like "there are hydrogen bonds" with the expectation that they understood what they were already).

You need to be constantly updating your knowledge in this area. Laundry detergents and garment materials have evolved a lot in the last few decades. A lot of conventional wisdom is outdated.

You don't need to wash Hot. Detergents work in cold water now.

Cotton is often pre-shrunk but YMMV.

Personally I do not use any of these chemical additives for clothes. The best wash is unscented detergent with vinegar in the pre-wash (where liquid fabric softner goes). Vinegar does the job of deodorizing, getting rid of static, and fabric softening. You don't need a dryer sheet. I'll use spray and wash still for stains. Dish detergent for oil stains.

I stopped wearing plastic so I'm not sure what modern polyester shirts are like.

Washing cold and drying low means you'll rarely shrink something. My favorite shirts I'll hang dry.

Uniqlo and Patagonia specifically test their products through wear and tear and wash//dry cycles sources (others, too) - https://www.newyorker.com/magazine/2025/09/22/inside-uniqlos... and Let My People Surf. I think most other stuff we commonly see at retail has degraded to fast fashion and meant to only last a short time. The lifetime warranty and repairs offered by Patagonia speak for themselves I think.

Cotton shrinks, and that your dryer is too hot or running too long. Born in the late 80s, I think this was even a joke on sitcoms at one point (I have this vague memory of a husband pulling his favorite shirt out of the dryer and wearing it while it was still damp just so it wouldn't shrink), so it seems more like previously-common knowledge that was lost.