# A Scientist’s Guide to Wrinkle-Free Clothes

## Метаданные

- **Канал:** SciShow
- **YouTube:** https://www.youtube.com/watch?v=_TF8AX-ktEk
- **Источник:** https://ekstraktznaniy.ru/video/25441

## Транскрипт

### Segment 1 (00:00 - 05:00) []

I hate ironing! There! I said it! The only reason I’m wearing this jacket today is because the part of it that’s wrinkled is out of frame. Sure, ironing gets the wrinkles out, and my clothes are nice and crisp afterwards. But it also takes forever, and I’d really rather just throw everything in the dryer and be done with it. It turns out, a bunch of scientists feel the same way. They’ve studied why your clothes end up wrinkled in the wash, and exactly how to get them to come out less rumpled. So here are some science-backed ways to help make looking sharp less of a pain. [♪ INTRO] On their long journey through the washer and dryer, there are a lot of factors that determine how wrinkled your clothes will be. And you might be tempted to start at the very beginning with detergent. But don’t be fooled. That’s not the solution. I mean, detergent is a liquid solution, but it won’t make your wrinkles go away. Some scientists decided to measure whether it has any impact on how wrinkled your clothes are when they come out of the washing machine. In a 2003 study, researchers threw a bunch of fabric into a washing machine, with and without detergent. Then, when the cycle was done, they gave each fabric a score based on how wrinkly it was. Technically, when they crunched the numbers, detergent made the fabric slightly more wrinkly. But it was pretty hard to actually see that difference in the clothes themselves. So if you were hoping that your detergent might help smooth things out, that study might throw a wrinkle in your plans. Speaking of liquids you might add to your washing machine, fabric softener doesn’t seem to make much of a difference either. Millennials everywhere, we can rest easy. It might make your clothes feel softer and smoother when you put them on. But its effect on wrinkles depends more on how the fabric dries. In a different 2003 study, scientists washed clothes with fabric softener and rated each item’s wrinkliness once it had finished drying. Clothes that were washed with fabric softener and then tumble dried came out slightly less rumpled than clothes washed and dried without fabric softener. So technically it might help, but it didn’t turn out to be a significant difference. Now, if the clothes were washed with fabric softener and then line dried, they could come out more wrinkly than clothes washed without fabric softener. Which is the opposite of what we’re going for! Scientists aren’t sure exactly why this happens. One possibility is that fabric softener might lock in wrinkles because it’s usually added at the end of the wash cycle. It comes in with the water that rinses out the detergent. At that point, the fibers in the fabric are swollen with water and bunched together. The fabric softener might coat the fabric in such a way that it locks all the bunched-up fibers in a rigid shape. That could set some of the wrinkles in the fabric. And tumble drying might be able to knock out those wrinkles, but line-dried items would be stuck with them. On the whole, though, fabric softener isn’t going to do much about wrinkles either way. The tumble-dried clothes were less wrinkly than line-dried clothes, regardless of whether the wash cycle included fabric softener. If you want neat clothes, you’re probably better off just chucking them in the dryer, assuming they can handle it, than worrying about exactly how much fabric softener to use. So detergent and fabric softener don’t really matter. And neither does the material thickness. Some types of fabrics wrinkle more or less than others, sure. We’ll get to that in a minute. But a 2017 publication demonstrated that when you’re considering two cotton fabrics, for example, the thickness of that fabric doesn’t seem to make a big difference in how wrinkly it gets. That’s true after both washing and drying. But different fabric types do make a difference. In a 2020 study, researchers found that knitted fabrics almost always wrinkle less than woven fabrics after washing and drying. This has to do with how much space the threads have in each material. The yarn in knitted fabrics has more space to wiggle and shift around than the threads in a more tightly woven fabric. When fabric bumps around in the dryer, the yarn can settle back into its regular layout and shake out some of the wrinkles that form in the washing machine. It’s easier to knock those wrinkles out when the fibers have more freedom to move and adjust. And that’s also going to depend on the chemical makeup of the fibers in a fabric. As I mentioned earlier, being soaked with water makes a difference in how wrinkly your clothes come out. So cloth will wrinkle differently depending on whether its fibers attract or repel water. Cotton fibers have an affinity for water. They’re hydrophilic. At the atomic scale, a cotton fiber has lots of hydroxyl groups that each have an oxygen and a hydrogen atom. This is similar enough to water, with its two hydrogens and an oxygen, so that the two can comfortably mix and mingle with each other. So, in the washing machine, when cotton fibers absorb water and swell up, their hydrogen atoms can form hydrogen bonds with oxygen atoms in water or another fiber. And vice versa. Once the fabric starts drying and all the water gets pulled out, the fibers can only hydrogen bond with each other. If the fabric is all bunched up, those new bonds can lock in wrinkles. So generally, hydrophilic fabrics like cotton tend to come out wrinklier after several washes than they did after the very first wash.

### Segment 2 (05:00 - 10:00) [5:00]

But those hydrogen bonds aren’t permanent. Heat and the mechanical action of flopping around in the tumble dryer can knock some of those wrinkles back into that original smooth surface where they belong. And some synthetic fibers, like polyester, don’t grab onto water the same way because they’re hydrophobic. That means they tend to wrinkle less when you wash them. But that doesn’t mean they don’t wrinkle at all. Once you heat up polyester fibers enough, the individual chemical chains that make up that polyester get a little loose and bendy. They’re too tangled up with each other to fully melt, luckily for your shirt. But they can bend and shift and rearrange, much like the hydrogen bonds in your cotton clothes. For polyester, this will happen between 67 and 81 degrees Celsius. So if your dryer gets hotter than that, the molecules in your shirt get a little wiggly. And once your clothes cool down, that rearrangement might leave some wrinkles behind. But, regardless of the fabric, there are ways to prevent wrinkles before they even form. And before I get into those ways, it’s time for an ad break. All research needs funding, including ours. Thanks for watching SciShow for the last 14 years! If you want to see us make it to 15, pause this video and go to complexly. org/supportscishow. I’m serious. Pause the video and go there. This year, our postcard campaign is a little different. We’re celebrating the scientific process by looking at X-Ray Crystallography. By shooting an x-ray through a crystal and creating patterns like this, scientists were able to prove things that had only been theorized. To us, these cool little dots symbolize something we care about a lot at SciShow: Science is a process! It’s a collaboration. And we’re still in the middle of it! For $60, you get a postcard with cool removable stickers. For $500, you’ll get a steel spinner with the scishow logo. It’s all at complexly. org/supportscishow Thank you for doing what you can to keep SciShow around for another year. And... donate responsibly! Some clothes come with a wrinkle-free treatment already applied. That way, you don’t have to think too hard about how you’re washing and drying them. Wrinkle-free treatments have been around since the 1950s. Typically, a resin and a softener are applied to your garment before it hits the shelves. That prevents the fabric from shrinking and keeps the fibers from squishing together. As with knitted fabric, when the fibers have room to move around and return to their original shape in the dryer, they’re less likely to wrinkle. The wrinkle-free treatments work … at least for a while. But they don’t last forever. The more clothes are washed, the more they lose those softeners. You can start to see these effects in just 4 washes. One study from 2002 found that fabrics got stiffer and less stretchy as the treatment wore off. Pretty much exactly what you’d expect now that you know the chemistry. Since wrinkle-free treatments aren’t a forever solution, here’s some other things to try. One study published in 2017 suggests that doing a bigger load of laundry can lead to more wrinkles. Which…look, I get it. I don’t want to spend my whole day doing laundry either. It’s super tempting to try to cram everything into one load and then go do something else. But your clothes might come out more rumpled for it. As clothes bump around against the washing machine and each other, they get more and more wrinkled. So the more stuff there is to bump into, the more likely you’re going to end up with wrinkles. Those researchers found that filling your washing machine even halfway spit out some fairly wrinkled cotton. That said, tumble drying can knock out some of those wrinkles. So maybe you’ll be okay with sticking a few extra shirts in there if you’re not line drying your clothes. And there are still a few other things you can do to minimize how much your clothes are bumping around in the wash. Like, a slower or gentler washing cycle could help smooth things out. Research has shown that as a washing machine drum rotates faster, it applies more force to the fabrics inside, which bends them out of shape and makes them more wrinkly. But spinning too slowly can make it hard to get all the detergent out of your clothes. So you might want to weigh your options with this one. Even the amount of water in your washing machine can make a difference. The same study found that more water in the machine made clothes less wrinkly after a wash. That extra water made the fabric less likely to bend and crinkle under stress. Everyone’s washing machine is different. But a 2013 study found that using 16 liters of water, which was on the upper end for that machine, spit out less wrinkled linens than a load with just 12 liters of water. But there are two parts to every laundry cycle. The way you dry your clothes might be more influential in the end, as far as wrinkles are concerned. The reason tumble drying your clothes generally leaves them smoother than line drying has to do with the combination of heat, steam, and mechanical action. Together, they help relax the fibers and reset those hydrogen bonds we talked about earlier. Based on limited data, it seems that the longer you dry them for, the better, at least in terms of looking crisp. The same 2003 study that looked at the effects of fabric softener found that tumble drying clothes for 45 minutes left them smoother than after just 30 minutes. Of course, even if you pay careful attention to your washing settings, your fabrics, the care instructions, everything, you might still end up with a few wrinkles. And let’s be real, those clothes are still wearable. But your final hail mary if you really need to look crisp after forgetting a load of laundry

### Segment 3 (10:00 - 10:00) [10:00]

in the dryer are tried and true methods that you’ve probably tested in the laboratory of life. Like throwing the clothes back in the dryer for a few minutes with a damp towel, steaming them, or hanging them up in the bathroom while you take a nice, hot shower. And if all else fails, you can always break out the old iron. As much as I hate them, irons work. [♪ OUTRO]