Does Polyester Shrink?

We spoke to a couple of experts to learn more about this fascinating synthetic material. Then, we tested a few methods for shrinking polyester ourselves to learn the effect on different clothing items, including knits, workout wear, and poly blends.

"Polyester is a synthetic, man-made fiber made of petroleum," Melanie DiSalvo, a textile science graduate at the Fashion Institute of Technology and founder of Virtue + Vice (a consulting company specializing in helping companies launch and scale sustainable fashion businesses), tells Hunker. It is made into yarn by extruding liquid plastic through a spinneret, which she says "looks like a teeny-tiny spaghetti strainer."

While polyester was invented in the late 1930s, it was largely ignored at first in favor of another synthetic fabric discovered around the same time: nylon. When the war broke out, polyester continued to be overlooked, as nylon became a critical war resource since it could be used to create military gear, such as parachutes. It wasn't until the 1950s that polyester was produced commercially, when it was sold under different manufacturer names, including Terylene, Dacron, Kodel, Fortrel, and Vycron.

The fabric continued to soar in popularity through the 1960s but fell out of favor by the late 1970s, when youths started associating it with their parents' out-of-style leisure suits. In the 1980s, though, big-name designers started incorporating polyester and poly blends into their fashion lines, leading to a resurgence. Frequently used by fast-fashion companies, polyester is now one of the most commonly used fabrics in the world.

While polyester once had a bad reputation for being cheap-looking, uncomfortable, hot, and scratchy, modern polyester and poly-blend fabrics look and feel luxurious and comfortable. Polyester clothes are easy to care for as well as wrinkle-resistant and fast-drying. Some can even wick away moisture. The material is often added to other textiles, such as wool and cotton, to make them stronger and more resistant to rips, shrinkage, and wrinkles.

That's not to say that polyester is without its downsides. It tends to absorb body odors, which can be challenging to remove from the fabric. Even worse, the material is basically plastic, so you're likely releasing microplastics down the drain every time you wash it. And that's not the only way that polyester is bad for the planet. With 85% of all textiles ending up in landfills every year, it's a real problem when the material is nonbiodegradable, like polyester, which can take hundreds of years to decompose, according to Frej Lewenhaupt, a textile expert who is the co-founder and CEO of Scandinavian textile-care company Steamery.

Polyester fibers themselves do not shrink, according to DiSalvo. Part of the material's easy-to-care-for reputation comes from the fact that it can be washed on high heat and tossed in the dryer without worrying about shrinkage. However, many fabrics made with polyester can shrink either because they are made from a poly blend or because the material is knitted. Clothes can absolutely shrink if they are made from a combination of polyester and another material that does shrink, like wool or cotton.

Even 100 percent polyester clothing can shrink if it is knitted rather than woven. Items like jeans are woven, while T-shirts and sweaters are knitted. "Wovens tend to be more stable and [do] not shrink," says DiSalvo. However, the construction of knitted fabrics allows them to stretch a lot, and these fabrics can also shrink. "What is happening is not the fiber itself shrinking but the construction of the fabric in the garment," she says.

Polyester fibers may not shrink when exposed to excess heat, but they can melt, which is similar to shrinking. Melting does weaken the integrity of the fabric. DiSalvo says polyester becomes weakened and brittle when placed under high temperatures in the manufacturing process, so very high temperatures in your washer or dryer can do the same, which does cause the material to wear out faster.

Even so, 100 percent polyester can hold up well to temperatures up to 139 degrees. Because the fabric is designed to be easy to care for, you can typically wash and dry polyester without any issues. In fact, it's a good idea to wash sweaty polyester workout wear on the highest possible temperature setting to help kill odor-causing bacteria that may get trapped in the fabric (especially those stubborn armpit odors in shirts).

When it comes to shrinking polyester clothes, whether you are trying to shrink a shirt, blouse, T-shirt, hoodie, or skirt, the process all comes down to heat — meaning a high heat of at least 140 degrees Fahrenheit and preferably between 155 and 178 degrees. That being said, your success rate will vary based on whether the item is 100 percent polyester or a blend and whether the fabric is woven or knitted.

Poly blends usually shrink more quickly and effectively than polyester, especially if the material is less than 50 percent polyester. The methods below are designed for knitted 100 percent polyester clothes (so if you need to know how to shrink poly-blend fabrics, you should reduce the temperature slightly based on the material's blend).

Similarly, while pure woven polyester is practically impossible to shrink, knits may shrink slightly when exposed to heat. Even so, the process is still difficult, and the results will usually be uneven, meaning the clothing will be unlikely to have the same proportions as it did before you exposed it to high temperatures. "This is not something that I recommend since this requires a lot of energy and will likely create unnecessary tearing on your clothes, causing them to lose their shape, color, and luster," warns Lewenhaupt.

While you can check the tag to see the fabric composition, the best way to check if the material is knitted or woven is to give your clothes a gentle tug. If the material is stretchy, it's probably knitted; if not, it's most likely woven.

Here are a few methods for shrinking polyester:

1. Flip the clean garment inside out to help protect its detailing and colors. (High heat can sometimes fade colors).
2. Then, wash it on the longest cycle using the hottest heat setting with no detergent.
3. If it has shrunk enough, air dry it or tumble dry on low, but if you need to shrink it more, try one of the other recommended methods below.

If washing on a high temperature didn't shrink your clothing enough, you can try boiling it.

1. Fill a large pot of water deep enough that the garment can move around while staying fully submerged and place it on the stove to boil.
2. If your clothing is dry, wet it and flip it inside out before adding it to the pot. Otherwise, take it right out of the washer and place it in the boiling water while it is still wet and inside out.
3. Boil the clothing for up to an hour, periodically stirring and checking how much it has shrunk.
4. Let the water cool until you can safely remove the clothing and then air dry or tumble dry on low heat if it is already small enough or use the dryer or ironing methods below to continue the shrinking process.

Ordinarily, polyester does not shrink in the dryer, but if you place wet polyester clothing in the dryer on the highest possible heat setting for the maximum cycle length, it may. For best results, try to shrink the garment using one or both of the methods above and then immediately put it in the dryer.

When working with poly blends, start with a lower temperature and a shorter dryer cycle and work your way up until you get satisfactory results.

Polyester typically doesn't need to be ironed because it is very wrinkle-resistant. But the high heat from an iron can be enough to shrink the fabric, even if hot water doesn't do the trick.

1. Take a garment you boiled or washed on high heat and place it on an ironing board while still wet.
2. Then, cover it with a pressing cloth or towel.
3. Set your iron to low or medium heat with no steam.
4. Then, gently run the iron over the cloth or towel, moving it in a circular motion until your clothing is entirely dry.

• In this section, we will test shrinking polyester using test T-shirts, hoodies, and workout clothing and by using multiple washing and drying sessions.

If you looked up "does polyester shrink" on Google because you like your clothes the way they are, here's some good news: As hard as it is to shrink polyester on purpose, it's nearly impossible to do it by accident. Even so, if you're worried about damaging your favorite polyester or poly-blend clothing, the main thing you need to worry about is heat, so simply avoid using excess heat while washing or drying your clothes. Always follow the care label on your garments to avoid subjecting them to damaging products or washing methods.

Because workout wear should typically be washed with high temperatures to kill odor-causing bacteria, consider turning your water heater's temperature down to 120 degrees, which is eco-friendly and too cool to shrink polyester. Alternatively, you can "steam polyester clothing between washes since the hot steam from the steamer not only removes wrinkles but also kills bacteria and removes unwanted odors," says Lewenhaupt. As a bonus, "washing less will decrease the likelihood of shrinking."