Does Polyester Shrink? Yes! Here’s How To Either Avoid It Or Shrink It On Purpose
So, does polyester shrink?
Yes, polyester can shrink! Scientists have proven it! But what about when you’re washing polyester at home?
It’s pretty resistant but it can shrink if you don’t wash and/or dry it properly.
I’ve accidentally shrunk polyester fabric by forgetting to pre-wash it before sewing (oops)! This is why I’ve made it my mission that this won’t happen to me or others again, and I’m sharing my research and tried-and-true polyester care tips in this guide!
As well as how to avoid shrinking your polyester fabric and garments, you might actually want to shrink them and are wondering, “How do I shrink polyester?”. I’ll talk about that and also include a step-by-step guide on how to unshrink polyester.
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Table Of Contents
Does Polyester Fabric Shrink?
As sewists, the golden rule everyone knows (or should know) is that you MUST pre-wash your fabric before you start working with it. Why? So you shrink it before you sew it, not once you’ve sewn it – ouch.
I got curious though, as often when I get a new fabric, I want to start my project straight away, and wonder, do I REALLY NEED to wash this (or can I stick it in the dryer) so I can start sewing sooner?
So I decided to start looking into which fabrics I can do this with, starting with polyester.
I decided to start with the science and looked at several scientific journal articles that confirmed that, yes, polyester does shrink. The amount of heat you use seems to be the key.
This comparative study on polyester yarn and the fabric made with it (knitted fabric) found that yes, both the yarn and the fabric shrink, and that you start to see the changes when you use extreme heat:
“Noticeable changes in polyester thermal behavior occur at 160°C”
Their recommendation is that:
“it is safe and advisable to use low … heat setting temperatures where possible.”
Does 100% Polyester Shrink?
Yes, 100% polyester can shrink if you’re washing it in extremely hot water. It can also shrink in the dryer if the temperature is too hot.
If you wash and dry it in cold, cool (or maybe lukewarm) water it should be resistant to shrinking. Always check the care label before washing!!
Do Polyester Blends Shrink?
Yes, polyester blends can shrink. But it depends on what the polyester’s blended with. Read on for which blends shrink and which ones don’t – backed up with science.
Does Cotton Polyester Shrink?
Yes, cotton polyester can shrink.
A study by Dr Cevza Candan and Professor Levent Onal published in the Textile Research Journal states that “Cotton and cotton/polyester blended weft knitted fabrics are prone to shrinkage during … customer usage”. They saw shrinkage when they washed the fabric AND tumble-dried it.
They found that pique knit fabric shrank less widthwise but more lengthwise than the other cotton-poly knit fabrics they tested.
I know this is true as when pique knit polo shirts were all the rage, mine would shrink length-wise!! As in after I washed them (and especially dried them) my belly button would all of a sudden be on show lol.
Cotton polyester fabric DO shrink less than 100% cotton but they still shrink. In some instances up to 4% less, according to a study by Professor Chowdhary and Marsha (see table 9), published in the International Journal of Polymer and Textile Engineering.
Pique Knit Fabric T-shirt care label (65% poly / 35% cotton). Advises to allow for 10% shrinkage!
Does Polyester Spandex Shrink?
Yes, polyester spandex can shrink when exposed to high temperatures.
In fact, according to a literature review done in a study by Dr. Haitham, spandex is used with polyester and other fabrics ON PURPOSE because it does this! The more spandex there is the less the fabric will stretch.
Does Rayon Polyester Shrink?
Yes, rayon polyester can shrink. While I couldn’t find a scientific study on whether polyester rayon blends shrink, I was able to find some information about rayon in the Encyclopedia of Applied Plant Sciences and also use my own personal experience sewing with it.
In the above-mentioned book it states that “rayon shrinks… so that rayon textiles must normally be dry-cleaned.”
I wish I’d known that before washing my favorite rayon jump-suit which shrunk a lot (sad face)- mostly length ways, which was lucky, as I could still wear it and pretend the legs were meant to be that shorter length ;).
Based on this information, I would assume that poly rayon blends do shrink due to the rayon content but maybe not as much as pure rayon, thanks to the polyester.
I’m going to see if I can find a rayon-poly blend to experiment with, and I’ll report back here when I have the results.
Does 95% Polyester Shrink?
Yes, but just like 100% polyester, 95% polyester it’s pretty resistant to shrinking. As long as you don’t use too much heat when washing, drying or ironing it.
How much it shrinks also depends on what it’s blended with, for example, if it’s blended with spandex or cotton that’s not preshrunk, it may shrink more but if it’s blended with another synthetic fabric like nylon then it may shrink less.
Does Polyester Shrink When Washed?
Polyester shouldn’t shrink when you wash it with cold, cool or lukewarm water. Polyester can shrink if the water temperature is 230°F (110°C) or above.
Does Polyester Shrink In Hot Water?
Yes, polyester shrinks in hot water if the temperature is 230°F (110°C) or more.
Does Polyester Shrink In Cold Water?
No, polyester doesn’t usually shrink in cold water. It only shrinks if you use high heat, as the high heat makes the fibers and the “loops” shrink.
Cold water shouldn’t have this effect on the fibres and loops and is generally safe for 100% polyester and most blends (except poly/rayon).
Does Polyester Shrink In The Dryer?
No, polyester won’t shrink in the dryer, AS LONG AS YOU FOLLOW THE CARE LABEL and use a low heat setting. Polyester WILL shrink if the dryer is set on high, with a temperature of 135°F (57°C) or more.
Does polyester shrink in the dryer if it’s blended with cotton, rayon, or linen? Yes, it can, as these fibers are sensitive to heat too. For these blends, it’s best to avoid the dryer (or use the lowest setting, if you have no other option – but I wouldn’t do this myself).
Does Polyester Shrink When Airdrying?
No, polyester doesn’t shrink when you air dry it. This is my favorite way to dry polyester (and 99% of my clothes when I have the choice).
Does Polyester Shrink When Dry-Cleaned?
No, polyester doesn’t typically shrink when dry-cleaned.
Heat (and moisture) cause polyester to shrink, and the dry-cleaning process uses special machines called “chillers” and “water separators” that keep the solvents from getting too hot and your clothes from getting too wet.
IF one of those machines isn’t working properly, or if you are dry cleaning a “defective” piece of clothing, then your clothes could shrink when you dry clean them but this is the exception to the rule.
How Much Does Polyester Shrink?
Polyester can shrink between 3% to 5% in width and length if washed and dried at a high temperature.
Iron Settings For Polyester (To Not Shrink Or Melt It)
We’ve seen how polyester can shrink when handled on high heat, so will polyester shrink when you iron it? Yes, if you use too much heat. No, if you use low to medium heat.
Learn from my mistakes and AVOID high heat settings when ironing polyester!
I bought an ironing board with a 100% polyester cover (I didn’t realize) and although it didn’t shrink, I immediately ruined both the ironing board cover AND my iron by melting the polyester fabric onto the iron – gah!
I had to make a new ironing board cover using cotton canvas, so luckily I can still use it. I did however have to buy a new iron.
If your iron doesn’t come with a ‘polyester’ or ‘synthetic’ setting, then start with the lowest heat setting you can and slowly increase the heat (to medium) only if you need to.
You can also use a press cloth between your polyester fabric and iron (like a towel or a piece of cotton fabric to protect the polyester).
One great thing about polyester is that it’s naturally resistant to wrinkles, so if you’re working with 100% polyester there’s a high chance you won’t need to iron it. But of course, if you’re using a poly blend with a natural fabric like cotton or linen then you probably will need to.
How To Shrink Polyester
Can you shrink polyester on purpose? Yes, you absolutely can!
This method won’t work if you’re looking to shrink your clothes by a few sizes! If that’s what you need to do, exchange the item or buy a smaller size.
Step 1: Wash On High Heat
Heat is going to be your best friend here, so go ahead and wash your fabric on high heat. Go as hot as your washing machine will let you.
Step 2: Dry On High Heat
The same goes for drying the fabric – use high heat. Stick to the tumble dry option and use a setting that’s around 135°F (57°C), if available (which it should be as most tumble dryers go up to 150°F or 66°C).
Step 3: Repeat As Needed
Check your fabric to see if it’s shrunk to the size you want it to be. If not, you can repeat the wash and dry cycle until you get what you’re looking for.
How Do You Unshrink Polyester?
Now, let’s say you’ve accidentally shrunk your polyester clothes. You can try to stretch it back into shape with some conditioner (baby shampoo works too)! Here’s how:
Step 1: Prepare Soaking Solution
In a soaking tub, add 1 to 2 tablespoons of hair conditioner or baby shampoo to lukewarm water. Mix well.
Step 2: Soak Fabric For 20 – 30 Minutes
Add the fabric, and let it soak for 20 to 30 minutes. The shampoo or conditioner helps to relax the fibers, allowing you to slowly stretch them back.
Step 3: Dry & Stretch Fabric
Remove the fabric from the tub. Don’t rinse. Roll it up into an absorbent towel (a microfiber towel works great!) and squeeze as much of the water out as you can.
Lay the fabric flat on a dry towel. Carefully stretch all the sides out to set it back into the original size.
Step 4: Let It Dry
Keep the fabric flat on the towel and let it dry. You can add weights (or safety pins) to the sides of the fabric to keep them stretched out to where you want them to be.
And that’s all there is to it! Pretty easy, right?
Does Polyester Shrink FAQs
Does Polyester Shrink More Than Cotton?
No, polyester shrinks less than cotton! A study from Central Michigan University found that cotton shrinks up to around 3.5% more than poly-cotton blend t-shirts (depending on the area of the t-shirt measured).
Does 60 Cotton 40 Polyester Shrink?
Yes, 60% cotton 40% polyester shrinks if washed or dried using high heat. According to a study in the Textile Research Journal, poly-cotton blend t-shirts can shrink anywhere from 2.55% (chest) to 10.25% (neck opening).
How Do You Wash 50% Cotton 50% Polyester Without Shrinking It?
To wash 50% cotton 50% polyester without shrinking it, use cool water. You can hand-wash or choose a gentle cycle.
Air drying is the safest option to reduce shrinking. If you need to use a dryer, choose the lowest heat possible.
Why Does Polyester Shrink?
Polyester shrinks when it’s washed or dried using high heat, (according to Perera’s study at: 160°C) because the heat (and moisture) “changes the shape of the loop and/or thermal shrinkage of the stitch length”.
What Is Polyester?
Polyester’s a synthetic fabric. It’s also known as polyethylene terephthalate (PET). Fibers come from petroleum which are mixed with an acid to make it.
Fabrics can be 100% polyester or blended with other fibers to get the best of both worlds. For example, polyester helps cotton wrinkle less and it lowers the cost of linen.
Does Polyester Shrink: Summary
Yes, polyester can shrink if it’s not washed and dried properly – for example, if the water or tumble dryer is too hot.
But if you use the correct water/dryer temperature, your polyester fabric and clothes shouldn’t shrink (unless they’re defective).
One blend that you should be very careful with is polyester rayon. Rayon is very likely to shrink, so in this case you should only dry-clean.
If you want to avoid shrinking polyester, remember:
- Wash polyester with cool or lukewarm water. Avoid washing any hotter than 230°F (110°C).
- Air dry polyester fabric after washing, or use the low-heat setting on your dryer (only if you have to).
- Polyester doesn’t wrinkle much but if you need to iron it, choose a low-heat setting (and/or use a press cloth between the polyester and iron.
If you have any questions or other tips on caring for polyester, please let me know in the comments below!