Does Polyester Shrink In The Washing Machine or Dryer?

Are you one of those people who throws items into the washing machine without checking the label? It’s all fine – until your favorite top shrinks!

And then we start to question what materials can or can’t go where…

One particular label that you might see often is for polyester blend. This is where things get a little bit confusing.

Does polyester shrink in the washing machine or dryer?

Polyester is unlikely to shrink in the washing machine or dryer. Fabric that is 100% polyester will only shrink if soaked in boiling water or left in a hot dryer for a long time. However, polyester blend fabrics, especially polycotton, shrink easily in hot water or a hot dryer.

If in doubt, checking the care label of your garment will tell you what fabric it is made of and how to launder it.

Let’s look at how polyester will react in a washer and dryer and what will cause it to shrink. 

Can Polyester Shrink?

Polyester does not shrink under normal circumstances – in fact, to shrink 100% polyester, you have to make a real effort and use dangerous levels of heat, which may melt rather than shrink it.

Polyester is a synthetic fabric that consists of plastic polymer fibers. It was created to be strong, durable, and resistant to shrinkage, stretching, or creasing. This fabric can be treated to be completely water-resistant as well.

These shrink and crease-resistant qualities make polyester an appealing, versatile, easy-care fabric, useful for endless applications: wash-and-wear clothes, uniforms, bedding, drapery, and soft furnishings.

So long as you wash and dry polyester at regular settings, it should be virtually indestructible.

However, when polyester is blended with other natural or synthetic fibers, these qualities change, and the fabric may tend to shrink.

Polyester blended with cotton, linen, spandex, and rayon are all shrinkable because the blended fibers shrink.

Does Polyester Shrink In The Washing Machine?

Pure polyester shouldn’t shrink in the washing machine if you use cool (60-80⁰F/30⁰C) or warm (90-110⁰F/40⁰C) settings.

For 100% polyester to shrink, the water temperature must reach 230⁰F (110⁰C).

If you always use the hottest setting, you may see slight shrinkage, but it will not be noticeable. We like to be environmentally friendly and stick to a cool or warm wash.

Do Polyester Blends Shrink In The Washing Machine?

Polyester blends respond to washing differently to 100% polyester and are liable to shrink.

Let’s look at how these blends react to being washed.

Does Polycotton Shrink In The Washing Machine?

A polyester and cotton blend, often called polycotton, makes a breathable, durable fabric – that will, unfortunately, shrink in a hot wash.

The higher the proportion of cotton in the blend, the more the fabric will shrink. Conversely, the more polyester in the mix, the less likely it is to shrink. Pure cotton shrinks readily, while a 50% cotton and 50% polyester will shrink less than a blend of 65% cotton and 35% polyester.

Fortunately, polycotton will shrink only the first time of washing, keeping its shape after that. 

To prevent your polycotton garments or bedding from shrinkage, always wash on a cold setting.

Does Polyester-Rayon Shrink In The Washing Machine?

Rayon is a semi-synthetic fiber made from chemically treated cellulose. It has a beautiful silky texture – unfortunately, it does shrink in warm water. Unlike cotton, this fabric will also shrink repeatedly every time you wash it.

However, rayon is a very delicate fabric. Even when combined with the sturdier polyester, it does not withstand the friction and agitation of a standard washing machine cycle, whatever the temperature.

Ideally, wash polyester-rayon blends by hand in cold water or on gentle, cold wash in the machine to protect your flimsy blouses, dresses, or lingerie.

Does Polyester-Spandex Shrink In The Washing Machine?

Like polyester, spandex is a synthetic fiber, so it does resist shrinkage more than natural fibers.

Polyester and spandex blend to create a highly elastic fabric, often used for sportswear and stretchy underwear. They also blend to make scuba fabric, one of the trendier dress fabrics at the moment.

Polyester-spandex items can comfortably be washed on a warm cycle with a cold rinse. The more spandex in the polyester blend, the more likely it is to shrink at hot temperatures.

Wash all items containing spandex on a cool washing cycle to be safe.

How To Prevent Polyester Shrinking In The Washing Machine

Whether you’re washing 100% polyester or a poly-blend, always check the fabric care label for the manufacturer’s recommendations.

• Wash all delicate items by hand.
• Use a cold washing cycle or a temperature under 100⁰F (40⁰C) when in doubt.
• Turn all articles inside out to prevent fading and snagging.
• Set the machine to permanent press, which means slower spin cycles and less friction, leaving your items with fewer creases.
• Use regular laundry detergent.

Does Polyester Shrink In The Dryer?

Polyester is unlikely to shrink on a regular cycle in the dryer. 

However, if you leave polyester in a hot dryer (over 100⁰F/40⁰C) for an extended period, you can shrink polyester. This shrinkage results from a combination of motion and dry heat, which makes even the polyfibers constrict.

Polyester dries quickly, so it’s easy to hang it out for a couple of hours if you want to avoid using the dryer.

Do Polyester Blends Shrink In The Dryer?       

Polyester blends can shrink and get damaged in the dryer:

• Polycotton will shrink if you dry it on a hot setting, so stick to the lowest possible.
• Never put polyester-rayon blends in the dryer as they are too delicate. Hang up small items to air dry or lay them flat on a towel, so they do not stretch.
• Spandex-polyester blends can go into the dryer, so long as you keep it on the coolest setting. This blend tends to develop static electricity, so use a dryer sheet.

How To Prevent Polyester Shrinking In The Dryer

Always check the fabric care label before putting any item in the tumble dryer. Follow these guidelines to avoid shrinkage and damage to your polyester and polyester blends:

• Never expose polyester to dryer temperatures over (over 100⁰F/40⁰C) as this heat can cause shrinkage.
• Use the dryer’s cool dry or tumble dry setting, as polyester and poly-blends dry very quickly without heat.
• Use dryer sheets or remove the items while slightly damp and hang up to air dry. This will avoid static build-up and creasing, especially in poly-blends.

How To Shrink Polyester

Shrinking an item by accident is annoying, but what if you want to deliberately shrink a polyester item, for instance, a shirt that’s slightly too big? 

There is only one way to shrink polyester – carefully controlled high temperatures.

However, pure polyester is unlikely to shrink a lot – you’ll have more success shrinking polyester blends.

Using Your Washing Machine To Shrink Polyester

You can use your washing machine on its hottest setting to help you shrink your polyester items:

• Turn items inside out before washing.
• If the article or garment is polycotton, a hot wash will shrink it.
• If you’ve got a spandex-polyester or pure polyester item, a hot wash is the first step in shrinking it.
• Never wash polyester-rayon blends in the washing machine or hot water, which will shrink but damage the garments.

Using Your Dryer To Shrink Polyester

You can also use your dryer on a hot setting to shrink polyester and polyester blends:

• Turn items inside out before drying.
• Polycotton items can shrink as much as 5% in the dryer on a hot setting.
• After the hot wash, put polyester and polyester-spandex items in the dryer. Leave them at the dryer’s hottest setting for as long as possible.
• Never put polyester-rayon items in the dryer.

Using Boiling Water To Shrink Polyester

The best way to shrink 100% polyester is to soak it in boiling water, which will constrict the fibers.

• Boil a pot of water.
• Remove the pot from the heat.
• Soak your item for five to ten minutes.
• Take care when removing the garment – the water will still be dangerously hot.
• Roll the polyester garment in a towel to remove excess water.
• Dry by laying the garment on a dry towel or hanging up to air dry.

Using An Iron To Shrink Polyester

You may come across suggestions to iron polyester items on hot, using a towel. Be careful of this approach as you will warp, scorch or melt the fabric rather than shrink it.

Never use a hot iron on polyester-rayon or polyester-spandex blends, as you will damage the fabric.

How To Unshrink Polyester

One advantage of 100% polyester is that you can unshrink it by stretching the fibers.

Unfortunately, this process doesn’t work for polyester blends.

• Fill a tub or your sink with lukewarm water. Add two teaspoons of hair conditioner.
• Soak your polyester items for 15 minutes.
• Lay out a towel to dry the item – or use a sweater-drying rack.
• Remove the garment and rinse under cool running water.
• Do not wring or squeeze the garment. Roll it in two towels and gently press out the excess water.
• Lay the item flat on the drying towel. 
• Spread the item out and use clothespins to pin the edges of the garment to the towel, stretching it slightly. You can also use small weights.
• Once the item is dry, it should have stretched back into shape.

The Bottom Line on Shrinking Polyester

Polyester was made shrink-resistant, so it is unlikely to shrink from a regular washing or drying cycle.

However, polyester blends will shrink in warm washing and drying cycles, so check your fabric care label before doing laundry.

To shrink polyester, you need to expose it to prolonged high temperatures by washing it in boiling water and drying it in a hot dryer.