Chances are that you often buy clothing without thinking about how flame-resistant it is unless you work in a high-risk environment as a welder or firefighter. You probably own a closet full of clothes made out of polyester, but you might not know a lot about this versatile fabric. For instance, is polyester flammable?
Like most synthetic fabrics, Polyester is not highly flammable. Polyester is naturally flame-retardant, but it does melt when it reaches a high temperature. Poly blends like polycotton can both burn and melt, depending on the nature of the fibers and the weave of the fabric.
In this article, we’ll look at polyester’s flame-retardant abilities. We’ll also compare polyester’s flammability to other fabrics, and discuss safety tips for handling polyester.
What is Flame Retardant Fabric
All textiles will burn in certain situations, but some fabrics burn slowly and ignite only at very high temperatures. Most synthetic fabrics are naturally flame-resistant. They burn at a much higher temperature than natural fabrics such as silk and cotton.
Natural fabrics burn easily, so they are sometimes treated with chemicals to make them flame retardant. Halogenated hydrocarbons, antimony oxides, and phosphate-based compounds are sometimes used to coat fabrics to prevent the fibers from torching if they contact a flame.
The thickness and weave of a fabric also impact its flammability. Anything that allows more space between fibers for oxygen is likely to be highly flammable. The loose weave of some cotton fabrics is a great example – air exists in all the tiny spaces between the cotton threads, making this fabric highly flammable.
Technically there is a difference between the terms flame retardant, flame resistant, and flame-proof when you’re talking about fabrics.
Flame-resistant fabrics are made from fibers that have a chemical structure that actually resists burning. These fabrics do catch fire at a very high temperature, but when you remove the heat source, the fire usually self-extinguishes (imagine if your sleeve brushed the open flame of a gas burner, but you yanked your hand away, removing your sleeve from the heat source).
Flame-retardant fabrics have been treated with chemicals to give them slow-to-burn, self-extinguishing properties. Again, these fabrics will burn in certain conditions, but the special chemical treatment lessens their flammability and slows the spread of a fire once it starts.
Flame-proof fabrics do not truly exist outside of science labs. There are some specialty “fabrics” made out of things like glass or asbestos that do not burn, but they aren’t practical or safe for production. Even the personal protective equipment or fire kit, worn by firefighters is made from Nomex, which is technically only extremely flame-resistant.
Is Polyester Flammable
Polyester fibers in synthetic fabric are not flammable. Polyester fabric, though, is only flame-resistant. This fabric will melt at a high temperature, but it resists burning. If you remove the burning fabric from its heat source, the fire self-extinguishes.
Before you go out and buy polyester socks to wear as you walk across hot coals, please remember that one of the dangers of polyester is that it will melt when it gets very hot. Melting may sound less scary than burning, but if you are wearing something that is essentially made of plastic, and it melts onto you, the results will not be pleasant.
Polyester is made out of chemicals derived from petroleum. Its chemical composition includes something called flame retardant comonomers. This means that even at a chemical level polyester does not burn easily. Keep in mind, though, that polyester is often blended with another kind of fabric (such as cotton, wool, or spandex). These poly blends can be much more flammable than 100% polyester.
In a poly blend, polyester fibers are twisted with the fibers of another fabric to create threads that are used to weave the fabric. Because of this, the flame-resistant polyester fibers are mixed with naturally flammable fibers. These blends can also be loosely woven, which also increases the fabric’s potential flammability.
Does Polyester Melt?
We now know that polyester is inherently flame-resistant and does not burn easily, so what causes polyester to melt? The melting point of 100% polyester is 260℃/482℉. If you just read that and sat back with a sigh of relief, thinking “I’ll never be around anything that hot,” think again! Polyester is prone to melting under the wrong iron settings, and sometimes even in a dryer set to high heat.
It goes without saying that you should never expose fabric to an open flame such as a campfire or stove burner. However, even sitting a safe distance away from a campfire can be dangerous to your warm cozy sweater. Sparks are hot enough to melt holes in sweaters, blankets, and other items even 20 feet away.
Flammability Ratings for Fabric
What is a Flammability Rating
In many countries, including the US, there are laws in place that require fabrics to meet certain standards of flame resistance. Children’s sleepwear and fabric curtains have especially stringent standards. This is by no means a comprehensive list of laws in the US that regulate the fire resistance of fabrics, but it should give you a general idea of the protections the government enforces for household and clothing items.
The most universal regulation is probably the federal regulation “16 CFR § 1610.4 – Requirements for classifying textiles” that divides fabrics into classes based on whether they are safe to sell in the US or not. This regulation requires some fabrics to undergo a flammability test. The flammability test measures how a fabric burns after a one-second exposure to a flame. The test doesn’t measure whether or not the fabric will catch on fire; it tests how long it takes for the fire to spread, meaning that if your apron catches on fire in the kitchen, the fire should spread slowly enough to give you time to take off the apron before it seriously injures you.
Based on their potential flammability, fabrics are classified as Class 1 Normal Flammability, Class 2 Intermediate, or Class 3 Rapid and Intense Burning. Class 1 fabrics are safe for clothing, Class 2 are safe for non-clothing uses, and any fabric that is classified as Class 3 can’t be sold in the US.
Another part of this federal regulation that impacts consumers today is the “Code of Federal Regulations at 16 CFR Part 1615.” This law requires that any fabric meant to be used for children’s sleepwear meet very stringent fire-resistance standards. A different testing process ensures compliance with this regulation. This test is a bit more complicated and involves holding a sample of the fabric to a gas flame for three seconds, and measuring how far the flame spreads in the fabric sample.
Finally, the National Fire Protection Association (NFPA) uses a test called “NFPA 701: Standard Methods of Fire Tests for Flame Propagation of Textiles and Films.” Most public venues, especially ones that use stage curtains, must meet this standard. In some places, any curtain or drapery fabric also must meet this standard.
Non-Flammable Fabrics
While no fabric is truly 100% flame-proof, some fabrics are designed to be really difficult to burn. Fabrics like Nomex and Kevlar contain inherently flame-resistant fibers. The addition of a protective chemical coating makes this already flame-resistant fabric even tougher.
Unlike polyester, these specially designed protective fabrics will not melt at high heat. In fact, Kevlar’s burning point is 800℉!
What Fabrics are Most Flammable
Natural fibers like silk and cotton make the most flammable fabrics. Linen and cotton in particular burn very easily. While many synthetic fabrics have chemicals in their fibers that resist burning, most natural fibers are highly flammable.
Wool is a strong exception to this rule, though! Wool is a natural fiber that only burns at incredibly high temperatures. It doesn’t melt dangerously like most synthetics. Its dense weave prevents oxygen from lending strength to any fire that does reach it.
If you are wondering how other fabrics compare to polyester, here is a quick overview of the flammability of several well-known fabrics.
| Type of Fabric | Burning/Melting Point | Burns Easily | How it Burns |
| Cotton | 200℉ | Yes | Burns orange. Does not melt. Shrinks from flame. |
| Kevlar | 800℉ | No | Difficult to catch on fire and will self-extinguish once the heat source is removed. |
| Nylon | 428℉ | No | Will melt into plastic beads |
| Polyester | 482℉ | No | Difficult to burn but will melt once hot |
| Poly-Cotton | 356℉ | Yes | Resists flame but will burn and melt into a resin |
| Wool | 1058℉ | No | Very difficult to burn. Does not melt. |
What is Polyester’s Flammability Rating
As you can see from the chart above, polyester is quite difficult to burn. Due to its chemical structure, polyester meets the flammability requirements in the US without undergoing the flammability tests that some fabrics must pass. Since it is difficult to burn and self-extinguishes easily, polyester is grouped into the Class 1 fabrics that are safe to use for clothing. Polyester is often used for children’s sleepwear, which has very strict fabric requirements in the US.
Dos and Don’ts of Heat Printing on Polyester
Heat printing, or heat transfer printing, uses a heat press to imprint a design onto a surface. It is a popular way to decorate t-shirts and bags. Lots of crafty people have at-home heat presses so they can design their own shirts (Cricut has a popular model, for example.).
The key thing to remember if you want to use a heat press on a polyester item is that the temperature should remain below 300℉. The ideal temperature is typically 270℉. It’s a good idea to read the manufacturer’s label inside the item you are printing on to see if there are notes about its resistance to heat.
Some transfers require a longer time under the press, but it’s a good idea to limit the length of time you expose your polyester item to heat. If you can, cutting the heat press time down to ten minutes should prevent any possible melting or scorching. You might assume that using a thicker transfer pad will protect the polyester, but this will also slow the transfer of your design. Using a thinner transfer pad for a shorter time is safer.
Can Polyester Fabric Melt in the Dryer?
Have you heard the urban legend of the aunt (or sister, or cousin, or friend) who melted a polyester shirt into a hard lump of plastic in the dryer?
It is possible to melt polyester inside a dryer. It’s not very likely, though, so don’t panic if you get halfway out of your laundry room and realize you threw your favorite polyester blouse into the dryer along with the sheets and pillowcases. However, it is much more likely that your polyester clothing could warp or twist out of shape if it gets too hot in the dryer. It’s recommended to set your dryer on a low heat setting to protect polyester items.
Polyester is a quick-drying fabric, so you could also go green and hang your clothes to drip dry instead of running your dryer! There’s a great added benefit to air-drying polyester, too. Polyester has a real issue with the buildup of static cling; air-drying lets you avoid all the dryer static.
Iron Temperature Setting for Polyester
While dryers might typically be safe for polyester, irons are much more dangerous! Put your iron on the wrong setting, and it will melt straight through polyester. On top of that, sticky strings of melted polyesters will glob all over the base of your iron.
If you desperately need to iron your polyester clothing, take these safety measures:
- Check the settings on your iron. Most irons come with helpful descriptions on the heat dial, such as “cottons” and “polyester.” If your iron does not specifically say what kind of fabric each setting is for, just use the lowest possible heat setting or the “warm” setting.
- Read the manufacturer’s label on the item you want to iron. The labels often indicate whether or not it is safe to expose the fabric to high heat.
- Use a pressing cloth (any thin, heat-resistant fabric that you can place between your polyester fabric and the iron).
Polyester Safety Tips
Since you are reading this, you are already more aware of the pros and cons of polyester than most consumers! Here are a few general guidelines to keep you safe around polyester draperies, household items, and clothing.
Polyester Burns
Warning: this is kind of gross, so if you are feeling squeamish, please skip this section!
If the worst happens and polyester burns and melts onto you, don’t try to treat the burn yourself. Melted polyester can harden and fuse to your skin once it begins to cool. If you try to get the polyester off the burned area, you will probably damage the unburned skin underneath.
Here’s what you should do in this situation: get to running water as fast as you can and hold the burned area under cool water. This will prevent the polyester from continuing to melt and make the burn worse. Then head to the emergency room, where medical professionals can safely remove the polyester without damaging the healthy skin beneath the burn.
Deceptive Draperies
In order to meet legal requirements for flame-resistance, fabrics that are used for curtains are usually treated with special chemicals and are then certified as flame-retardant. Here’s the tricky thing, though, this certification often expires, sometimes within a year. This doesn’t mean your living room curtains are going to spontaneously combust any time soon, but it does mean that the protective chemical coating that would have prevented your curtains from burning quickly is no longer effective. You may want to consider re-treating your drapes yourself or hiring a professional.
Situational Awareness
Have you ever huddled into a nice, fleecy sweatshirt beside a campfire? If a spark floated out of the fire and landed on your fuzzy sweatshirt, you probably noticed that it melted a dime-sized black hole right into the surface of the shirt before you could flick that spark out of existence. Polyester is flame-resistant and is even considered one of the safest materials for children’s sleepwear because it burns so slowly. But because it melts, polyester can cause dangerous burns.
Some work environments that require protective clothing do not allow employees to wear polyester, even under their protective gear, because a loose spark could melt the polyester and cause an injury. Be aware of potential heat sources if you are wearing polyester.
Style Matters
It’s not a great idea to wear polyester or other synthetic fabrics, around a dangerous heat source. Additionally, the cut and style of your clothing can pose a greater risk than the nature of its fabric. Remember how fire loves thin, loosely woven fabrics that allow more access to oxygen? The same principle applies to your style of clothing. If you wear diaphanous, flowing robes around the house, you probably look very elegant, but the second you brush up against an open candle flame, you could be in big trouble!
Close-fitting clothes are usually safer than loose clothes. A sleek cut is safer than something dripping in ruffles, though there’s a time and a place! Who doesn’t love a pretty ruffle once in a while?
All this is not to say that you should avoid polyester in your house or in your clothing. Polyester is one of the most popular fabrics on the market, and it is much more fire-resistant than many natural fabrics. Now that you know what to look out for, you can keep yourself safe even if you enjoy wearing floor-length polyester skirts everywhere you go!
Conclusion
Polyester is an adaptable fabric that is commonly used in clothing and household items like upholstery and bedding. It’s important to know how to use this popular material safely! Did you find this information about polyester’s flammability helpful? Leave a comment below!