Polyester thread's natural UV resistance makes it the first choice for anything used outdoors on a regular basis. It looks, feels, sews and performs like nylon and can be used anywhere nylon thread is used.

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Polyester Thread

When To Use Polyester Thread - Polyester thread looks, feels, and sews like nylon. You cannot tell the difference just by looking, and technical specifications like strength and stretch are very similar. This means that polyester works just as nylon in most applications including: upholstery, leatherwork, auto interiors, banners and flags, sports gear, dog collars, horse saddles and tack, knife sheaths, gun holsters, fishing lures, and brief cases.
Polyester does better than nylon when you are sewing things that have prolonged exposure to sunlight (UV rays), mildew, bleaching, acids, and alkalis. This means that it is a better choice for sewing anything that is going to be used outdoors most of the time. Pool covers, tarpaulins, outdoor furniture, banners, and flags are examples of things that should be sewn with polyester thread.

Pool Covers


Outdoor Furniture



It is important to distinguish between prolonged and occasional use. For example, a tent used for annual camping trips could be sewn with either nylon or polyester; a tent used to house a field operation for a season should be sewn with polyester. Similarly dog leashes, saddles, motorcycle seats, and boots can be sewn with nylon or polyester because they spend most of their time indoors.

Polyester thread does not provide the ultimate sunlight (UV) resistance. Pricey, plastic-looking brands like Sunbrella and Tenara come with replacement guarantees will out perform regular polyester. Also, there are UV treated nylon and polyester threads that do better. None of this matters if the material sewn is not equally bleach and sunlight resistant. After all, the material makes up at least 90% of the content and cost of the item that is being sewn.

There are times when polyester thread should not be used:

Fire retardant garments and gear - Polyester thread sticks at 440F and melts at 483F. This is too low for any application where thread and material must withstand high temperatures. Use Kevlar, Nomex, and PTFE Fiberglass threads in these situations. Kevlar and Nomex are heat resistant to 700F and do not melt; PTFE fiberglass protects to 1,000F.
Critical need for strength - Polyester thread is strong enough for the kinds of applications described so far. But, it is a bad choice for high stress applications such as conveyer belts because it can stretch up to 26% before it breaks. Size-for-size Kevlar Thread is about twice as strong and much more expensive than polyester or nylon. For example, Size 92 polyester has a 14.5 pound tensile strength; Kevlar in that size has a 30 pound tensile strength. Also, Kevlar only stretches 5% before it breaks.

Technically, our polyester thread is called filament polyester. It should not be confused with these other polyester threads:

Polyester Embroidery Thread - Polyester is rapidly replacing rayon as the first choice for embroidery. It is known for high sheen and standing up to washing and bleach. We have many polyester embroidery threads on our Embroidery and Sewing page and feature Robison-Anton Super Brite Polyester in about 400 colors.
Spun Polyester - Much of the thread used for sewing garments is spun polyesters sold under names like Perma Core and Maxi Lock. Spun polyester has a hair-thin polyester filament wrapped in cotton. It looks, feels, and sews like cotton and is surprisingly strong.  We have Robison-Anton Spun Polyester 700-yard mini spools for $1.50 and a Spun Polyester Grab Bag of partial spools for $2 a pound.
Factoid - Telling The Difference - Reading the label is always the best way to tell if a thread is nylon or polyester. If there is no label, you can tell by burning the thread in a safe, well ventilated area. Nylon thread (left) burns cleanly and leaves a gray ash. Polyester thread (right) burns brighter, has a foul odor that should not be breathed, and leaves a gooey plastic-like residue.

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