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All About Polyester Threads

All About Polyester Threads

02 February 2024

Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in plants and insects, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not. Synthetic polyesters are used extensively in clothing.

Synthetic fibers using polyester have high water, wind, and environmental resistance compared to plant-derived fibers. They are less fire-resistant and can melt when ignited. Polyester fibers recover quickly after extension (the term elongation describes the stretch and recovery) and absorb very little moisture. Polyester is heat resistant (dryer and iron safe), with a melting temperature of about 480º F (in comparison, nylon starts to yellow at 350º F and melts at about 415º F). Polyester fibers are colorfast, resistant to chemicals, and can be washed or dry-cleaned with most common cleaning solvents.

Main types of polyester thread

Spun Polyester Sewing Thread

Spun polyester sewing threads are made by spinning or twisting together shorter lengths of polyester fibers. This is similar to the way cotton threads are made. These short fibers are then twisted together to produce a thread of the desired size. Spun polyester threads give the look of a cotton thread, but have more elasticity. Spun polyester is economical to produce and is usually a low-cost thread. 

Polyester Corespun Sewing Thread

Polyester corespun threads, also referred to as Poly-poly sewing threads, are a blend of spun polyester wrapped around a filament polyester core. One notable advantage of utilizing these threads is the increased strength provided by the filament core. With their matte finish and impressive tensile strength, corespun polyester threads have become a beloved choice for quilting enthusiasts.

Bonded Polyester Sewing Thread

Bonded Polyester is a strong polyester thread used for upholstery applications. Since polyester has fantastic UV resistance, bonded polyester is commonly used for outdoor furnishings and automotive upholstery. A special resin coating adds strength and helps reduce friction when stitched at high speeds.

Filament Polyester Sewing Thread

Filament polyester is a continuous fiber thread. Some hear the word filament and incorrectly assume it is monofilament. Monofilament, which looks like fishing line, is just one type of filament thread. It is a single strand thread. Other filament threads are multiple filaments, which consist of two or three strands twisted together. This is the largest category of filament polyester. Multi-filament strands are smooth and lint free but are not transparent. The advantage of a lint-free thread is a cleaner machine and less maintenance. 

Trilobal Polyester Embroidery Thread

Trilobal/Triangle polyester is a multiple filament, twisted, high-sheen continuous fiber thread. It has the bright appearance of rayon or silk, but the advantages of a polyester fiber. Triangular shaped fibers reflect more light and give an attractive sparkle to textiles.