What is Polyester?

Polyester is a fiber made from a long-chain synthetic polymer; Pratt Institute calls it one of the most widely used fabrics in the world. Fiber-naming rules used for labeling define polyester by its chemical structure. According to the EU textile fiber names regulation (1007/2011, Annex I, no. 35), polyester is a fiber made of linear macromolecules containing in the chain at least 85% by mass of an ester of a diol and terephthalic acid. The US Federal Trade Commission rule (16 CFR 303.7) likewise requires a long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalate units. Polyethylene terephthalate (PET), an ester of ethylene glycol (a diol) and terephthalic acid, falls within this definition.

These definitions are taken from texts in force at the date of this entry (October 2026). For the fiber name and percentage declaration on a label, check the current rules of the market you sell in, and consult a specialist if needed.

How polyester is made and what forms it comes in

Polyester is made from petroleum-based raw materials by polymerization (Pratt Institute). Synthetic filaments are produced by extruding plastic chips through a spinneret, a die with fine holes (Cotton Incorporated, Textile Yarns).

• Continuous filament: Filament yarns are generally smoother, shinier and more even, and less absorbent. When the filament is textured, luster falls; stretch, bulk and softness rise, and moisture wicking improves (Textile Yarns).
• Staple (cut) fiber: Filaments from many extrusion heads are gathered into a bundle called tow, crimped and cut to short lengths. These cut fibers can be blended with fibers such as cotton and spun into blended yarns (Textile Yarns).

Properties

• Strength and care: Pratt Institute describes polyester as a strong, durable fiber that resists shrinking, stretching and creasing, dries quickly and is easy to care for.
• Thermal behavior: Polyester behaves as a thermoplastic at high temperature. In thermosol dyeing with disperse dyes the fabric is fixed at 200–220 °C; at this temperature the fiber becomes thermoplastic and the dye enters the fiber (Sukanya Devi, e-PG Pathshala). According to Cotton Incorporated, thermoplastic synthetics can be heat-set while cellulosic fibers cannot, and synthetic fibers also do not show cotton’s swelling-shrinking behavior (ISP 1009).
• Moisture behavior: Cui et al. (2025) classify polyester filament as hydrophobic and cotton yarn as hydrophilic. According to the same study, hydrophilic fibers absorb moisture well but are poor at transporting and releasing it, and hydrophobic fibers show the opposite. Pratt Institute gives moisture wicking as a reason polyester is preferred in sportswear.
• Pilling: In the introduction to their study on three-thread fleece fabric, Hossain et al. (2021) report, citing earlier work, that adding polyester to a fabric increased pilling and that polyester’s electrostatic properties can seed pill formation. Read this as a tendency, not a certain result for every fabric.
• Sublimation printing: The disperse dyes used in sublimation (heat transfer) printing most readily color fibers such as acetate, polyester, acrylic and nylon (Sukanya Devi, e-PG Pathshala). According to a garment distributor’s guide, in blends with less than 65% polyester the dye does not bond to cotton and washes out over time (SanMar U, 2024).
• Environment: Polyester is petroleum-based and does not biodegrade. Its production is energy-intensive, and it can release microplastics in washing (Pratt Institute).

Recycled polyester

Pratt Institute notes that recycled polyester is often obtained from post-consumer plastic bottles. For standards such as GRS that document recycled-content claims, see the textile certifications guide.

Telling polyester from cotton and viscose

Polyester is a petroleum-based synthetic fiber; cotton is a cellulose-based natural fiber. Viscose (rayon) is also cellulose-based, but it is a man-made fiber produced by chemically modifying cellulose, and it is not petroleum-based (CottonWorks, Natural vs. Synthetic Fibers). In cotton-polyester blends, polyester can improve dimensional stability: Hossain et al. (2021), citing another source, report that polyester-cotton blended garments are more durable and less likely to deform and shrink; in return, pilling tendency rises (see above).

In a quotation, state the form of the fiber (filament or staple), the blend percentage and, if a recycled-content claim is made, its certificate. You can find staple polyester fiber suppliers in the Textile Fibers category and polyester yarn suppliers in the Polyester Yarn category.

Frequently asked questions

Does polyester breathe?

Polyester absorbs very little moisture but transports it well; Pratt Institute stresses its moisture wicking, and Cotton Incorporated notes that textured filament improves wicking. Breathability and moisture management are determined not only by the fiber but also by yarn and fabric structure, so evaluate a sample in its conditions of use.

Can you print on polyester T-shirts?

Yes; the method depends on composition. The disperse dyes used in sublimation color synthetic fibers such as polyester (Sukanya Devi, e-PG Pathshala), so sublimation suits high-polyester fabric. According to a distributor’s guide, the dye does not bond to cotton, and below 65% polyester the print fades in washing (SanMar U, 2024). For a comparison of methods, see our textile printing methods guide.

Why is polyester blended with cotton?

The blend combines polyester’s dimensional stability and durability with cotton’s moisture absorption and comfort (Hossain et al., 2021; Cui et al., 2025; ISP 1009); the price is a higher tendency to pill. For fabric selection, see the fiber table in the T-shirt fabric types guide.