Polyester
The world's most used fibre. A petroleum-based plastic (PET) melt-spun into filaments. It's light, strong, quick-drying and cheap, which is why most running gear is made from it.
How it’s made
- 1PET is polymerised from petrochemicals (terephthalic acid and ethylene glycol) and formed into chips.
- 2The chips are melted and extruded through spinnerets into continuous filaments.
- 3Filaments are textured, or cut into staple fibre for blending, then knitted or woven. Knit structure largely decides how it handles sweat.
What to look for
- Recycled content where possible (see recycled polyester)
- Knit structure made for moisture transport, such as mesh zones or bi-component knits
- Odour treatments: some rely on silver or other biocides, which you may want to avoid
Pros
- Quick drying
- Strong and shape-stable
- Inexpensive
Cons
- Holds body odour
- Sheds microfibres when washed
- Fossil-based and not biodegradable
Typical use
- Running:
- Singlets, shorts, jackets.
- Streetwear:
- Track jackets, fleece, blends with cotton.
Sustainability
Fossil feedstock and microfibre shedding are the main issues. Recycled polyester lowers the virgin input but not the shedding.