What is polyester?
Properties, limits and whether it is waterproof
Polyester is the most widely produced textile fibre in the world and accounts for 59 percent of global fibre output. What the name is allowed to mean is fixed by an EU regulation. This page gives the official definition, the measured figures, the reason polyester repels water without being waterproof, and the seven polyester qualities we actually work with.
Is polyester waterproof?
With a moisture regain of 0.1 to 0.4 percent, the polyester fibre is hydrophobic: it absorbs almost no water at all, where cotton takes up around 8.5 percent. A fabric woven from that fibre is nevertheless not waterproof, because water passes between the yarns rather than through them. So the honest answer to "is polyester water resistant" is yes, and to "is it waterproof" no. Water repellent and waterproof are two separate properties, each with its own test standard, set out on What is waterproof?.
Only a backing, a coating or a laminate closes the weave. Our Cover-PVC is exactly that: a polyester fabric with a PVC coating that reaches 4,000 mm hydrostatic head, the highest value in our range. How that millimetre figure is measured is explained on What is water column?.
What repels water attracts grease. Polyester is hydrophobic and oleophilic at the same time, meaning it absorbs oils and holds on to them. For outdoor cushions that means the problem is not rain but sunscreen, barbecue grease and skin oils. Treat those stains immediately, before they settle in.
What polyester is, and what it is not
The name is not a marketing term but a protected fibre designation. Anyone printing it on a label is making a statement about chemistry and is bound by it.
The official definition
EU Regulation 1007/2011 on textile fibre names lists polyester in Annex I under number 35: a fibre formed of linear macromolecules whose chain consists of at least 85 percent by mass of an ester of a diol and terephthalic acid. The name is therefore tied to a chemistry, not to an appearance. In practice it is almost always polyethylene terephthalate, PET for short, the same polymer family as drinks bottles.
Fleece is not a fibre
Fleece describes a brushed knit, which is a type of fabric. It is usually made of polyester but is not itself a fibre name. The same goes for polycarbonate: it has no entry at all in Annex I and does not meet the definition. Lists mixing these up are common online and confuse fibre with finished goods.
Where the fibre came from
The first viable polyester fibre was developed in 1941 by the English chemists John Rex Whinfield and James Tennant Dickson under the name Terylene. From 1951 it was sold in the United States as Dacron. Today polyester is the most produced fibre of all and has long overtaken cotton.
Why the label has to state it
The same regulation governs textile labelling and requires the fibre composition to be declared before purchase, not only on the product itself. That is why every fabric in our shop carries its composition as a percentage rather than just a material name.
Polyester properties, the measured figures
These values describe the polyester material itself, not the finished fabric. They come from the CAMEO materials database of the Museum of Fine Arts Boston, which bases its entries on standard textile references. The ranges are not measurement error: polyester is not a single product, and titre, cross section and finish differ considerably.
| Property | Polyester (PET) | What it means in practice |
|---|---|---|
| Moisture regain | 0.1 to 0.4 percent | the fibre absorbs almost no water, cotton sits at around 8.5 percent |
| Melting point | 238 to 290 degrees Celsius | heat sensitive, which rules out the tumble dryer and a hot iron |
| Density | 1.23 to 1.38 g/ml | light, so a cover stays manageable even when wet |
| Tenacity | 2.2 to 9.5 g/denier | high tensile strength, dimensionally stable, resists creasing |
| Elongation at break | 10 to 50 percent | elastic enough that seams on cushions do not tear straight away |
| Behaviour in fire | difficult to ignite, self-extinguishing | burns with a sooty flame and goes out once the flame is removed |
| Chemical resistance | resists weak acids, weak alkalis and bleach | tolerates cleaning; strong alkalis and strong acids attack it |
Where polyester reaches its limits
The fibre is robust but not indestructible. Three properties decide where we use polyester and where we recommend acrylic instead.
Direct sunlight breaks the fibre down
Polyester degrades in direct sunlight. That is degradation of the fibre itself, not of the dye. This is why a solution-dyed polyester fabric in permanent sun does not last as long as a solution-dyed acrylic, even though both reach a similar lightfastness rating. Colour stability and material stability are two different things.
Static charge
Polyester builds up static electricity and attracts dust as a result. Indoors this is more noticeable than outdoors, where rain and wind rinse the surface anyway.
What polyester does particularly well
The fibre resists insects and microorganisms. Moths do not eat it, and it offers mould no nutrient base of its own. Together with the very low moisture regain, that is why polyester is the first choice for covers and protective hoods.
How the dyeing method comes into it
If the pigment is added to the melt instead of dyeing the finished fabric, it sits inside the fibre rather than on it. That raises colour fastness considerably but changes nothing about UV degradation of the fibre. The method is explained on What is solution dyed?.
Polyester fabric in our range, seven qualities
Seven fabrics in our programme are made of polyester, with very different jobs to do. It shows how little the word on its own says about a fabric.
| Fabric | Weight | Distinctive feature | Used for |
|---|---|---|---|
| Polysun | 260 g/m² | solution dyed, water repellent, spray test 4 out of 5 | sun protection, awnings, shade sails |
| Cover-PVC | 280 g/m² | PVC coated, 4,000 mm hydrostatic head | covers and protective hoods |
| swela vuscreen Livorno | approx. 350 g/m² | screen weave with a 3 percent openness factor | outdoor curtains, privacy with a view through |
| Cord 5 mm | 386 g/linear m | anti-stain finish, machine washable at 40 degrees | indoor upholstery |
| Cord 25 mm | 400 g/m² | wide rib, hand wash only | indoor upholstery, wall cushions |
| Velvet | 250 g/m² | pile fabric, hand wash only | indoor upholstery, decorative cushions |
| Teddy-Bear | 380 g/m² | high pile, hand wash only | indoor cushions, dog beds |
How to clean polyester
The fibre tolerates a lot, the finish on top of it does not. Four rules apply across all our polyester qualities.
30 degrees at most, often hand wash only
Of our fabrics only Cord 5 mm goes in the machine, at up to 40 degrees. Polysun, Cord 25 mm, velvet, Teddy-Bear and Cover-PVC are hand wash only, because drum movement and spinning damage the surface and, on coated qualities, the coating itself. The screen weave is simply rinsed with a water jet, never a pressure washer.
No bleach, no iron, no tumble dryer
Bleach attacks the finish. Ironing and tumble drying are ruled out by the melting point: the fibre deforms and on laminated qualities the layer separates. Polyester dries quickly in the air anyway, precisely because it takes up so little water.
Deal with stains immediately
Because of the affinity for oils, time is the decisive factor. Apply a neutral soap solution with a soft cloth in gentle circular movements, then rinse with clean water. Use stain removers sparingly and test them on a hidden area first.
Do not apply your own waterproofing
Products applied afterwards can react with the factory finish and make the water repellency worse rather than better. If beading falls off, ask us which product suits that specific fabric.
Frequently Asked Questions
Sources
- Regulation (EU) No 1007/2011 of the European Parliament and of the Council of 27 September 2011 on textile fibre names, Official Journal L 272/1. Annex I number 35 carries the official definition of polyester (archived copy, the original blocks crawlers)
- CAMEO, Conservation and Art Materials Encyclopedia Online of the Museum of Fine Arts Boston, entry Polyester fiber. Figures for moisture regain, melting point, density and behaviour in sunlight, sourced from standard textile references
- Textile Exchange, Materials Market Report 2025, cited via the European Commission transition pathway pages. Polyester at 78 million tonnes and a 59 percent market share in 2024
- What is waterproof? The distinction from water repellent, with both test standards
- All fabrics at Germes with their technical values
Last reviewed: 24.08.2026 · Reviewer: Germes-Team
Polyester or acrylic, which one suits your site?
Tell us where the fabric will be used, how much sun it gets and whether it is allowed to get wet. We will tell you which fibre makes sense there and which quality fits.