Manufacturer · Fashion & Home Accessories
Cotton or polyester thread – the choice depends on the fabric and the load. Polyester is stronger, more elastic and does not shrink, so it is more durable in most garments. Cotton is better for natural fabrics, high-temperature ironing and garments that are dyed after sewing.
The main difference between cotton and polyester thread
Cotton is a natural cellulose fibre. Thread made from it is soft, matte and stable, but stretches little and weakens with prolonged exposure to moisture and sunlight. Polyester is a synthetic fibre – it is made as a continuous filament or as spun staple fibre and twisted into thread. It is smoother, more elastic and hardly reacts to washing.
There is also a third option – a thread with a polyester core wrapped in cotton or polyester fibres (core-spun). It takes the strength of polyester and the matte look of cotton and is the standard in the production of jeans and workwear.
Cotton or polyester thread – a comparison of properties
| Property | Cotton thread | Polyester thread |
|---|---|---|
| Strength at the same thickness | lower | higher |
| Elongation (elasticity) | low | considerable |
| Shrinkage in washing | slight shrinkage possible | practically does not shrink |
| Ironing | withstands the highest temperature | may melt under an iron that is too hot |
| Dyeing after sewing | takes up the dye together with the cotton | stays in its original colour |
| Resistance to sunlight and moisture | lower | high |
| Lint in the machine | more | little |
| Look of the seam | matte, natural | smooth, with a slight sheen |
Which thread is more durable in real use
The durability of a seam depends on more than the thread material. The stitch type, the stitch length, the needle and the fabric itself all matter. Still, there are clear patterns:
- Under stretch, polyester wins hands down. A cotton seam on knitwear breaks the first time the garment is put on.
- Under abrasion – pockets, crotch, sleeve edges – polyester and core-spun thread last longer.
- With frequent high-temperature washing, cotton keeps its look but weakens over the years, while polyester hardly changes.
- Outdoors and in the sun, cotton loses strength faster – that is why awnings, backpacks and outerwear are sewn with polyester.
There is a flip side: a thread that is too strong on a delicate natural fabric can tear the fabric instead of the seam giving way. With fine silk, batiste or old linen, a softer cotton seam is sometimes kinder to the item.
The way the polyester thread is made also matters. Spun (staple) polyester has a soft, slightly matte look and behaves similarly to cotton in the machine. Continuous filament thread is smoother, stronger and shinier. Core-spun threads combine both approaches. So when comparing, it is not enough to say “polyester” – ask about the thread construction, the thickness and its intended use before approving it for a production run.
When to choose cotton thread
- you sew cotton, linen or wool and want the fabric and seam to react in the same way;
- the item will be dyed after sewing;
- the garment is ironed very hot or washed at 60–90 °C;
- you want a matte, natural look for the seam;
- the collection focuses on natural materials.
See the available options in the cotton threads category.
When to choose polyester thread
- knitwear, sportswear, lingerie and fabrics with elastane;
- trousers, jackets, coats and workwear;
- synthetic and blended fabrics;
- bags, backpacks, outdoor products;
- high-speed series production, where fewer breaks and stoppages matter.
- items that are washed often at low temperatures and must keep their seams for years.
- labels and accessories sewn onto a synthetic base.
Polyester and core-spun options can be found in the sewing threads range.
Common mistakes when choosing
- Cotton thread for knitwear. The seam looks fine until the garment is worn for the first time.
- Polyester thread for a garment that will be dyed. After dyeing, the seams stay white and stand out.
- Different threads in the needle and the bobbin. The shrinkage differs and the seam puckers after the first wash.
- Cheap polyester thread of uneven thickness. The material alone does not guarantee quality – breaks and knots come from poor manufacturing.
How to test the thread before you choose
Tables give a direction, but the final decision is best made after a test on the actual fabric. One simple check in the factory saves complaints later:
- Sew two identical samples – one with cotton, the other with polyester thread, with the same needle and stitch length.
- Stretch the seam across and along. If the fabric is elastic, the cotton seam will give way first.
- Wash the samples at the temperature on the care label and iron them.
- Compare whether the seam has puckered, whether the colour has faded and what the surface of the thread looks like.
- For garments to be dyed, dye both samples and see how the seam takes the colour.
Also pay attention to the machine. Polyester produces less lint and breaks less often at high speed, which is important for long runs. Cotton requires more frequent cleaning around the hook area, but gives a softer, more natural seam.
How to order threads from Polkom
Polkom is a manufacturer of accessories for fashion, furniture, footwear and bags, based in Sofia and delivering across the EU. If you are not sure whether cotton, polyester or core-spun is better for your item, describe the fabric and the types of seams – we will suggest a specific article and a sample. Write to us via Contact.
