Manufacturer · Fashion & Home Accessories
UV resistant threads are synthetic threads that retain their strength and colour when exposed to prolonged sunlight. Most commonly, these are polyester threads with UV stabilizers and durable dyes, and for the most demanding outdoor conditions – PTFE (Teflon) thread. They are used for dashboards, seat uppers, cabriolet roofs, awnings and boat upholstery.
What sunlight does to thread
Ultraviolet rays break the molecular chains in synthetic and natural fibres. This process is gradual and initially invisible. First, the colour fades, then the thread surface becomes matte and rough, and finally it loses much of its strength and breaks under normal stress. A typical case is a seat or awning where the material looks fine but the seams fall apart – the thread is thinner than the fabric and absorbs light from all sides, so it degrades faster.
Car glass blocks some UV radiation but not all. Also, behind the glass, temperatures easily exceed 70–80 °C on the dashboard, and heat accelerates ageing. Therefore, even visible interior seams require thread with good lightfastness.
Which threads are UV resistant
Polyester
Polyester naturally withstands sunlight significantly better than polyamide and cotton. For most visible seams inside the cabin, quality polyester thread with durable dye is sufficient.
UV stabilized polyester
UV absorbers and stabilizers are added during thread production or coating. Such threads are used for cabriolet roofs, awnings, tents, boats and garden furniture – anywhere the product is directly exposed to sunlight.
PTFE (Teflon) thread
Fluoropolymer thread practically does not degrade from UV rays or chemicals. It is the most expensive option and is used for products that must withstand outdoor exposure for many years without seam replacement – marine awnings, tents and boat covers.
Polyamide (nylon)
Bonded polyamide is very strong but loses strength faster than polyester under prolonged sunlight. It is excellent for hidden and interior seams but is not the first choice for areas exposed to direct light.
Comparison of UV resistant threads
| Thread Type | UV Resistance | Typical Use |
|---|---|---|
| Cotton | Low | Not recommended for interiors or outdoor products |
| Bonded polyamide | Moderate | Interior seams of seats, doors, armrests |
| Polyester | Good | Visible seams in cabin, steering wheels, seats |
| UV stabilized polyester | Very good | Dashboards, cabriolets, awnings, boats |
| PTFE | Exceptional | Marine and permanently outdoor products |
Where UV resistant thread is needed in a vehicle
- Dashboard – the most sun-exposed surface with the highest temperature.
- Upper door panels and rear shelf behind back seats – exposed to direct sunlight through side and rear windows.
- Upper parts of backrests and headrests – especially with panoramic roofs.
- Cabriolet roofs and roof covers – directly outdoors.
- Steering wheel – exposed to sunlight through the windshield daily.
For these areas, choose thread from the automotive industry threads range and specify that the seam will be exposed to direct sunlight.
Colour fastness: a separate parameter
Strength and colour fastness do not always go hand in hand. Thread may retain its strength but fade from red to pink. Colour fastness is tested by standardized methods (e.g. ISO 105 series) and rated on a scale. Dark and neutral colours usually perform better than bright reds, oranges and yellows, which are popular for contrast seams. If you use a bright colour in a cabriolet, choose UV stabilized polyester and request a sample for comparison.
How to tell if a seam is sun damaged
When inspecting an old seat, awning or cabriolet roof, look for several signs. The thread is visibly lighter than the same thread in hidden areas, its surface is matte and fuzzy, and light scratching with a fingernail causes fibres to break apart. Another sure sign is when the seam breaks in several places simultaneously while the surrounding material remains intact. In such cases, repairing only one spot is pointless – all seams in the exposed area must be replaced with UV resistant thread, or neighbouring sections will soon tear as well.
How to extend seam life
- Use UV resistant thread only where needed, and for hidden seams choose more economical bonded polyamide.
- Do not use thread that is too thin for outdoor products. Thicker thread contains more material and maintains function longer.
- Cover the vehicle or boat when not in use. Covers protect both fabric and seams.
- Clean with products recommended for the material. Harsh solvents can damage thread coatings.
- Order thread from a single batch for the entire product to avoid shade differences that become visible after ageing.
UV resistant threads beyond automotive
The same principles apply outside automotive. For outdoor workwear, beach awnings, backpacks and tents, polyester thread is also a better choice than cotton. For ordinary garment seams see sewing threads, and for the full range – all threads.
UV resistant threads from Polkom
Polkom is a manufacturer of accessories for fashion, furniture, footwear and bags based in Sofia with over 30 years of experience. We supply polyester and UV stabilized threads for automotive upholstery, cabriolets and outdoor products, match colours by sample and send test samples. Minimum order quantities depend on the article. Send an inquiry via Contacts and describe where the seam will be exposed.
