Bonded polyester thread in size 138, commonly identified as 420D/3, is a strong, durable sewing thread designed for demanding applications. Its three-ply construction combines three strands of 420-denier polyester, while the bonding process helps keep the plies together during sewing.
Key Benefits
- High strength: Suitable for seams that must withstand tension and repeated use.
- Abrasion resistance: Performs well on materials exposed to friction and handling.
- Moisture resistance: Polyester retains its performance in humid or outdoor conditions.
- Reduced untwisting: The bonded finish supports cleaner stitching and helps minimize fraying.
- Color durability: Quality polyester thread offers good resistance to fading.
Common Applications
Bonded polyester 138 / 420D / 3 is often used for upholstery, automotive interiors, outdoor furniture, awnings, boat covers, luggage, bags, footwear, leather goods, and heavy-duty textile products.
Sewing Considerations
Use a machine, needle, and tension settings suitable for heavy-duty thread. Always test the thread on the intended material first, because the ideal needle size and stitch length depend on the fabric, coating, seam construction, and machine. Store the thread in a clean, dry place away from direct sunlight.
Conclusion
For projects requiring durable, neat, and weather-resistant seams, bonded polyester 138 / 420D / 3 is a practical choice. Its strength and stable construction make it suitable for both industrial sewing and high-performance textile applications.