SERAFLEX® Stretch Thread – All Colors, 142yds | Mettler

Sew knits with a straight stitch — no zigzag required. Mettler SERAFLEX® is a high-performance elastic sewing thread engineered for stretch fabrics. Its PTT fiber composition allows elongation up to 65%, giving seams roughly twice the elasticity of standard threads. Choose your color below; every review on this page covers the same thread.

Color options: 7 colors in stock
Length / Weight: 142 yds / 50wt per spool
Fiber: 100% PTT (elastic polymer)
Treatment: Chlorine-resistant — safe for swimwear and frequent washing
Certification: STANDARD 100 by OEKO-TEX®; manufactured to internationally recognized ecological requirements

Perfect for: swimwear, knits and activewear, lingerie, kids' clothing, sportswear and outdoor gear — any seam that needs to stretch.

❓ Frequently Asked Questions

How do I sew with SERAFLEX?

Use straight stitches only, thread it in both the needle and bobbin, and reduce thread tension to a minimum to fully activate its elasticity.

Can I use it for swimwear?

Yes — SERAFLEX is chlorine-resistant, making it an excellent choice for swimsuits that see pool time.

Why use it instead of a zigzag stitch?

SERAFLEX lets a plain straight stitch stretch with the fabric — a cleaner-looking seam with about twice the elasticity of standard thread.

Does it work in a regular sewing machine?

Yes — any machine that sews a straight stitch, no special equipment needed.