XM-50 28S/2 is a flame-retardant sewing thread spun from 80% meta-aramid and 20% polyester staple fibre. The 28S/2 two-ply construction is built for lighter FR fabrics and linings, combining the meta-aramid’s non-melting, permanent flame resistance with the seam strength and sewing performance of a polyester-blended thread.
Meta-aramid’s flame-retardant property comes from the polymer itself, so the thread will not melt or drip and its FR performance is permanent. XM-50 has been independently tested by AITEX (Spanish Textile Research Institute, ENAC-accredited laboratory) against the sewing thread requirement of EN 61482-2:2020 — the European standard for protective clothing against the thermal hazards of an electric arc — and additionally tested for colour fastness to laundering, light and rubbing, and for limited flame spread to EN ISO 15025.
Test method: EN ISO 3146:2000 Method B (Differential Scanning Calorimetry per EN ISO 11357-3:2025)
Pass criterion: No melting at 260 °C ± 5 °C
XM-50 result: No melting observed across the full test range up to 300 °C
Report reference: AITEX 2026EP1658 (issued 23 April 2026)
This certifies XM-50 as suitable for use in structural seams of protective clothing built to EN ISO 11612 (heat & flame), EN ISO 11611 (welding), EN 469 (firefighter clothing) and arc-flash EN 61482-2:2020. XM-50 also holds OEKO-TEX® Standard 100 certification, verifying it is free from harmful substances and safe for prolonged skin contact.
Key performance
Does not melt — verified to 300 °C in DSC testing
Colour fastness to laundering: colour change grade 5, staining (polyamide/cotton) grade 4-5
Colour fastness to light: grade 3-4
Colour fastness to rubbing: grade 4-5 (dry and wet)
Limited flame spread (EN ISO 15025): pass — no flame to top or side edge, no melting, no hole formation
Typical applications
Structural seams in lighter-weight flame-retardant garments and linings:
- firefighter station wear
- industrial and utility FR workwear
- welder’s clothing
- military combat uniforms
