Overview - EN ISO 1889:2009 (Reinforcement yarns - Determination of linear density)
EN ISO 1889:2009 specifies a laboratory test method to determine the linear density (mass per unit length) of reinforcement yarns used in composites. It applies to glass-fibre, carbon-fibre, aramid-fibre and other reinforcement-fibre yarns, including single, double/cabled, textured yarns, rovings and staple-fibre yarns. The standard defines required apparatus, specimen selection, conditioning, desizing procedures and the calculation used to report linear density (typically expressed in tex, where 1 tex = 1 g/km).
Key topics and technical requirements
- Principle: Weigh a yarn specimen of known length and calculate linear density using Tt (g/km) = 1000 × m (g) / L (m).
- Specimen selection: Lengths depend on nominal linear density (tex). Example ranges from 500 m for very fine glass yarns (<25 tex) down to 5 m for very coarse glass rovings (>2 000 tex). Carbon and aramid specimens may be specified by minimum mass (e.g., carbon: mass > 0.25 g for fine yarns; aramid: mass between ~3 g and 10 g).
- Apparatus: calibrated spool (or cutting device for short specimens), analytical balance (0.1 mg resolution), forced‑circulation oven (105 ± 3 °C), muffle furnace for glass (≈625 °C), Soxhlet extractor or pyrolysis equipment for carbon, desiccator, tweezers and weighing bottles.
- Desizing / pretreatment:
- Glass: calcination in a muffle furnace (removes sizing).
- Carbon: extraction (Soxhlet) or pyrolysis (nitrogen) per ISO 10548.
- Aramid: solvent extraction (Soxhlet) and drying.
- Conditioning and atmosphere: Tests are carried out in a standard atmosphere per ISO 291; aramid yarns require (20 ± 2) °C and (65 ± 5) % RH if sized.
- Reporting: Include method used (desized, dried sized, as-received), specimen length/number/location, individual results and test details. Precision from interlaboratory studies is not provided in the standard.
Practical applications and users
- Quality control and acceptance testing for manufacturers of reinforcement yarns and composite reinforcements.
- Materials and process engineers specifying yarn properties for composite part design (automotive, aerospace, wind energy, sporting goods).
- Testing laboratories verifying product specifications and batch consistency.
- Procurement and certification teams requiring standardized linear density data for supplier evaluation.
Related standards (normative references)
- ISO 291 - standard atmospheres for conditioning and testing
- ISO 1887 - textile glass - determination of combustible-matter content (desizing/calcination reference)
- ISO 3344 - determination of moisture content for reinforcement products
- ISO 10548 - carbon fibre - determination of size content (extraction/pyrolysis methods)
Keywords: EN ISO 1889:2009, linear density, reinforcement yarns, glass-fibre, carbon-fibre, aramid-fibre, tex, test method, desizing, conditioning, Soxhlet extractor, muffle furnace.
