Overview
ISO 6741-1:1989 - Textiles - Fibres and yarns - Determination of commercial mass of consignments - Part 1: Mass determination and calculations - defines standardized procedures for calculating the commercial mass of homogeneous consignments of single-species textile fibres and yarns. The standard is intended for independent third-party checks or when the commercial mass is to become the invoice mass. It does not apply to beamed or coated yarns, retail-packaged products, or fibre blends.
Key topics and technical requirements
- Scope and exclusions: Applies only to homogeneous consignments composed of a single generic species (see Part 4 for species list); excludes beamed/ coated yarns, retail packs and blends.
- Sampling principles: Describes total and partial sampling methods and how many containers to select depending on consignment size and variability. Reserve samples are recommended. (See ISO 6741-2 for sample assembly methods.)
- Weighing accuracy: Specifies weighing instrument accuracies - for containers (~0.1%) and for laboratory samples (0.05%) - and procedures for gross, tare and net mass determination.
- Laboratory samples and test specimens: Procedures for assembling, sub-dividing and sealing samples in air‑tight, low-hygroscopicity vessels for transport and test work.
- Cleaning and extraction: Cleaning options (washing, solvent extraction or pyrolysis) are referenced; selection of method must be agreed between parties (see ISO 6741-3).
- Drying and oven requirements: Table of drying conditions for specific fibres (temperature and duration) is provided; ovens must meet airflow and atmosphere requirements. Note: forced‑air ovens are restricted for acrylic fibres. The second edition revised the drying temperature for silk.
- Calculations: Defines how to compute commercial mass from dry or cleaned-dry mass by applying commercial moisture regain or commercial allowance values. Includes the “correction factor” calculations and statistical checks to ensure sampled containers are sufficient.
- Reporting: Requires documentation of methods used (sampling, cleaning, drying) and calculated results.
Applications and users
ISO 6741-1 is used by:
- Third-party inspection bodies and laboratories performing independent mass checks
- Textile manufacturers and exporters establishing invoice mass
- Importers, buyers and quality assurance teams verifying consignment mass
- Customs and trade dispute resolution where standardized mass determination is required
Practical benefits include repeatable, defensible mass calculations, reduced trade disputes, and consistent application of commercial moisture regain or allowances.
Related standards
- ISO 6741-2 (sampling methods), ISO 6741-3 (specimen cleaning), ISO 6741-4 (commercial allowances & moisture regains)
- ISO 139 (standard atmospheres), ISO 1130 (sampling for testing), ISO 6343/6348 (terminology and mass determination), ISO 5089, ISO 3534, ISO 3074 (referenced test/sample standards)
For precise drying temperatures, formulae and numerical tables, consult the full ISO 6741-1:1989 document.