Overview
ISO 6741-3:1987 - "Textiles - Fibres and yarns - Determination of commercial mass of consignments - Part 3: Specimen cleaning procedures" defines the cleaning methods to be used on laboratory test specimens prior to determination of clean, dry commercial mass. It is part of the ISO 6741 series and is intended for use by independent third parties performing invoice-mass checks or commercial mass determinations in trade, inspection and laboratory environments.
Key topics and technical requirements
- Scope and relationship: Applies when commercial mass must be reported on a clean, dry basis. Specimens are prepared per ISO 6741-1 and ISO 6741-2; the appropriate cleaning route is selected following ISO 6741-4.
- Destructive nature: Most cleaning procedures are destructive - laboratories must use appropriate apparatus and chemically pure reagents.
- Bag and thimble specifications: Specimens are enclosed in open-textured bags (polyamide or polyester for many methods; unsized cotton for solvent extraction) with oven-dry mass determined to ±0.05 % accuracy.
- Defined cleaning methods:
- Method A1: Washing with soap (70–75 °C, agitation, multiple rinses, enzyme desizing if required).
- Method A2: Alkaline boiling with sodium carbonate (boiling treatments and repeated rinses).
- Method B: Washing with IEC test detergent (per annex) instead of soap.
- Method C: Soxhlet extraction with light petroleum (40–60 °C boiling range).
- Method D: Soxhlet extraction with dichloromethane (methylene chloride).
- Method E: Soxhlet extraction with methanol.
- Method F: Washing in soft or distilled water with extended agitation and rinses.
- Method G: Cleaning by pyrolysis (ashing in a muffle furnace at 625 ± 20 °C) for certain residue removals.
- Method Z: Other agreed procedures where standard methods are unsuitable.
- Apparatus details: Soxhlet extraction, sintered-disc thimbles (porosity grade P40), centrifuging or squeezing, muffle furnace, desiccator, balance handling precautions.
- Safety and handling: Warnings about toxic fumes (e.g., hydrogen cyanide from acrylic ashing) and volatile metal emissions; avoid fumes entering the laboratory; never touch specimens with bare hands.
Applications and users
- Primary users: Textile testing laboratories, independent inspection agencies, customs and trade inspectors, quality control teams in fibre and yarn manufacturing, and parties to commercial textile contracts.
- Practical uses:
- Establishing or verifying invoice mass of consignments on a clean, dry basis.
- Resolving buyer–seller disputes over declared mass.
- Routine QC to remove size, oils, finishes or contaminants before mass measurement.
- Preparing specimens for further analysis (e.g., fibre content tests).
Related standards
Keywords: ISO 6741-3:1987, specimen cleaning procedures, textile testing, commercial mass determination, Soxhlet extraction, detergent washing, pyrolysis, fibres and yarns.
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