Overview
ISO 3074:2014 specifies a laboratory method for determining the dichloromethane‑soluble matter in combed wool sliver (and can be extended to wool in other forms). The procedure uses Soxhlet extraction with dichloromethane (methylene chloride) to quantify solvent‑extractable oils and fats (wool grease, processing oils, detergents and finishing agents). The method is intended for 100% wool products and can give misleading results on blends or non‑wool fibres.
Key topics and requirements
- Scope and limitation: Applicable principally to combed sliver and other wool forms; not suitable for mixed‑fibre products. Extraction with dichloromethane does not remove all fatty material - stronger swelling solvents extract additional residues.
- Principle: Soxhlet extraction with dichloromethane; evaporate solvent, oven‑dry residue and extracted specimen, express extractable matter as a percentage of oven‑dry specimen mass.
- Reagents & safety:
- Dichloromethane (boiling range 39–41 °C), residue ≤ 1 mg per 100 ml; toxic - use adequate ventilation.
- Acetone (analytical reagent quality) recommended for drying aid.
- Apparatus & conditions:
- Soxhlet extractor (200–300 ml barrel; 250 ml flask), distillation unit, water bath (~45 °C if used), oven at 105 °C ± 3 °C, analytical balance (0.0001 g) and balance (0.01 g).
- Test specimens: two duplicates of about 10 g ± 0.5 g each.
- Extraction: adjust heating for at least 6 siphon cycles per hour, allow 20–24 siphonings.
- Drying: 120 minutes at 105 °C ± 3 °C, then desiccate, cool and weigh.
- Calculation & reporting:
- Percentage of dichloromethane‑soluble extract = (oven‑dry mass of residue / oven‑dry mass of extracted specimen) × 100.
- Report individual results, mean to nearest 0.1%, reference ISO 3074 and Soxhlet volume.
Applications and users
ISO 3074:2014 is used for:
- Quality control in wool processing, scouring and finishing operations.
- Determining solvent‑extractable oil/fat content to estimate clean wool content.
- Inter‑laboratory testing and product specification compliance for 100% wool textiles.
Key users:
- Textile testing laboratories and QC teams
- Wool processors, combers and scouring plants
- Research institutions studying wool chemistry or finishing agents
- Certification bodies and standards organizations
Related standards
- ISO 139 - Standard atmospheres for conditioning and testing
- ISO 1130 - Sampling methods for textile fibres
- IWTO‑10‑03 - IWTO method on dichloromethane extractables
- FZ/T 20018‑2010 - Chinese standard on dichloromethane extraction in textiles
Keywords: ISO 3074:2014, dichloromethane‑soluble matter, combed sliver, wool testing, Soxhlet extraction, solvent extraction, textile testing, wool grease.
