Overview
EN ISO 1833-20:2019 (ISO 1833-20:2018) is a standardized test method for determining the mass percentage of elastane in textile mixtures using dimethylacetamide (DMA). The method measures elastane content after removal of non-fibrous matter in fabrics that combine certain elastane fibres with cotton, viscose, cupro, modal, lyocell, polyamide, polyester or wool. The procedure is not applicable if acrylic fibres are present. This standard is part of the ISO 1833 series for quantitative chemical analysis of textiles.
Key topics and technical requirements
- Principle: Elastane is dissolved out of a known dry mass of the specimen using DMA; the remaining residue is washed, dried and weighed. Elastane percentage is calculated by difference.
- Reagent: Dimethylacetamide (DMA) - note safety precautions because DMA can be harmful.
- Apparatus:
- Conical glass flask (min. 250 ml) with stopper
- Heating apparatus to maintain 60–65 °C
- Filter crucible (weighted) and suction setup
- Test procedure highlights:
- Add 150 ml DMA per gram of specimen
- Pre-wet, heat in a double boiler at 60 °C for at least 30 minutes with intermittent shaking
- Filter, wash residue with water, dry, cool and weigh
- Avoid suction during initial gravity drainage
- Calculation: Follow ISO 1833-1 general instructions; use correction factor d = 1.00 (except wool 1.01, cotton 1.02).
- Precision: Confidence limits on homogeneous mixtures are ±1 percentage point (95% confidence).
- Limitations: Not to be used for textiles containing acrylic fibres; other ISO 1833 parts (e.g., ISO 1833-12, ISO 1833-21) may apply to some mixtures.
Applications and users
This method is widely used for:
- Quality control and composition verification in textile production and finishing
- Lab testing by accredited textile testing laboratories and third-party compliance bodies
- Product labelling and regulatory compliance, ensuring accurate fibre-content declarations
- R&D and blend development to quantify elastane proportion in stretch fabrics
- Inspection and due diligence for sourcing, import/export checks, and consumer protection
Typical users include textile manufacturers, quality managers, testing laboratories, certification bodies, and technical auditors.
Related standards
- ISO 1833-1 - General principles for quantitative chemical analysis of textiles
- ISO 1833-12 and ISO 1833-21 - Alternative methods for some elastane-containing mixtures
- ISO 2076, ISO 6938 - Related nomenclature and definitions for fibre types
Keywords: EN ISO 1833-20:2019, ISO 1833-20:2018, elastane content, dimethylacetamide (DMA), textiles quantitative chemical analysis, textile composition testing, fibre-content analysis.
