ISO 1833-11:2017

Overview

ISO 1833-11:2017 - Textiles: Quantitative chemical analysis - Part 11 - specifies a standardized sulfuric acid method to determine the mass percentage of cellulose fibres (after removal of non‑fibrous matter) in textile mixtures. The method applies to mixtures of natural and man‑made cellulose fibres (e.g., cotton, flax, hemp, ramie, viscose, cupro, modal, lyocell) blended with synthetic fibres such as polyester, polypropylene, elastomultiester, elastolefin and polypropylene/polyamide bicomponent fibres.

Key Topics and Requirements

• Principle: Cellulose fibres are dissolved from a known dry mass of fabric using 75% (mass fraction) sulfuric acid; the undissolved residue is collected, washed, dried and weighed. The cellulose proportion is calculated by difference.
• Reagents: 75% sulfuric acid (acceptable range 73–77%) and dilute ammonia solution for washing.
• Procedure essentials:
  • Use 200 ml sulfuric acid per gram of specimen.
  • Maintain reaction at (50 ± 5) °C for 1 hour with intermittent gentle shaking.
  • Filter residue through a weighed crucible, perform controlled washings (cold water and dilute ammonia), dry and weigh.
  • Do not apply suction until washings have drained by gravity.
• Apparatus: Conical flask (min. 500 ml, glass‑stoppered), heating apparatus to hold the set temperature, filter crucible and standard laboratory equipment as specified in ISO 1833‑1.
• Calculation: Follow general instructions in ISO 1833‑1; use d = 1.00 except for propylene/polyamide bicomponent where d = 1.01.
• Precision: Confidence limits on homogeneous mixtures are ≤ ±1 percentage point at 95% confidence.

Applications and Who Uses It

• Quality control and acceptance testing in textile manufacturing and finishing to verify fibre composition claims.
• Independent textile testing laboratories performing quantitative chemical analysis for labelling, compliance, and dispute resolution.
• Product development and research where accurate fibre composition of blends (cellulose + synthetic) is required.
• Regulatory and certification bodies assessing conformity with product standards and labelling legislation.
• Practical uses include blended apparel, technical textiles, home textiles and materials containing bicomponent fibres.

Related Standards

• ISO 1833-1 - Textiles - Quantitative chemical analysis - Part 1: General principles of testing (normative reference and procedural framework).
• ISO 1833 series - other parts cover different fibre mixtures and methods; refer to the ISO catalogue for the complete series.

Keywords: ISO 1833-11:2017, sulfuric acid method, textile quantitative chemical analysis, cellulose fibres, cotton, viscose, polyester, polypropylene, bicomponent fibres, textile testing, fibre composition, quality control.