ISO 20705:2019

Overview

ISO 20705:2019 - Textiles - Quantitative microscopical analysis - General principles of testing - specifies standard procedures for determining the composition of textile samples that contain mixtures of fibres which cannot be separated mechanically or chemically. The standard defines microscopical methods using a light microscope (LM) or a scanning electron microscope (SEM) and sets out how to measure either the apparent fibre diameter (longitudinal view) or the fibre section area (cross view) depending on fibre section shape. It provides calculation principles to convert fibre counts and measurements into percentage by mass using conventional fibre densities (Annex A) and includes statistical guidance (Annex B).

Key topics and technical requirements

• Scope and principle: Quantitative microscopical analysis for fibres in any textile form when chemical separation (ISO 1833 series) is not practicable. Identification, counting and measurement of fibre types form the basis of composition by mass.
• Microscopy methods:
  • LM: transmitted-light microscope (or projection LM) capable of ×150 to ×500 magnification with a movable stage and eyepiece graticule.
  • SEM: imaging for longitudinal or cross views; magnification calibration referenced (ISO 16700).
• View selection:
  • Use longitudinal views and apparent diameter measurements for near-circular fibre sections.
  • Use cross views and section area measurements for non-circular sections.
• Specimen preparation: Procedures for loose fibres, slivers, yarns (including disentangling plied yarns), woven and knitted fabrics; slide and stub preparation, microtomy for cross sections.
• Reagents and apparatus: neutral liquid medium (e.g., liquid paraffin), resin (2‑hydroxyethyl methacrylate), slides, cover glasses, microtome, SEM stubs.
• Calculations and reporting: Counting, measurement, inclusion of conventional densities (Annex A), statistical data for measurement uncertainty (Annex B), and required elements of the test report.
• Normative references: ISO 1833-1 (general chemical analysis principles); ISO/TR 11827 referenced for fibre section shapes.

Practical applications and users

Who uses ISO 20705:2019:

• Textile testing laboratories and fibre analysts performing composition analysis when mechanical or chemical separation is impractical.
• Quality control teams confirming fibre content of yarns, woven or knitted fabrics, slivers and loose fibres.
• Forensic laboratories, research institutions, and certification bodies requiring standardized microscopical quantification. Practical use cases:
• Determining mass percentage of blends (examples: cashmere/wool, cotton/flax, flax/hemp).
• Validating product labels and resolving disputes about fibre composition.
• Research on fibre morphology and blend performance where accurate quantitative microscopical data are required.

Related standards

• ISO 1833 series - Quantitative chemical analysis of textiles (preferred when chemical separation is feasible).
• ISO/TR 11827 - Visual references for fibre section shapes.
• ISO 16700 - SEM magnification calibration guidance.

Keywords: ISO 20705:2019, quantitative microscopical analysis, textile fibre analysis, light microscope, scanning electron microscope, fibre diameter, fibre section area, mass percentage, fibre mixtures.