Overview
ISO 3071:2020 - Textiles - Determination of pH of aqueous extract specifies a standardized laboratory method to measure the pH of an aqueous extract from textiles. The method is applicable to textiles in any form (fibres, yarns, fabrics) and is intended for routine quality control and conformity testing. The procedure measures pH electrometrically using a glass electrode after extracting soluble components into a potassium chloride solution.
Key Topics and Requirements
- Scope: pH measurement of aqueous extracts from textiles (all forms).
- Extraction medium: 0.1 mol/L potassium chloride (KCl) solution (used instead of plain water in this edition).
- Specimen preparation:
- Cut representative laboratory sample into ~5 mm pieces.
- Take two test specimens of (2.00 ± 0.05) g each.
- Extraction procedure:
- Place each specimen in a stoppered flask with 100 mL of 0.1 mol/L KCl.
- Mechanically agitate (recommended 60 strokes/min or 30 rpm) for 2 h ± 5 min at ambient temperature.
- pH measurement:
- Use a calibrated pH-meter with a glass electrode (resolution at least 0.01 pH unit).
- Calibrate at the extract temperature using buffer solutions (recommended near pH 4, 7 and 9).
- Immerse electrode to at least 10 mm depth; perform measurements without rinsing between extracts as specified.
- Quality checks and calculations:
- If the two measured pH values differ by more than 0.2 (to 0.1 pH unit precision), repeat using new specimens.
- Report the average pH to 0.1 pH unit.
- Reporting requirements: must include reference to ISO 3071:2020, mean pH, pH and temperature of extraction solution, influencing factors (e.g., wetting issues), and test date.
- Performance: interlaboratory reproducibility reported (R ≈ 1.1 pH units using KCl extraction).
Applications and Users
ISO 3071:2020 is used by:
- Textile manufacturers and converters for in-process quality control.
- Independent textile testing laboratories and certification bodies.
- Regulatory agencies assessing consumer safety (skin compatibility, acidity/alkalinity limits).
- R&D and textile chemistry laboratories tracking processing residues and treatment history.
Practical uses include verifying neutralization after finishing, checking residual alkaline or acidic treatment agents, and ensuring compliance with buyer or regulatory pH limits.
Related Standards
- ISO 3696 - Water for analytical laboratory use (quality of water required).
- ISO 5725-2 - Accuracy (trueness and precision) of measurement methods (used for interlaboratory analysis).
Keywords: ISO 3071, textiles pH, pH of aqueous extract, textile testing, pH measurement, KCl extraction, pH-meter, quality control.