Overview
ISO 19396-1:2025 - Paints and varnishes - Determination of pH value - Part 1: pH sensors with glass membrane specifies a laboratory method for measuring the pH of polymer dispersions and coating materials using pH sensors with a glass membrane. The second edition updates terminology (replacing “pH electrode” with pH sensor), clarifies calibration, and aligns normative references. The standard covers equipment, sampling, calibration, measurement procedure, evaluation, precision, and test reporting.
Key topics and requirements
- Scope and purpose: Laboratory determination of pH for aqueous coatings and polymer dispersions using glass‑membrane pH sensors.
- Apparatus and materials: Requirements for the pH measuring apparatus include a pH meter, a pH sensor with glass membrane (combining measuring and reference half‑cells), buffer solutions, storage solution (e.g., KCl), cleaning agents and appropriate containers/stands.
- pH meter functions: The meter must display pH to 0.01 resolution, provide pH‑proportional voltage (accuracy at least 1 mV), allow offset/zero adjustment, adjust practical slope, and indicate measuring temperature. Temperature compensation (manual or automatic) is required; temperature must be recorded with pH.
- Sensor components: Glass membrane measuring electrode, reference electrode (commonly Ag/AgCl with KCl reference electrolyte), diaphragm types and chemical‑resistant shafts are described. Low‑maintenance sensors with gel/solid electrolytes are noted.
- Calibration and measurement: Calibration procedures using buffer solutions are specified; the practical slope and zero point are used to characterise sensor performance. Sampling, cleaning, and measurement conditions are defined to ensure reproducibility.
- Quality and reporting: Methods for evaluation, precision (repeatability and reproducibility) and required test report information are included. Informative annexes provide recommended sensors (based on interlaboratory tests) and precision determination.
Applications and users
ISO 19396-1:2025 is intended for:
- Quality control and R&D laboratories in paint, varnish, coatings and polymer dispersion manufacturing
- Test houses and certification bodies performing routine pH analysis
- Process engineers monitoring formulation stability, shelf life and product performance
- Suppliers of pH meters and sensors seeking compliance guidance
Practical benefits include consistent pH measurement procedures, improved interlaboratory comparability, and guidance on sensor selection and calibration for coating materials.
Related standards
Keywords: ISO 19396-1:2025, pH measurement, paints and varnishes, pH sensors with glass membrane, polymer dispersions, coating materials, pH calibration, pH meter.
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