Overview
ISO 19396-2:2025 - "Paints and varnishes - Determination of pH value - Part 2: pH sensors with ISFET technology" specifies a standardized method to measure the pH of dispersions and coating materials using ISFET pH sensors. This second edition (2025) updates terminology and calibration guidance from the 2017 edition and defines apparatus, sampling, calibration, measurement procedure, evaluation and reporting requirements for reliable pH determination in paints and varnishes.
Key topics and requirements
- Scope and principle: Method tailored for polymer dispersions and coating materials measured potentiometrically with an ISFET sensor combined with a reference electrode. An integrated temperature sensor is recommended and temperature is always recorded.
- Apparatus: Requires a pH meter suitable for ISFETs, an ISFET sensor unit (ISFET + reference electrode), buffer solutions, containers, cleaning tools and optional stand/stirring/thermostat.
- pH meter functions (minimum):
- pH reading accuracy of 0.01 pH
- pH-proportional voltage readout with at least 1 mV accuracy
- Ability to set offset (zero point) and practical slope obtained during calibration
- Temperature indication and temperature compensation (manual or automatic)
- Sensor details: ISFET combines an ion-sensitive oxide film (gate) and reference electrode in one unit; the H+ activity at the oxide surface produces the pH-dependent voltage.
- Buffers and calibration: Use certified buffer solutions (with known uncertainty, stability and temperature dependence) for calibration and slope adjustment per manufacturer and clause 7.2.
- Sampling & preparation: Follow ISO 15528 (sampling) and ISO 1513 (sample prep) to ensure representative test material.
- Quality & precision: The document specifies repeatability and reproducibility assessment (interlaboratory precision reported in Annex A) and requires a complete test report with conditions, calibration and results.
Applications and who uses it
- Quality control laboratories in paint, coating and dispersion manufacturing for batch release and stability monitoring.
- R&D and formulation teams evaluating acidity, storage stability and compatibility.
- Instrument manufacturers and metrology labs verifying ISFET performance and calibration procedures.
- Compliance and testing laboratories performing standardized pH measurement for specifications and customer contracts.
Related standards
Keywords: ISO 19396-2:2025, pH measurement, ISFET sensor, paints and varnishes, coating materials, buffer solutions, temperature compensation, calibration, pH meter.
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