Overview
EN ISO 787-9:2019 (ISO 787-9:2019) defines a general laboratory method for the determination of the pH value of an aqueous suspension of pigments and extenders. Adopted by CEN, this part of the ISO 787 series provides a standardized procedure to measure pH reliably for quality control, product specification and formulation tasks in pigments, fillers and related raw materials.
Key topics and technical requirements
- Scope: pH measurement of an aqueous suspension of a pigment or extender sample.
- Sampling: Take a representative sample in accordance with ISO 15528.
- Reagents
- Use distilled or demineralized water with pH 5.0–8.0; protect water from atmospheric CO2.
- Optional buffer: 0.1% KCl solution prepared with the specified water.
- Suspension preparation
- Prepare a 5–10% (mass fraction) suspension in a chemically resistant glass container fitted with an unused ground-glass or rubber stopper.
- Stopper and shake, roll or stir vigorously; allow to stand for 5 minutes before measuring.
- If needed, use a neutral wetting agent (ethanol or methanol), up to 5 ml; reduce water volume to maintain original suspension concentration and check the wetting agent neutrality with a blank.
- Apparatus
- pH measuring device accurate to 0.1 pH unit, calibrated at test temperature.
- Balance with appropriate accuracy; chemically resistant glass container.
- Measurement and reporting
- Measure at room temperature; report pH to nearest 0.1 unit and suspension temperature to nearest 1 °C.
- Single determination (duplicate testing is no longer required in this edition).
- Test report must include product identification, reference to ISO 787-9, wetting agent details (if used), result and temperature, any deviations, and date.
Applications and users
This standard is practical for:
- Quality control and R&D laboratories in paints, coatings and pigment manufacturing
- Raw material suppliers and distributors verifying batch properties
- Formulators assessing compatibility and performance (e.g., dispersibility, stability)
- Third‑party testing and certification bodies requiring reproducible pH data
Accurate pH measurement helps with product specification, batch release, storage and formulation stability assessments.
Related standards
- ISO 15528 - Sampling of paints, varnishes and raw materials
- ISO 18451-1 - Terminology for pigments, dyestuffs and extenders
- Other parts of the ISO 787 series (general methods of test for pigments and extenders)
Keywords: EN ISO 787-9:2019, ISO 787-9, pH determination, pigments and extenders, aqueous suspension, pH measurement, paint raw materials, quality control.
