Overview
ISO 787-2:2021 defines a general, gravimetric test method for determining the mass fraction (percentage) of matter volatile at 105 °C in pigments and extenders. This method applies to materials that are stable at 105 °C and is intended to support reproducible quality control, process monitoring and consistent test reporting across laboratories and production facilities.
Key Topics
- Scope and applicability: The procedure is for pigments and extenders that remain stable at 105 °C; it quantifies volatile content as a mass fraction in percent.
- Apparatus: Required equipment includes a low-form weighing dish with a ground-glass lid, an oven capable of (105 ± 2) °C, a balance accurate to 0.1 mg, and a desiccator with a suitable drying agent.
- Sampling: Representative sampling shall follow ISO 15528 to ensure that the test portion reflects the product lot.
- Procedure essentials:
- Preheat and weigh the empty dish, cool in a desiccator and record mass.
- Place an approximately (10 ± 1) g test portion in the dish (adjust mass if apparent volume is high), heat at (105 ± 2) °C, cool and weigh.
- Reheat the dish and residue for at least 1 h, then in subsequent 30 min cycles until two consecutive mass results differ by no more than 5 mg; record the lowest mass.
- Perform the determination in duplicate and calculate the mean when duplicate results differ by no more than 10% of the higher value.
- Calculation: The volatile-matter content (ω, %) is calculated from the mass of the dish and sample before and after heating using the formula provided in the standard.
- Reporting: Test reports must reference ISO 787-2:2021 and include product identification, results (to 0.1 %), any deviations from the procedure (e.g., altered sample mass or test temperature), observed anomalies and test date.
Applications
- Quality control: Routine assessment of pigments and extenders to detect undesirable volatile content that can affect processing, paint formulation and final product performance.
- Incoming inspection: Verification of supplier claims and batch conformity before use in production.
- Process control: Monitoring drying and handling processes where residual volatiles are critical for downstream operations.
- Regulatory and conformity checks: Providing documented, repeatable results for compliance and traceability.
Related Standards
- ISO 15528 - Sampling of paints, varnishes and raw materials (referenced for representative sampling).
- ISO 18451-1 - Terminology for pigments, colorants and extenders (defines terms used).
For practical implementation, ensure laboratory equipment is calibrated, follow ISO 15528 sampling practices, and document any deviations in the test report to preserve traceability and interpretability of volatile-matter results.
Open preview (PDF)General methods of test for pigments and extenders — Part 2: Determination of matter volatile at 105 °C
