Overview
ISO 787-24:1985 is an international standard developed by the International Organization for Standardization (ISO) that specifies general methods of test for pigments and extenders-specifically, the determination of relative tinting strength of coloured pigments and relative scattering power of white pigments using photometric methods. This standard serves as a critical reference for manufacturers, quality control laboratories, and researchers within the paints, coatings, and pigments industries, aiming for reliable and consistent evaluation of pigment performance.
The procedures described in ISO 787-24 provide an instrumental alternative to the visual-based methods detailed in ISO 787-16 and ISO 787-17, thus minimizing subjective influences in pigment evaluation.
Key Topics
- Photometric Evaluation: The standard emphasizes the use of objective, instrumental photometric methods for measuring reflectivity and, in turn, calculating tinting strength and scattering power.
- Relative Tinting Strength: Equal masses of a coloured pigment and a reference material are mixed with a white pigment paste. The reflectivity of each dispersion is measured, and results are used to determine the pigment's tinting strength relative to the standard reference.
- Relative Scattering Power: For white pigments, equal masses of a test and a reference pigment are each dispersed in a black pigment paste. Their reflectivity is measured at a wavelength of 550 nm to derive the relative scattering power.
- Kubelka-Munk Analysis: Results are processed using the Kubelka-Munk equations, allowing calculation of absorption and scattering coefficients from the photometric data.
- Test Reporting: The standard outlines key elements that must be included in test reports, ensuring transparency and reproducibility of results.
Applications
ISO 787-24:1985 is widely used in several practical scenarios:
- Quality Control: Manufacturers of paint, pigment, and extender products rely on these standardized methods to ensure batch-to-batch consistency and adherence to product specifications.
- Product Development: R&D teams use this method to compare new pigment formulations with established references for performance benchmarking.
- Regulatory Compliance: The objective photometric methods support compliance with both internal and external standards, helping manufacturers meet industry requirements.
- Procurement and Supply Chain: Buyers and suppliers of pigments can use these standardized tests for technical evaluations and comparisons in purchasing decisions.
Key industries benefiting from ISO 787-24:1985 include:
- Paints and coatings
- Plastics compounding
- Construction materials
- Printing inks
- Ceramics and enamels
Related Standards
ISO 787-24 is part of the broader ISO 787 series, which together form a comprehensive suite of general test methods for pigments and extenders. Related standards include:
- ISO 787-16: Determination of relative tinting strength of coloured pigments-Visual comparison method
- ISO 787-17: Comparison of lightening power of white pigments-Visual comparison method
- ISO 591: Titanium dioxide pigments for paints
- ISO 842: Raw materials for paints and varnishes-Sampling
- ISO 1524: Determination of fineness of grind
- ISO 3219: Plastics-Polymers in the liquid, emulsified or dispersed state-Determination of viscosity
- ISO 787 parts 1–23: Covering tests for properties such as colour comparison, density, resistance to light, pH value, and more.
Practical Value
By providing a detailed, reproducible protocol for photometric assessment of pigment properties, ISO 787-24:1985 enhances data quality and reliability in pigment testing worldwide. Its instrumental approach reduces subjectivity, improves inter-laboratory agreement, and supports the global harmonization of pigment quality standards. Adhering to ISO 787-24 not only ensures technical excellence but also builds trust between manufacturers, suppliers, and end users in the pigment and coating industries.
