Overview
SIST EN ISO 8781-3:1997 specifies a standardized method to assess the dispersion characteristics of pigments and extenders by evaluating changes in specular gloss. Published by the Slovenian Institute for Standardization (SIST), this standard adopts the ISO 8781-3:1990 framework and is widely applicable in the paints, coatings, and printing industries. The method involves dispersing pigments in stages within an agreed binder system, preparing test films, and measuring their gloss after each stage. Gloss measurements provide a reliable basis for comparing a test pigment with a reference pigment, aiding in quality control and product development.
Key terms include: pigment dispersion, gloss measurement, specular gloss, binder system, and dispersion characteristics.
Key Topics
- Assessment Purpose: Designed for comparing pigments or extenders with agreed reference standards to determine dispersion efficiency and product consistency.
- Dispersion Process: The pigment or extender is incorporated into a binder system and mechanically dispersed using recognized methods, as referenced in ISO 8780 series.
- Film Preparation: After each dispersion stage, a portion of the mill base is applied to a defined substrate and dried or stoved under controlled conditions.
- Gloss Measurement: Specular gloss is measured following the procedures described in ISO 2813. Measurements are taken at agreed angles and reported as mean gloss values.
- Graphical Evaluation: Gloss results are plotted against the level of dispersion (e.g., time, number of equipment revolutions). This provides a visual and quantitative representation of dispersion work required to reach a target gloss value.
- Reporting Requirements: The standard mandates documentation of test conditions, product identification, dispersion method, binder specifics, substrate details, gloss data, and any deviations.
Applications
- Paints and Coatings: Ensuring consistent gloss development and pigment dispersion in decorative and industrial formulations.
- Printing Inks: Comparing dispersion efficiency to achieve optimal gloss levels and print quality.
- Quality Control: Routine testing for raw material acceptance and batch-to-batch consistency in pigment and extender materials.
- Product Development: R&D teams use the standard to benchmark new pigments or extenders against established references, facilitating improved formulations.
- Supplier Evaluation: Objective assessment when evaluating or qualifying alternative pigment or extender sources.
Related Standards
- ISO 2813: Paints and varnishes - Determination of specular gloss of non-metallic paint films at 20°, 60°, and 85°.
- ISO 8781-1: Assessment from the change in tinting strength of colored pigments.
- ISO 8781-2: Assessment from the change in fineness of grind.
- ISO 8780 (Parts 1-6): Series detailing standardized dispersion methods (e.g., oscillatory shaking, high-speed impeller mill, bead mill, triple-roll mill, automatic muller).
- ICS 87.060.10: Pigments and extenders classification.
Adopting SIST EN ISO 8781-3:1997 ensures reliable, repeatable, and internationally recognized assessment of pigment dispersion via gloss change, supporting product quality and regulatory compliance in pigment-related industries.
