Overview
EN ISO 787-17:2019, titled General methods of test for pigments and extenders - Part 17: Comparison of lightening power of white pigments, is a European and international standard developed and maintained by CEN and ISO technical committees. This standard specifies a rigorous method for comparing the lightening (also called reducing) power of white pigments with a reference pigment sample of the same type. The document is essential for ensuring consistent pigment quality and performance in various industrial applications involving pigments and extenders.
The standard provides two validated test procedures:
- Procedure A: A quicker method ideal for testing a single pigment sample.
- Procedure B: A more thorough approach suited for multiple samples or pigments with unknown lightening power.
By following these standardized methods, manufacturers and quality control laboratories can reliably assess pigment properties, contributing to product consistency and compliance with industry expectations.
Key Topics
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Scope and Purpose
The standard defines procedures for determining the relative lightening power of white pigments. It facilitates comparison with an agreed reference pigment, making it crucial in pigment quality assurance and material specification.
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Test Reagents and Materials
The test uses a specifically formulated blue paste consisting of castor oil, precipitated calcium sulfate, ultramarine blue pigment, and treated natural earth. This medium provides a controlled environment for pigment incorporation and testing.
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Apparatus Requirements
Essential apparatus include:
- Palette knife for mixing
- Glass slide for sample spreading
- Automatic or hand mullers for pigment incorporation
- Analytical balance accurate to ±0.001 g
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Sampling and Test Procedures
Samples are taken following ISO 15528 sampling methods to ensure representativeness.
- Procedure A involves mixing the test pigment with a blue paste using an automatic or hand muller and visually comparing the colour intensity against a reference pigment.
- Procedure B is designed for multiple tests or comparative studies, using similar mixing but allowing more detailed analysis.
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Expression of Results and Reporting
The results express the lightening power ratio relative to the reference pigment. The standard emphasizes documenting testing conditions, quantities, and outcomes in a test report for traceability and comparison.
Applications
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Quality Control for Pigment Manufacturers
Enables consistent evaluation of white pigment batches, ensuring products meet expected lightening power specifications.
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Paints and Coatings Industry
Critical for formulating white pigments that impart desired brightness and opacity in paints, varnishes, and coatings.
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Plastics and Paper Industries
Helps in selecting appropriate extenders and pigment grades to achieve optimal whitening and opacity effects.
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Research and Development
Assists in developing new pigment types and enhancing existing ones through standardized performance comparisons.
Related Standards
- ISO 788 - Ultramarine pigments for paints: Defines specifications and testing of ultramarine blue pigment used in the preparation of blue paste for this test.
- ISO 15528 - Sampling for paints, varnishes and raw materials: Guides representative sampling methodology, referenced for sample collection.
- ISO 18451-1 - Terminology for pigments, dyestuffs, and extenders: Provides the standardized terms and definitions used within EN ISO 787-17:2019.
By adhering to EN ISO 787-17:2019, stakeholders can guarantee a reliable, reproducible assessment of white pigment lightening power, facilitating product standardization and enhancing the performance consistency of end-use materials. This standard is a vital reference for laboratories, manufacturers, and quality assurance professionals working with pigments and extenders worldwide.
