Overview
ISO 787-5:1980 specifies a general test method for determining the oil absorption value of pigments and extenders. This standardized test measures the quantity of refined linseed oil absorbed by a sample under defined conditions, reflecting the oil absorption characteristics crucial for formulations in paints, coatings, and related industries. Accurate assessment of oil absorption value is essential for quality control and product specification, ensuring consistency in pigment and extender performance.
Key Topics
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Scope
The standard describes a reproducible procedure to measure the oil absorption value by gradually adding linseed oil to a test portion of pigment or extender until a uniform paste of smooth consistency is achieved.
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Test Principle
Linseed oil is added incrementally from a burette to the sample on a plate. After each addition, the oil is rubbed into the material with a palette knife until conglomerates appear. The process continues dropwise until the paste just spreads without cracking or crumbling.
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Quantitative Expression
Results are expressed either as millilitres of oil per 100 g of product or as grams of oil per 100 g, providing flexibility in documentation.
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Apparatus and Reagents
The test requires:
- A ground glass or marble plate (approx. 300 × 400 mm)
- A palette knife with precise blade dimensions for effective mixing
- A 10 ml burette conforming to ISO requirements
- Refined linseed oil compliant with ISO 150 standards
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Sampling and Test Portions
Proper representative sampling as per ISO 842 is essential. Test portion mass varies based on expected oil absorption value, ranging from 1 g to 20 g for different pigment/extender types.
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Procedure Details
The operator works the oil thoroughly with the pigment, keeping the total mixing time between 20 to 25 minutes to standardize effort and ensure consistent results.
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Test Reporting
Reports must include product identification, reference to ISO 787-5, test results, any procedural deviations, and test date. Comparisons with agreed product samples are recommended for quality assurance purposes.
Applications
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Paints and Coatings Industry
Determining oil absorption informs paint formulation, affecting viscosity, drying time, and final coating properties. It helps optimize pigment-to-binder ratios for improved flow and coverage.
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Pigment and Extender Manufacturing
Routine quality control to classify materials, ensuring batch-to-batch consistency and adherence to product specifications.
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Research and Development
Enables comparison of new pigment preparations and extenders, supporting innovations in paint technology and material performance.
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Standardization and Compliance
Facilitates harmonized testing across laboratories and manufacturers worldwide, reducing variability in product evaluations and supporting international trade.
Related Standards
ISO 787-5 is part of a comprehensive series of test methods for pigments and extenders under ISO 787, which includes:
- ISO 787-1: Comparison of colour
- ISO 787-2: Determination of matter volatile at 105°C
- ISO 787-4: Determination of acidity or alkalinity of aqueous extract
- ISO 787-6: Determination of residue on sieve - Oil method
- ISO 787-10: Determination of density - Pyknometer method
These interconnected standards establish a full profile of physical and chemical characteristics of pigments and extenders, supporting robust product evaluation.
Keywords: ISO 787-5, oil absorption value, pigment testing, extender testing, linseed oil absorption, paint formulation, quality control, pigment standards, ISO test methods, refined linseed oil, paint additives, pigment properties.
Open preview (PDF)General methods of test for pigments and extenders — Part 5: Determination of oil absorption value