ISO 787-25:2019 PDF

General methods of test for pigments and extenders — Part 25: Comparison of the colour, in full-shade systems, of white, black and coloured pigments — Colorimetric method

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Title (English):

ISO 787-25:2019

General methods of test for pigments and extenders — Part 25: Comparison of the colour, in full-shade systems, of white, black and coloured pigments — Colorimetric method

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 9
Publication date:: February 7, 2019
Edition:: ISO IS 787 edition 2 version 1
ICS:: 87.060.10

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Description (English):

This document specifies a general test method for comparing the colour, in full-shade systems, of white, black or coloured pigments with that of an agreed reference pigment, using a colorimetric procedure.

Technical details

Technical committee: ISO/TC 256 - Pigments, dyestuffs and extenders
SKU: ISO 787-25:2019

Abstract

Overview

ISO 787-25:2019 specifies a colorimetric test method for comparing the colour, in full‑shade (optically hiding) systems, of white, black and coloured pigments against an agreed reference pigment. The standard describes preparation of a defined test medium, dispersion and specimen preparation, colour measurement using spectrometers or tristimulus colorimeters, and expression of results (e.g., relative hue, lightness, chroma and total colour difference).

Keywords: ISO 787-25, pigments, extenders, colour comparison, colorimetric method, full-shade systems, pigment testing, spectrometer, tristimulus colorimeter.

Key topics and technical requirements

Scope and principle
- Compares the colour of a test pigment and an agreed reference in a single‑pigment (mass tone/full shade) system using tristimulus measurements and colourimetry (ISO 18314-1; ISO 11664-4 for derived attributes).
Test medium
- Preferred binder: an alkyd resin composed of 63% linseed oil, 23% phthalic anhydride, 14% trimethylol propane with specified acid value, viscosity and hydroxyl value.
- Fumed silica (to prevent flocculation and control flow) blended at a recommended ratio; preferred mix: 97 parts alkyd : 3 parts fumed silica, dispersed on a triple‑roll mill.
- Fumed silica requirements include BET surface area 175–225 m2/g and pH of a 4% aqueous dispersion 3.6–4.5.
Sample preparation and apparatus
- Use of an automatic muller (ground‑glass plates), triple‑roll mill for pre‑dispersion, film applicator, suitable non‑fluorescent substrates and stencils/glass covers.
Measurement and instrument requirements
- Spectrometer or tristimulus colorimeter per ISO 18314‑1.
- Special provisions for black pigments: high instrument accuracy, zero adjustment using a light‑trap black standard and repeatability requirement where standard deviation σ of consecutive tristimulus measurements must be **

Related standards

Standards mentioned in the description

ISO 787-25:2019 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Related standards

Abstract

Overview

Key topics and technical requirements

Related standards

General methods of test for pigments and extenders - Comparison of the colour, in full-shade systems, of whit…

Analytical colorimetry - Part 1: Practical colour measurement (ISO 18314-1:2015)

Colorimetry - CIE 1976 Lab* Colour space

ISO 787-25:2019 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Related standards

Abstract

Overview

Key topics and technical requirements

Related standards

General methods of test for pigments and extenders - Comparison of the colour, in full-shade systems, of whit…

Analytical colorimetry - Part 1: Practical colour measurement (ISO 18314-1:2015)

Colorimetry - CIE 1976 L*a*b* Colour space

Colorimetry - CIE 1976 Lab* Colour space