Overview
EN ISO 18314-2:2023 - Analytical colorimetry Part 2 - defines corrections, calculation methods and performance criteria for quantitative colour measurements used with pigments, paints and coatings. Published by CEN/ISO in 2023 (second edition), the standard specifies the Saunderson correction for different measurement geometries and gives solutions of the Kubelka–Munk equation for hiding and transparent layers. It also standardizes procedures for calculating tinting strength, depth of shade, residual colour difference, and hiding power. Sample preparation procedures are excluded and are agreed separately.
Key topics and requirements
- Saunderson correction: procedures to correct reflectance measurements for instrument geometry (including incidence diffuse / observation 0° (d:0°) and 45°:0° geometries).
- Kubelka–Munk solutions: two solution methods are provided for applying the Kubelka–Munk model to both hiding and transparent layers; methods are intended for consistent calculation of absorption and scattering (K/S) behaviour.
- Tinting strength criteria: standardized criteria for relative tinting strength including:
- K/S value at the absorption maximum
- Weighted sum of K/S values
- Tristimulus value Y
- The smallest tristimulus of X, Y, Z
- Shade depth parameter (depth of shade)
- Residual colour difference: methods to compute the remaining colour difference (e.g., ΔE*) between reference and test white reductions when tinting strength has been equalized.
- Hiding power: procedures and criteria (for example contrast ratio thresholds) to determine the ability of a pigmented medium to obliterate substrate colour.
- Metrological quality: repeatability and reproducibility requirements and annexed coefficient tables for standard illuminants and observers (e.g., D65/10° and C/2°).
Practical applications
- Quality control and specification of pigments, extenders and colourants for consistent performance in paints, inks and plastics.
- Formulation and R&D: comparing tinting strength of new pigments against references; predicting shade depth and hiding performance.
- Instrument calibration and interlaboratory testing for colour measurement and reporting.
- Supporting product datasheets and claims about coverage (hiding power), tinting efficiency and colour matching.
Who should use this standard
- Colour chemists, formulation scientists and R&D teams in coatings, inks and plastics industries
- Quality control laboratories and testing houses
- Pigment and extender manufacturers and suppliers
- Instrument manufacturers and calibration laboratories
- Standards bodies and conformity assessment bodies
Related standards
- ISO 18451 series (terminology and related analytical colourimetry parts)
- National or industry standards describing sample preparation (sample prep is excluded from EN ISO 18314-2:2023)
Keywords: Analytical colorimetry, Saunderson correction, Kubelka–Munk, tinting strength, hiding power, depth of shade, EN ISO 18314-2:2023, pigments, paints, colour measurement.
