EN ISO 3668:2020 PDF

Overview

EN ISO 3668:2020 (ISO 3668:2017) - "Paints and varnishes - Visual comparison of colour of paints" specifies a standardized method for visually comparing the colour of paint films against a standard using controlled artificial illumination in a colour‑matching booth. The standard is intended for routine colour matching and referee assessments and excludes coatings containing special‑effect pigments (e.g., metallic) unless all illuminating and viewing conditions are agreed in advance.

Key topics and requirements

• Scope and principle: Visual comparison of paint films under specified illumination and viewing conditions; includes assessment of hue, chroma and lightness components and metamerism.
• Colour‑matching booth: Use an enclosed booth that excludes external light and provides artificial light sources approximating CIE illuminant D65, CIE illuminant A, or CIE illuminant FL 11. Light sources outside these distributions require agreement between parties.
• Illumination level: Recommended illuminance at the viewing position is 1 000 lx to 4 000 lx (higher values desirable for dark colours).
• Surroundings: Interior should be matt neutral grey (L* ≈ 45–55; a* and b*