NBN EN 13523-3:2024

NBN EN 13523-3:2024

Coil coated metals - Test methods - Part 3: Colour difference and metamerism - Instrumental comparison

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This document specifies procedures for determining the instrumental colour difference (CIELAB or ) of an organic coating on a metallic substrate compared to another one used as a reference (usually called reference) and the metamerism depending on the illuminant. When two colour specimens have identical spectral reflectance curves, they are matching under any illuminant irrespective of its spectral characteristics. This is termed a “spectral match”. It is also possible for two colour specimens having different spectral reflectance curves to match visually under a given light source but not to match under another light source with different spectral characteristics such matches are termed metameric". One quantitative description of metamerism is the so-called "metamerism index". Information on the metamerism index is of limited value where ?E (instrumental colour difference for a given illuminant) is > 0,5. The metamerism index is not suited for determining the absolute colour difference or colour consistency of a given specimen at change of illuminant. The colour difference under the reference illuminant is to be measured in colour coordinates L*, a* and b*. Excluded from this method are organic coatings producing fluorescence and/or which are multicoloured, pearlescent or metallic. Establishing a reference as well as the magnitude of an acceptable colour difference are not covered by this method. Two methods are given in this document: a) instrumental colour difference measurement using a tristimulus colourimeter b) instrumental colour difference measurement using a spectrophotometer or equivalent. It is advised that care is taken when measuring e.g. - textured surfaces - fluorescent coatings - metameric coatings - multi-coloured, pearlescent, metallic or special colour effect coatings. "
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Información adicional

Autor Bureau de Normalisation Belge (NBN)
Publicado por NBN
Tipo de Documento Norma
ICS 25.220.60 : Recubrimientos orgánicos
Reemplaza NBN EN 13523-3:2021
histórico No
Palabra clave EN 13523-3, EN 13523-3:2024