1 Scope
This part of EN 13523 specifies procedures for determining the instrumental colour difference (CIELAB) of an organic coating on a metallic substrate.
Establishing a standard as well as the magnitude of an acceptable colour difference are not covered by this method.
Two methods are given in this part of EN 13523:
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a) instrumental colour difference measurement using a tristimulus colorimeter;
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b) instrumental colour difference measurement using a spectrophotometer or equivalent.
Care should be taken when measuring e.g.
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— textured surfaces;
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— fluorescent coatings;
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— metameric coatings;
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— multi-coloured, pearlescent, metallic or special colour effect coatings.
In order to determine whether metamerism is present, the metamerism index is determined (see EN 13523‑15) and/or a visual examination (see EN 13523‑22) is performed with different artificial light sources.