Customers Who Bought This Also Bought
-
CEN PREN ISO 6509
Priced From $25.00 -
CEN PREN 419111-2
Priced From $25.00 -
CEN EN 14501/PRA1
Priced From $25.00 -
CEN PREN 16853
Priced From $25.00
About This Item
Full Description
This document specifies procedures for determining the instrumental colour difference (CIELAB ∆E*Lab or ∆E00) 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 ΔE (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*, α* 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.