Overflatebehandling og -belegg

This document specifies a procedure for evaluating the resistance to continuous condensation of an organic coating on a metallic substrate, by means of exposure in a humidity cabinet under controlled conditions.

This document specifies procedures for determining the instrumental colour difference (CIELAB) 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*, 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. Care should be taken when measuring e.g. - textured surfaces; - fluorescent coatings; - metameric coatings; - multi-coloured, pearlescent, metallic or special colour effect coatings.

This Part of EN 13523 specifies a procedure for evaluating the humidity resistance of an organic coating (coil coating) on a metallic substrate, by means of exposure in a humidity cabinet under controlled conditions.

This part of EN 13523 specifies the procedure for determining the resistance to cracking of an organic coating on a metallic substrate when bent through 135° to 180°. The degree of adhesion may also be evaluated. Both folding and mandrel methods are considered. The folding method is more often used for practical purposes but where more precise determinations are required, the mandrel method is recommended. The cylindrical bend method may also be used for a pass/fail decision by using an agreed mandrel. The choice of the appropriate test method is limited by the thickness and/or the hardness of the substrate. The feasibility of the test depends on the type and thickness of the substrate. During the procedure, the mandrel should not deform.

This document specifies the procedure for determining the resistance to water immersion of an organic coating on a metallic substrate. The test is applicable to all kinds of organic coatings, including metallics and embossed, textured, pearlescent and printed coatings. The results of the test give an indication of the resistance of the coil coated metal to water. The method is not intended to reproduce any particular condition of condensation.