A new coil coating batch is compared to the defined standard. The graph shows measurement data taken with the BYK-mac i multi-angle spectrophotometer.
Such a “mismatch” will become very obvious when viewed from a distance. A reliable incoming QC procedure has to be defined so that panels with a different lightness flop are not assembled at the same building. The panels are either powder coated or coil coated. an important quality criterion for architectural panels. This effect is also referred to as “light-dark flop” and is e.g. Metallic finishes show a lightness change with changing viewing angle.
Special effect coatings play a dominant role in many applications as they make an object distinctively appealing: washing machines are no longer necessarily white, building facades shine in all kinds of metallic colors, and even mechanical engineering adopts the “noble” look of effect finishes. By increasing the dispersion time from 20 to 30 minutes, the tinting strength is increased by 20 %. The picture on the right shows the test results for a carbon black concentrate. As differences in gloss can be mistaken for a weaker or stronger tinting strength, care has to be taken to keep surface properties of standard and batch alike. If the batch has a tinting strength < 100 %, it means that it is weaker and more colorant is needed to achieve the required color shade. The tinting strength of the batch is determined relative to the standard and automatically displayed by the spectro2guide. The standard is assigned with a tinting strength of 100 %. Readings can be taken using an instrument with d/8 specular including or excluding or 45/0 measuring geometry. The drawdowns are measured with a spectrophotometer. In order to create a uniform drawdown the use of an automatic film applicator is highly recommended. Drawdowns are then made on opacity charts at complete hiding i.e. The procedure is based on the dilution with a defined white paint. Tinting strength of a colorant is always determined relative to a standard or reference paint of the same chemical type. Independent of the material, the optical properties of industrial coatings need to fulfill certain quality aspects before they can be applied on the final product. Increasing environmental demands during the last years and requirements for low VOC (volatile organic compounds) systems open the doors for powder coatings with 100 % solids content. Industrial coatings with lower solvent content were introduced resulting in water based systems with almost no solvent. Not only the paint batches need to be delivered with consistent quality, but also the production process of the finished product needs to be controlled.Īccording to Wikipedia the oldest transmitted paint formulation dates back to the 12th century. As many finished products consist of multiple components which are manufactured by different suppliers and at different locations, uniformity of color and appearance is crucial. Patchwork might be good for quilts but certainly not for coated industrial goods.
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