Question:
How do powder coaters ensure the best possible batch-to-batch consistency?
Answer:
Batch-to-batch consistency depends on a number of factors, such as the color, the application and the type of coating.
Powder coatings are formulated to meet color standards such as RAL. This universal color metric is used for information defining standard colors for powder coatings. The quality of the powder coating material itself is a key factor in achieving less batch-to-batch variations. Each powder coating manufacturer uses unique blend of resins, additives and pigments for a custom formulation. Better ingredients yield accurate color matches and superior results.
However, application process and equipment are also a factor in the final color/effect of the coating. An acceptance test (application trial run) must be performed on the actual application equipment before processing. The color/effect variables, particularly when powder is recycled, must first be established by producing upper and lower tolerance samples. To largely eliminate color/effect differences caused by the coating system, an entire coating job must be processed on the same coating line, without parameter fluctuations, preferably without interruptions and with consistent recycling percentages.
This relates to the type of coating used. Coating thickness is of importance as variations will cause color/effect differences. Color/effect variations inherent to metallic powder coatings can be directly linked to content of metallic pigments. Generally, fine flakes of metallic pigment are used. The positioning of the flakes within the applied coat determines the metallic effect/ color. Experience shows that all application parameters may influence the positioning of the flakes as well as color/effect. It is important that bonded metallic & 3DM are a preferred solution compared to dry blended products as the metallic flakes are consistently and evenly distributed across the surface area.
Ultimately, to ensure batch-to-batch consistency, it is important that a system and testing be in place to match color and ensure consistency. Throughout an entire coating job, all equipment must be left at precisely the same settings. Avoid coating one entire job with a variety of equipment and only after exact adjustments and comparisons produce identical test then you can compare results with different equipment and applications!
Article by Faez Kneider, National Sales Manager – Western US & Canada and General Industry Segment Manager - North America
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