Coatings Cafe
Dewetting
Defect Description
The Dewetting defect happens when the surface tension of the paint is not balanced with the surface tension of the substrate causing uneven flow.
The Paint must have lower a surface tension than the substrate for good flow and leveling. If the paint surface tension is too high—higher than the substrate then the paint not “wet” and flow evenly over the substrate. If this surface tension balance is off the paint will forms areas of high film surrounded by areas of almost no paint. The paint can initially appear in the wet to form an even coat, but then “retract” or “crawl” to form islands of paint.
Also known as: crawling, retraction
Possible Causes of Defect
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1. Substrate is contaminated with a hydrocarbon oil
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2. Paint has not been mixed properly
Tips to Avoid Defect
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1. Practice good house keeping with cleaning and maintenance materials
2. Mix paints before use, even clearcoats