Symptoms
Contamination of the substrate (e.g. silicone, grease, wax) causes surface defects This results in areas where the coating does not cover the substrate.
Cause
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Mostly a (silicone) contamination
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Insufficiently cleaned substrate
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When spray-applied: poor functioning of oil/water separator
Solution
Sand thoroughly. Clean surface thoroughly with a suitable emulsion cleaner. Finish with a topcoat - to which an anti-crater additive can be added.