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Origin and Potential Causes:
· "Piling on" the undercoat in heavy and wet coats. Solvent is trapped in undercoat layers which have not had sufficient time to set up.
· Material not uniformly mixed. Because of the high pigment content of primer- surfacers, it is possible for settling to occur after it has been thinned.
· Improper thinner/reducer selection.
· Improper surface cleaning. When not properly cleaned, primer- surfacer coats may crawl or draw away from the edge because of poor wetting and adhesion.
· Improper drying. Fanning with a spray gun after the primer- surfacer is applied will result in drying the surface before solvent or air from the lower layers is released.
Finishing grit of sandpaper too coarse.
Prevention Techniques:
· Apply properly reduced primer- surfacer in thin to medium coats following recommended flash off time between coats.
· Stir all pigmented undercoats and topcoats thoroughly. shop conditions. · Thoroughly clean areas to be painted before sanding.
· Use proper sandpaper grit before applying polyesters or undercoats. · Follow product recommendations per its Technical Data Sheet
Remedy:
· Thoroughly dry affected area. · Sand, isolate if necessary, and refinish.
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