Dang surface tension high of paint coated covered Yu surface free can lower of end of material Shang, is paint surface tension and end of material surface tension difference too big Shi, easy caused paint on end of material of wetting sex bad, contact angle variable big, makes paint has keep drops-like tendencies and bare out was coated surface, especially cover light varnish and pigment copies less of color paint, compared easy appeared this defects, and not easy patch.
Shrinkage is the low surface tension of small particles or droplets of debris, they may exist on plastic substrates, coatings or flutter just well coated on the wet film. Some substances dissolved in the wet film produced with low surface tension the surface tension of a local poor Marangoni effect from the low surface tension of parts of the wet film particles away and tried to cover around the surface tension of the wet film. With the flow, volatile solvents, surface tension difference increases. Flow continues, volatile solvents increases viscosity, impede the flow and eventually formed a sunken crater.
Common solutions: using additives reduce surface tension of paint to reduce the shrinkage increased flow. It can reduce surface tension to the majority below the surface tension will cause a crater debris.