Why are black spots or impurities floating on the surface of finished paint

Problem: there are floating black spots or impurities on the surface of the finished coating Many coating production technicians have encountered similar problems There are "small bubbles" or small black spots in the coating production process that cannot be eliminated Carefully inspect these "small bubbles" ～ in fact, they are small black oil spots Under 20 times magnifying glass, white fine powder material can be seen in the center of oil point Analysis: small black oil spots are usually oil stains brought in by fillers When a batch of raw materials are replaced, the problem of small black oil spots disappears The application effect of the floating black oil spot is not good Because the black oil spot is not compatible with the coating system, the oil spot inlaid in the film becomes a defect Because the small black oil point is a mixture of oil and powder, which is involved in the film-forming process of the paint, its composition is different from other components of the paint, and the stress is generated in the drying process of the film, resulting in short cracks in the film around the small black oil point Solution: for the finished coating with floating black small oil spots, the base material wetting agent and appropriate emulsifier can be added appropriately, so that the black small oil spots without tank capacity are like pigment particles, and enter the coating system after the wetting agent is adsorbed, which will no longer affect the appearance of the coating and film Avoid methods: 1 Strengthen the quality control of raw materials 2 In the paint formulation, try to introduce hydrophobic dispersant to prevent this problem