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Is there any relationship between the floating black spots or impurities on the surface of the water-based paint and the substrate wetting agent?

Update:The finished water-based paint produced has floating black spots or impurities on the surface. Many paint production tec...
Summary:18-04-2022
The finished water-based paint produced has floating black spots or impurities on the surface. Many paint production technicians have encountered similar problems, and there are "small bubbles" or small black spots in the paint production process that cannot be eliminated. Carefully inspect these "small bubbles ~ they are actually small black oil spots. Under a 20x magnifying glass, it can be seen that there is a white fine powder in the center of the oil spots.



Analyze the source of small air bubbles and small black dots:
1: The small black oil spots are usually the oil stains brought in by the filler. After replacing a batch of raw materials, the problem of the small black oil spots disappears.
2: The application effect of the finished coating with floating black oil spots is not good. Because the black small oil spots are incompatible with the coating system, the oil spots are embedded in the coating film and become defects after film formation.
3: Since the small black oil spots are a mixture of oil and powder, they are involved in the film formation of the paint, and their components are different from other components of the paint. During the drying process of the paint film, stress is generated, resulting in short cracks in the paint film around the small black oil spots. .

The workaround is as follows:
1: For the finished paint with floating black oil spots, you can add Digao 245 or Digao 270 appropriately. [Select one of the products depending on the coating system] Substrate wetting agent and an appropriate amount of emulsifier, so that the The small black oil spots are like pigment particles, which enter the coating system after adsorbing the wetting agent, and no longer affect the appearance of the coating and coating film.
2: Strengthen the quality control of raw materials.
3: In the coating formulation, try to introduce a hydrophobic dispersant, such as Digao wetting and dispersing agent, which can prevent the occurrence of this problem.