From the morphological point of view, paint defoamers are divided into solid, liquid and powder. According to the current general view, defoamers for coatings are mainly divided into three categories: mineral oil defoamers, silicone defoamers and polyether defoamers. Polyether defoamer is characterized by strong defoaming ability, strong defoaming capacity, low dosage, and does not affect the basic performance of the bubble system. And has good heat resistance, chemical stability, non-corrosive, non-toxic, not easy to burn, non-explosive.                     In addition to being aesthetically pleasing, paint forms a strong solid film, a protective coating, but it often encounters problems with foaming. The formulation uses waterborne paints, solventborne paints, various additives such as wetting and dispersing agents that make the pigments and fillers easy to wet and disperse and stabilize, and additives that improve the storage stability of the finished paint and adjust the appearance of the paint film. Additives, some of which perform special functions. Most of these coatings additives are surfactants that change the surface tension of the coating, which is an internal factor that causes the coating to blister easily. In addition, the stirring and high speed dispersion in coating manufacturing, as well as the application of spraying, roller and brush shearing during construction, can also increase the free energy of the coating system to varying degrees and generate foam, which is an external factor in generating foam. If the large amount of foam generated by the coating is not eliminated in time, it will cause various defects such as pinholes, shrinkage, fisheyes, surface orange peel, and affect the finishing and protection effect when applied on the object. It will also lead to the following serious dangers. 1. Foam can easily cause volume expansion and increase, resulting in lower equipment utilization. 2. Foam can limit the mixing speed and prolong the mixing time of the coating. 3. Foam can affect the wetting of pigments and fillers. 4. Large amounts of foam affect the packaging of the production line and interfere with packaging operations.