1 Impact of expansion
The film is ruptured with a certain degree of impact. The impact of the added antifoaming agent on the bubble film can also cause the bubble film to rupture.
 
2 so that the foaming surfactant is solubilized
Certain low molecular weight materials that are well mixed with the solution can solubilize the foaming surfactant to reduce its effective concentration. Surfactants are often found to be less surface active in mixed solvents than in pure solvents. A low molecular substance that has this effect, such as octanol. It not only reduces the surface layer of surfactant, but also dissolves into the surfactant adsorption layer, reducing its adhesion. Through the above two effects, the foam stability is weakened. This is a mechanism of action of soluble antifoaming agents such as ethanol, propanol and octanol. In order to facilitate defoaming, it is often necessary to add appropriate alcohols to the silicone defoamer formulation, which also plays a certain auxiliary defoaming effect.
  
3 electrolyte disintegrating surfactant double layer
For the foaming liquid which is foamed by the double layer of the surfactant to produce foam stability, some common electrolytes are added, and some ordinary electrolytes are added to disintegrate the electric double layer of the surfactant, thereby functioning as a defoaming effect.