Someone has studied the defoaming process of polysiloxane in the oil system.They continuously take pictures of the foam system at a speed of 1/1000 second, the picture is enlarged 100 times, and the schematic diagram of the 4 consecutive pictures can be seen. Drops reach the bubble film, rupture the bubble film surface and merge into large bubbles, from 1 to 3, the foam merges from 4 into 1 large, and the bubble film becomes thin. At last, the gas-liquid separation was rapid, the large bubbles were eliminated, and the breaking of bubbles reached the end of 4. This also objectively explains why a drop of antifoam goes down and a series of bubbles burst.

When the defoamer adheres to the bubble film, it is immersed in the bubble film liquid, which will significantly reduce the surface tension there. Because in the water system, the active ingredient of the defoaming agent has a low solubility in water, the reduction of surface tension is limited to the local part of the bubble film, and the surface tension around the bubble film has hardly changed. The part with reduced surface tension is strongly pulled and stretched around, and finally causes the foam to burst.