The oil-based defoamer uses silicone oil directly as the defoamer. It is mainly used in oil-phase foaming systems where dispersants and emulsifiers are not allowed. It is generally believed that silicone oils of different viscosities exhibit different defoaming effects on the same foaming system. Low-viscosity silicone oil-type defoamers have a fast defoaming effect but poor durability, while high-viscosity silicone oil-type defoamers have a slow defoaming effect but better durability. The ointment defoamer is an ointment defoamer prepared by adding silicon dioxide, aluminum oxide and other micropowders to silicone oil, and is mainly used for defoaming in non-aqueous systems.

The defoaming effect of simethicone depends on the degree of dispersion of the silicone oil in the foaming system, the higher the degree of dispersion, the better the effect. In order to improve the degree of dispersion, mechanical stirring can be used, such as high-speed stirring under heating, or a uniform dispersion of silicone oil-mineral oil can be prepared in advance with a colloid mill. Or make silicone oil and fine powder such as white carbon black into an ointment type defoamer in advance, and use it with the help of the dispersion of fine powder such as white carbon black.