Oil type antifoaming agent is directly used silicone oil as an antifoaming agent. It is mainly used in oil-phase foaming systems that do not allow the presence of dispersants and emulsifiers. It is generally believed that silicone oils of different viscosities exhibit different defoaming effects on the same foaming system. The low-viscosity silicone oil-based defoamer has a fast defoaming effect, but the durability is poor, while the high-viscosity silicone oil-based defoamer has a slow defoaming effect, but has a good persistence. Ointment type defoamer is a defoamer in the form of an ointment formulated by adding silicon dioxide, alumina, and other fine powders to silicone oil. It is mainly used for defoaming in non-aqueous systems.

The defoaming effect of dimethyl silicone oil depends on the degree of dispersion of silicone oil in the foaming system. The higher the degree of dispersion, the better the cannon effect. In order to increase the degree of dispersion, mechanical stirring, such as high-speed stirring under heating, or a colloid mill, is used to configure a uniform dispersion of silicone oil and mineral oil. Alternatively, a silicone oil and a fine powder such as white carbon black are prepared in advance as an ointment type defoamer, and used by virtue of the dispersion of the fine powder such as white carbon black.