3. Practical questions about defoamers and defoaming agents

3.1 Why add solid particles to formulations?

Oils alone are capable of destroying foam, but if microscopic particles are dispersed in the oil, the antifoam's effectiveness improves significantly. The improvement comes from the effect the particles have on the first stage of the antifoam's action process, droplet entry at the air/solution interface. The effect is similar to that of a needle breaking a membrane, as shown in figure 1 . The forces are concentrated at the tip of the needle, rather than being distributed across the entire film interface. As a result, the particles present "puncture" the aqueous film, which prevents the oil from penetrating the air/solution interface. The oil...