Foam breaking anionic surfactants

The wash temperature has a significant effect on foaming due to its effect on the solubility of the defoaming surfactant. Nonionic surfactants are only effective above their cloud points. Careful consideration must therefore be taken when formulating with nonionics. Water hardness also plays a role in foam formation. In hard water, Ca2+ and Mg2+ form complexes with fats or anionic surfactants. These insoluble complexes interact with the foam, breaking up the micellar structure. 

Table I shows the initial foam height, h°, and the foam half-life, rl/2, in the presence of different types of antifoams. The oil alone has low, foam-breaking efficiency (high initial foam height and half-life), the hydro-phobic particles alone are more effective, and the mixed type of agent is much better antifoam. The synergism between the oil and the hydrophobic solids is a general phenomenon. It generally occurs independently from the nature of the nonpolar oil (silicone or hydrocarbon oil) and the nature of the surfactant solution (anionic, cationic, or nonionic) (86, 88).

---