Mixtures of triolein with stearic acid were significantly less effective as antifoams than mixtures with tristearin. Measurements of contact angles at oil-water and air-water surfaces combined with consideration of crystal morphology have permitted exploration of the possibility that these differences concern the relative effectiveness of particles in rupturing triolein-water-air pseudoemulsion films. No significant difference in the theoretical effectiveness of tristearin and stearic acid in their potential to rupture pseudoemulsion films is however apparent. This suggests that the earlier finding that relative antifoam effectiveness rather concerned particle size and aggregation where stearic acid particles were, for example, more than an order of magnitude larger than the tristearin particles, implying lower probabilities of presence in drops and films.