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A possible mechanism for defoaming by spreading is the spreading-fluid mechanism in which the oil creates a flow of the liquid in the lamella in the direction of the spreading (Marangoni flow). This causes a thinning of the lamella, resulting in the lamella breaking and the foam collapsing [3] [5] [6] [8].

Figure 3.9: Spreading fluid mechanism

Spreading of defoamer oils in lamellas has been already detected experimentally. The destabilisation of the lamella by Marangoni flow seems likely but has not yet been proven experimentally [8].