Foam control additives defoamers, antifoaming agents, antibubble additives, foam suppressants

Anybody knows: * Bubbles of air in paint leading to unaesthetic defects after drying. * Water boiling over when cooking pasta. * Foaming of soap and detergent solutions… All these common facts are related to air or vapours emulsifying in liquids. The problem is industrially very important and has expensive consequences for numerous sectors as diversified as paints or varnishes up to food industry or machining. Foam-control additives are used to minimize or suppress this phenomenon. Foams are due to the dispersion of tiny particles of gas into a liquid medium. Most of the pure liquids and gases cannot foam naturally and if gas is incorporated into the liquid, the nascent bubbles collapse immediately. The presence of surfactants is essential to obtain a stable foam. Often these surfactants are not deliberately added to the liquid but come from other ingredients. Taking a trivial example, pure water does not foam when boiling, but if pasta are suddenly added in boiling water there is a copious formation of foam and …the water boils over.