5 января, 2016 
Pokraskin Foam is a gas, usually air, that has been dispersed and stabilized in a liquid. Air may get incorporated in coatings during manufacturing (such as by agitation) or during application (such as by spraying or brushing). Foam may also be produced when paint is applied on porous substrates such as wood or mineral surfaces as a result of displacement of air from the pores by the liquid. Foam occurs more commonly in waterbased coatings. Coating formulations contain surface-active agents for various reasons, such as emulsifying agents in waterbased binders, wetting and dispersing agents, and substrate wetting agents. These surfactants may stabilize air in the form of foams.
Foam is always undesirable in coatings at any stage. Foam in the mill base during the pigment grinding stage acts as a cushion and hence reduces the stress transformation to pigment agglomerates that is necessary to break them apart. Foam may also create difficulty in filling cans with the correct amount of coating. Foam generated during the application process may lead to defects in films such as pinholes, craters or cissing. Apart from optical defects, foaming — even microfoam — may reduce the performance and protective properties of the coatings.
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