Flooding and floating in latex paint

Flooding and floating are problems in many paint applications. If pigment concentration is uniform on the surface but not through the thickness of the film, one refers to ‘flooding’ (horizontal separation). If, however, concentration differences are visible across the surface of the paint film, one refers to ‘floating’ (vertical separation). In this article, the influence of pigment, filler, additives, and processing conditions on the flooding and floating of colored latex paint were investigated. It was discovered that too broad a distribution of pigment and filler particle size can lead to flooding and floating. Different levels of pigment (TiO₂) or filler (kaolin) loading cause diverse degrees of flooding and floating. Waterborne coatings that do not exhibit flooding or floating may show these conditions when diluted. Using dispersants or thickeners with hydrophobic constituents, increasing viscosity, reducing surface tension, etc., all help to prevent or reduce flooding and floating. Comparison tests revealed little influence of processing conditions on flooding or floating.