Of course, these are not all the rheological behavior of liquids, however, with regard to latex paints, there are three: pseudoplasticity, thixotropy, and Newtonian flow. Each type of interaction has a different force, hence we divide shear into low shear, mid shear, and high shear.įigure 1 shows the flow behavior that can usually be achieved with various latex paint thickeners. When we act on the paint, causing it to flow, shear is applied at the interface between the paint particles and the element against which it moves (stirrer, roller, substrate, etc.). Each type of movement is described by phenomena described as shear forces. Liquid latex paints are subjected to various types of factors that set them in motion, such as mixing or spreading onto a surface. Additionally, the additives must ensure that there is no syneresis, no spattering, good leveling, etc. But the market expects latex paint to have a number of properties, and rheological additives must satisfy these expectations, including easy application with a brush, roller, or spray (especially by people who are not professional painters). The mere achievement of a resting viscosity, the so-called low-shear viscosity, is not difficult and usually comes down to a single thickener.

It is an extensive range of knowledge concerning not only rheological additives (thickeners), but their interactions with other raw materials in the formulation.ĭesigning latex paint formulations is a task that is often difficult at the stage of selecting thickeners responsible for the entire range of rheological efficiency. Rheology in its scope of research covers everything related to the flow and properties of paints during mixing, pumping, application (brush, roller, spray, etc.), or mixing after adding colorants or diluting with water. Regarding latex paints, this is the science of flowing behavior during storage and handling, both during and after application. Rheology is a lore about the flow and deformation of substances.

How to test paint viscosity