Лако-красочные материалы — производство

4.1.1.3 Surface tension

Surface tension of liquid paint is an important characteristic that influences a number of properties of the final coating. A liquid can wet a surface only when its surface tension is lower than the sur­face free energy of the surface. Solvents play a very important role in controlling the surface tension of the vehicle as well as the final paint. Lower surface tension of the vehicle facilitates such desirable processes as wetting of pigment agglomerates during dispersion, wetting of the substrate during paint application and flow and leve­ling during paint application and film formation. It should be noted that surface tension of liquid coating is also controlled by using appropriate additives. Surface tension of the solvent is frequently measured by the du Nouy ring method or drop weight method.