Measuring the dynamic surface tension of water-based paints and coatings.
Water-based paints and coatings contain additives in order to decrease their surface tension. Two main tasks have to be considered when spraying paint:
1. Wetting
An optimal wetting can only take place if the surface tension of the liquid paint is lower than the surface tension of the substrate while contacting. Spraying is a time critical wetting process; thus, it is important to pay attention to the choice of surfactants and especially to the surfactant's dynamics.
2. Surface and spreading defects
The surface tension of paint has to be reduced by using additives in order to improve the appearance of the coating film and to avoid defects on the surface. Furthermore, possible surface and spreading defects while drying (for example floating, pinholes, scratches) can be stemmed through the surface tension of paint. A precise co-ordination of the dynamic behaviour of the surface tension is very important for spray applications because the surface tension has to be reduced to the required level within a short time in order to achieve an optimal wetting.
Those required test results are received professionally within a short time by using innovative bubble pressure tensiometers of SITA Messtechnik GmbH.