Water base paint is the most eco friendly choice for modern coating solutions. However it’s not just a simple replacing of paint to fit directly with existing painting line system. Some crucial parts has to be configured separately in order to follow its specific requirements. Here we introduce 3 most crucial parts of water base paint application.
Paint Mixing & Piping
Water is corrosive medium for metal. It will lead to equipment damage and generate metal ions, which will not only make the paint film yellow but also reduce its anti-corrosion ability. For this reason, the water base paint container and pipeline should be made of stainless steel and should be chemically passivated. Low shear type model should be selected for the paint mixing system, mixer and back pressure regulating valve. The paint pipeline connection should avoid dead angle with bigger diameter pipes to increase the pressure and liquid flow of pump. The paint circulation speed should be 0.15m/s paint mixing room temperature should be controlled below (3±1)℃ of the paint. Storage stability conditions of water-based paint: 5 ~ 30 ℃ / 6 months.
Electrostatic painting
The resistance of water-based paint is less than 0.1M, there is high voltage leakage. Dedicated electrostatic spraying equipment should be used. Usually we suggest an external electric paint transfer system since the pipeline and color change are the same way of traditional setup. We suggest electrostatic bell for maximum paint efficiency and finishing quality. If it’s conventional gun, it must be water base spray gun or else it will break in short time. Water base spray gun is all stainless steel production which is abrasion resistant, it can be used for both solvent-based and water-based paints at the same time.
Dryer oven
The water evaporation rate in water-based coating is low, the flash off or drying time is related to humidity. Before spraying solvent-based top coats, it is necessary to control the residues under 10% in the base paint. Reduce the humidity during flash off or drying and improve the water evaporation rate. Heat at low temperature with blow to prevent sagging. Ideally to use infrared heating at 60 to 80°C and keep the temperature for 2 to 3 minutes. The cooling tactic should be adopted to reduce the humidity in flash off chamber.
Either the dryer chamber or the hot air mixing fan, we should use stainless steel for water base paint dryer design. Because the steel material can be rusted quickly by water evaporation. Stainless steel 304 is suggested.
