Post Rinse Process for Electrocoated Parts
As the painted part exits the electrocoat bath, undeposited paint clings to its surface. This undeposited paint is commonly referred to as drag-out or cream coat, and multiple rinse stages are usually incorporated into the system design for its removal and improvement of the final aesthetic appearance of the part. Whereas the cream coat will be rinsed away, the electrodeposited paint has bonded with the surface and will remain intact during the post rinsing process.
Post rinsing stages are in a closed loop with the paint tank, as they are continuously being fed with fresh ultrafilter permeate from the paint tank. As they fill up, they either gravity or mechanically overflow to the prior rinse stage and eventually the paint tank. The end result is a painting process that has an application transfer efficiency of over 98%, as almost all of the drag out or cream coat is captured in the post rinses and returned to the paint tank.
Some systems also make use of a final post rinse stage that is made of deionized water. Although not part of the closed loop rinsing process where cream coat solids are recovered, and not required when the electrocoat will be top coated, a final deionized water rinse will help to improve the appearance of an electrocoat finish.