The dipping process is important for the continuous coating of mass-produced large and small objects ranging, for example, from motor cars to oil cans. It has advantages over the spray method of low labour cost and greater economy in consumption of paint. The paint is contained in a dip tank which is stirred or agitated to maintain uniformity of paint and frequent checking of solids content, viscosity and temperature need to be carried out to prevent augmentation, settling out and maintain even film thickness.

The article is immersed into the dip tank and withdrawn at an even rate. Because there is an amount of flow to the paint, the top of the article generally has a reduced film thickness, while the bottom has an increased film thickness.

To overcome this defect, ‘Rotodip‘ processes were introduced where special machinery consisting essentially of a rotating framework which holds the article to be coated, carries it into and out of the paint and enables final drainage to take place in such a way that the overall even-mess is much improved by rotation of the article. The process was much used for priming of motor car bodies, but has been superseded by the electro painting process.