A Brief History of Automotive Coatings Technology

By Douglas M. Lamb

THE BIRTH OF AUTOMOTIVE COATINGS “The customer can get the Model T painted in any color he wants, so long as it’s black!”— Henry Ford, 1908. The oft-quoted statement above of Henry Ford is humorous today, but Ford was serious when he said it. In 1908, Ford thought that black car paint was the only practical automotive paint for the Model T, as it provided him with a coating that was both durable and cheap in cost. Of course, the black car paint that Ford put on his Model T actually was not “automotive” paint at all, but just the existing paint technology available at the beginning of the 20th century: a paint based on natural linseed oil resin as the binder.

Oil resins cure through oxidative crosslinking, which means the paint takes a long time to dry. Ford’s black paint was applied by hand brushing to the Model T in multiple coats, a process that, in the end, took about a week to complete. This caused a terrible production bottleneck for Ford’s innovative mass production process, even though the black paint dried faster than all other available colors. Model Ts undergoing the painting process at the end of the assembly line jammed warehouse floors of the automotive plant. This process bottleneck was the motivation for the first paint specifically developed as an automotive coating: DuPont Company’s “Duco” paint.

This new coating technology made a step change in productivity by reducing the painting and drying time from many days to a few hours. The DuPont chemists who had used nitrocellulose chemistry (Figure 1) to develop explosives and motion picture film found that if they modified the molar ratio of the NO₂ groups in the cellulose backbone, they obtained a low viscosity lacquer resin at about 15% resin solids that could be spray applied as a coating. Being a lacquer, this coating dried (merely through solvent evaporation) in about two hours.