For the first quarter of the 20thcentury almost all automobile bodies were painted by hand, with brushes. Nothing held back car production, like painting. It was the manacle, the iron boot of the industry. Paint technology had not kept up with advances in other areas of mass production. Major automakers could assemble a car in four to five hours, but it took three to eight weeks to paint it. Into the 1920s many car bodies were built by independent suppliers.

Click on the link to read the complete article 1pdf How cars got colours