A History of Automotive Paint
The automotive paint industry has gone through many changes since the old days of hand brushed varnish. Paint itself is at least as old as civilized man. Cave drawings many thousands of years old at Lascaux are in color. Egyptians painted in color as witnessed by King Tut’s death mask. Greek and Roman statues, and architecture that we look upon today as stone and marble, such as the temple walls of Angkor Wat or the pagodas of Bagan, were once brilliantly painted but today only the tiniest traces remain.
By the arrival of the automobile, coach-builders had been hand painting and pin-striping horse drawn carriages for decades, and this technology was adopted by the auto industry. The first automotive paints were derived from two main natural products: the flax plant and the pine tree. Flax seeds, when crushed, produce the very slow drying linseed oil, often used by landscape and portraiture artists. The sap of a pine tree, when boiled, separates into rosin, the same substance used by violinists, and a vapor which when cooled into a liquid is called turpentine. Mix rosin and linseed oil together and the result is varnish. Add pigment and the result is a color varnish, or enamel, which is thinned with turpentine.
The earliest automobile bodies were hand-painted by brush with this enamel and it was a long and painstaking task. The paint took a long time to dry because of the linseed oil. The body finishing stage took up an enormous amount of space and time, bottle necking the whole process for any manufacturer with hopes of high production. Black enamel was found to be the fastest drying of all, and it was for this reason that Henry Ford insisted that a Model T could be had in “any color, as long as it was black.” Even so, painting a Model T still took three days. A more luxurious Packard or Cadillac, with several different colors, could take up to three months to paint. And despite all this time and effort, the average paint job didn’t last very long: about three years was normal.
Around 1915, a synthetic rosin, renamed resin, was developed which could replace the pine tree product in enamels, and paints based on natural products began their nearly century long exodus from the industry as chemicals took over. This new paint required high temperature drying booths to cure, but had a much shorter drying time of about an hour, and was much more durable than the previous enamel. It retained its shine, did not crack, and resisted weathering very well.
However, problems arose as manufacturers adopted this new technology. First, black was found to be the only pigment stable enough to accept these elevated drying temperatures, so again it was initially the sole color to be offered. The second problem was that, at the time, automobile bodies were made of steel over a wood frame, and the wood couldn’t take the high drying temperature either. That meant the only parts finished in black baked enamel were parts which had no wooden frames: hoods and fenders. The rest of the car was still finished in the much less durable varnish enamel.
As a solution, the Dodge brothers, who, after making a fortune supplying engines to Henry Ford and starting their own rival car company in 1914, quickly developed history’s first all steel car with the 1916 Dodge Tourer finished entirely in the more durable baked black enamel. That year the Dodge Company shot up to become the fourth best-selling car in America. But despite this success, all-steel bodies did not become entirely commonplace until the late nineteen thirties - witness the many different pre-war automobiles painted in colorful reds, greens or yellows, along with baked black fenders.
In 1922 DuPont introduced the first paint designed specifically as an automobile coating, meant to alleviate the production bottle neck with quick drying times while having the ability to offer a wide color selection to the buying public, who at this time were increasingly viewing the automobile as a status symbol. Duco, as it was named by DuPont, was a nitrocellulose lacquer paint that dried by rapid evaporation of solvents instead of oxidation. The solvents gave it a thin viscosity which meant it was spray-able, and with the invention of the spray gun in at this time, the 1924 Oakland was the first production car to be spray painted with lacquer. By the following year almost the entire GM line was in lacquer, as well as Chrysler, Nash, Maxwell and Studebaker. Any expensive luxury car of 20s & 30s was undoubtedly painted with nitrocellulose lacquer.
In 1926, a choice of color returned to the Model T lineup for its final two years of production. By 1928 almost all Fords used Duco lacquer, a situation which Henry Ford detested because by this time GM held some 40% of Dupont stock. For the next decade he may have had to pay his competition for the right to use this lacquer, but it at least gave a much needed shot of color to the Ford line up, helping solidify the success of the new Model A after years of black only Model T’s.
To break these chains, in 1938 Ford developed a new soy based (later coconut oil) synthetic alkyd enamel, eliminating the need to use GM held DuPont paints. This time Chrysler, Nash, Studebaker and others joined with Ford. For decades to follow Ford and Chrysler would use synthetic enamel while GM continued to use DuPont lacquer. Cadillac used lacquer paint well into the 1980s.
In the post-World War II era Germans were banned from using most explosive chemicals, including nitrocellulose, so they began the development of acrylic urethane enamels, a system that would eventually take over in North America, but not for some decades.
Around 1955 a new acrylic lacquer replaced nitrocellulose at GM. A polymer, this next paint opened up another level of vibrant color on the industry with even greater durability. Bright pastels, often two tone, dominated the GM line up. These new lacquers were particularly suited to the developing custom paint industry, as metalflake, candy apple red and other color candy coats became available.
By 1960 Ford followed suit with its own acrylic enamel to keep a level playing field with GM while still avoiding DuPont. The 1960’s also saw the widespread use of metallic paint which enhanced the curves in the cars body, although the 1929 DeSoto is thought to be the first production car to offer metallic paint.
In the 1970’s Audi developed pearl tri-coats, while Chrysler began offering mica top coats. Normal metallic paint uses aluminum flake for effect, reflecting light off each flat metal flake surface like a mirror. But mica acts as a prism - some light is reflected off and some light is transmitted through and then reflected back to the surface by other flakes, creating a vibrant, shimmering effect. More vibrant yet is the pearl tri-coat, with a depth and vibrancy unimaginable in the early years.
The 1980s was another era of revolution in the automotive paint industry. Remember the Germans? By the late seventies they had perfected a system that consisted of an acrylic urethane enamel paint base coat carrying the color pigments, followed by a clear polymer topcoat that provided unparalleled protection to the paint. This “wet look” system was another huge step forward in appearance, paint protection, durability, gloss and luster. By the mid-1980s this technology had spread across the Atlantic to dominate the North American market.
And it was the Germans again who were a step ahead in the 1990s when they developed the waterborne base coat system in Europe, with the idea of decreasing the environmental footstep of the automotive coating process. Waterborne paint made its way to Asian and finally North American manufacturers, and by the late 2000’s had come into widespread use throughout the auto industry.
What’s next isn’t apparent. But some believe our industry could be moving toward a more paintless future; that is, our urban, driverless conveyances may consist of color-infused composite panels.
Others even suggest that tomorrow’s urban vehicles could combine color-infused panels with body panels that inflate to lessen the impact on pedestrians in a collision, as demonstrated by “Flesby!” at the Toyota Commemorative museum in Nagoya.