What You Should Know About Car Paint
Just as the automobile has evolved during its lifetime so have the paints that protect and beautify them. Not only have the paints evolved from the original natural products to fully synthetic ones, the method of applying them has changed from hand brushing to robotic, automated methods.
In the first part of the 20th century, automobiles were painted completely by hand. The paints were natural-based (linseed oil and natural pigments) and the painting process was quite involved. It required multiple coats of paint and days of drying time. Needless to say, this part of the production process was a necessary but serious bottleneck in the automotive business.
In 1923, DuPont developed a greatly improved paint system with its “lacquer-based” paints. These new paints were applied via spray guns which speeded up vehicle assembly time. They weren’t perfect paints, though, multiple coats were still needed. Lacquers also have poor resistance to certain petroleum-based solvents. Repeated exposures to gasoline spills, for example, could damage lacquer finishes.
In the 1930s, another major development in paint technology came with “alkyd enamel” paints. Enamels were sprayed on vehicles and then were baked in ovens. The cured paint film was about 2 mils thick and it was very resistant to solvents such as gasoline. Enamel paints were quicker to apply also, typically, they were applied in 2-3 steps versus 3-4 steps for lacquers. However, alkyd enamel paints had a down side. They oxidized in direct sunlight which caused the colors to begin to show fading and/or dulling quicker sometimes in just a few months. The durability of enamel finishes was improved considerably with the introduction of “acrylic enamels” in the early 60’s. Acrylic enamels offered much improved durability and a wider range of bright, pleasing colors – especially metallics.
In the late 1970s, a new type of finish, called “Basecoat/Clearcoat,” was developed. Basically what you had was a pigmented enamel basecoat followed by an ultra-hard, clear top finish. It allowed the paint formulators to incorporate UV absorbers to protect the clearcoat from damage. Initially, the cost of the basecoat/clearcoat paint system was expensive but refinements in the paint technology helped to reduce costs. By the late 80’s this paint system had become widespread. In fact, only a small percentage of cars manufactured today do not use this Basecoat/Clearcoat paint system.
While the Basecoat/Clearcoat paint system is far superior to conventional one-coat enamel paints in many respects, it has a few disadvantages. The clearcoat has a greater tendency to show marring when rubbed by foreign materials. Finally, excessive polishing a car with clearcoat on it can remove UV protectants, which can lead to loss of gloss and clarity.