When it comes to the auto body paint, we know there is one major task that a customer expects the auto body shop will fulfill. This is color match. Why is this task so challenging? To get a better insight into the problem, let’s consider what auto paints are made of and why color shifts may appear.
What are paints made of
In general, there are three ingredients that all automotive paints consist of. They are: resin, pigment and solvent.
The resin’s function is to hold together the pigment within the suspension, provide proper adhesion to the surface and make the paintwork quality and durable.
The pigment is included into the paint in the form of powder. Nowadays, about 100 colors are used in the automotive industry that can be mixed to achieve a necessary tone formula including pearl or metallic paint colors.
Solvent, the third ingredient, is designed to make the paint liquid thus providing the ability to transfer the paint from one container to another.
Along with different types of paints, there are different paint systems.
Before 1985, the vast majority of car manufacturers used single stage paint. This technology was a problem in terms of matching the original metallic colors, because it used only one layer that combined the gloss resin, metallic, pigment and solvent. Reproduction of a car’s original color was a really challenging task for painters worldwide.
This kind of paint is still used for certain purposes today, however, developed technologies made the staff’s work much easier.
Today technologies and related problems
Modern paints consist of a combination of certain pigment colors and metallic sizes. The major challenge that auto body paint staff face is meeting the factory standard. In average, each paint code has from three to seven alternates worth formulating. This big number of possible variances is the result of the fact that a car manufacturer can have up to three paint suppliers. The manufacturer takes a decision about a standard color that will be used in the production process and offers its supplier to come up with their formulas for this specific tone. The allowed tolerance for the delivered paint is plus or minus 5% maximum.
This is where the first problem is hidden because different plants of the same manufacturer may receive different paint shades for the same paint code. When compared with each other, these two colors may look completely different. This is the reason why paint manufacturers tend to provide the standard formula followed by two alternates. In case when the alternates are not available, a painter in the auto body paint shop will be required to tint the standard formula accordingly.
Metallic-related difficulties
The second reason why paint color variances occur is the metallic color applications. There are seven categories of metallic colors now: extra fine, fine, medium, medium coarse, coarse and extra coarse. Additionally, the variances occur during the process of application of those metallic colors. Color shifts can be a result of such factors as temperature, flash off time between coats, paint film thickness, fluid tip sizes, type of a painted surface (metal or plastic), speed of the spray gun, humidity and others. In general, the longer the paint dries, the darker the tone will be, because the metallic flakes tend to settle down to the paint film’s bottom pushing the pigment up and making the paint color shift darker.
Aging factors
All said above refers to variances at the car manufacturer level. Once a car has been used for several years in a range of environment conditions like sun, frost, humidity etc., the color changes inevitably. You can see the difference already 3-4 years after the car has left the plant.
Sunlight is an especially harmful environment factor. This is because it contains ultra-violet, which is absorbed by paint pigments. As a result, blue metallic colors can sometimes shift to greener shades, while red colors will turn more orange or pink.
You see now that when you want your car get painted at an auto body shop, the staff have to deal with a shifted color rather that with the one that the manufacturer presented in the original code. In most cases, if applied, the OEM color will look brighter and cleaner as compared to other body areas. Even polishing will be of no use here.
However, color matching is not the only challenge that painters face. So good paintwork, like what we do at our auto body shop in Los Angeles, is really a kind of the art.
