(* we did NOT paint the vehicle above, I found the photo on the internet)
Why is auto paint color match such a difficult task?
Automotive Paint Colors: What affects color match?
In this article I will be discussing the main factors of why color match is such a difficult task. I believe if you can grasp a little bit about what auto paint colors are made of and how their application shifts color, then you could understand what causes color to change and what you need to do to match them.
There are three basic ingredients in automotive paint:
The resin is the component that holds together the pigment in suspension, provides adhesion to the surface applied, and determines the quality and paint durability.
The pigment comes in a powder form similar to concrete, and the average aftermarket automotive paint mixing system includes about 100 colors or toners to be able to mix formulas including metallic and pearl paint colors.
The solvent is what provides the transferability, without the solvent the paint would be to thick in viscosity to transfer from container to container.
So what affects color match? Now that you know the ingredients of automotive paint, I will explain what happens to color during the application.
Auto paint colors are made up of a combination of pigment colors and metallic sizes including pearls. The first challenge is the factory standard. Today, the average paint code has between three to seven alternates that are worth formulating. There is actually more but the auto paint manufacturers have narrowed them to down to keep the databases simple to use.
So why do the car manufacturers have so many variances? Most car manufacturers have three major paint suppliers. The manufacturer decides on a standard color for production and submits a painted sample to their suppliers. The paint manufacturer then produces a formula for the “standard sample” and is allowed a tolerance of plus or minus 5% when they deliver the paint.
This is the first problem because the plant in the east coast may be getting a 5% shade greener on a blue metallic standard and the plant in the west coast may be getting a 5% shade violet on the same blue metallic standard. When compared side by side, they look like a completely different color. This is the reason the paint manufacturers usually have the standard formula followed by two alternates. If the alternates are not available, the painter in the body shop usually mixes the standard formula and tints it accordingly.
The second reason for variances in paint colors is the metallic color applications. The metallic colors are now classified in 7 categories. Extra fine, fine, medium, medium coarse, coarse, and extra coarse. The metallic colors control the value (lightness and darkness) of the color similar to what white does in a pastel color.
Metallic colors will cause variances in color when applied. Temperature, paint film thickness, flash off time between coats, fluid tip sizes, speed of the spray gun, surface type (Plastic or Metal) and humidity will all cause the color to shift lighter or darker.
Why do plastic bumper covers change color? Every once in a while we are trying to deliver a car and the customer will not take it because the bumper looks different than the car. The most amazing thing is that the bumper and the front end of the car was painted at the same time, with the same gun, same air pressure, same temperature and the same paint.
How do you explain the bumper color change to the customer? Plastic bumpers will always change color especially in metallic colors. The plastic has a static charge and the metallic paint will settle different than on the sheet metal parts, causing pigment flotation that will shift the color darker or lighter. The other reason is surface temperature, if the sheet metal is colder, the bumper will look lighter, if the sheet metal is hotter than the bumper, the color on the bumper will look darker. The third reason is flex additive. If the clear coat is applied on the bumper with a flex additive, it will shift the color slightly.
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