Color Sanding Process - Color Sanding To Perfection

The Paint May Be Dry, But If You Want A Show-Quality Finish Color Sanding Is A Must

Stephen Kim Jun 29, 2010 0 Comment(s)
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Rubbing sandpaper on high-dollar paint seems as logical as dropping a dumbbell on your foot right after it's been removed from a cast. Intentionally ruining what took months, or years, of agony and suffering to accomplish is just pure madness. As much as it may defy logic, scuffing up fresh paint during the color sanding process is the most effective way to eradicate tiny surface imperfections and achieve the proverbial smooth-as-glass finish. Like weeds in a meticulously groomed golf course, regardless of the painstaking efforts put forth by even the most experienced of body men to keep them at bay, orange peel, dust nibs, and fish eye divots are inevitable consequences of the painting process. To find out why this is the case, and how to go about correcting these flaws, we tagged along as Rodney Austin of Austin's Collision & Body Works subjected the hood of a Camaro to the color sanding treatment. Quite frankly, we were stunned as we watched Rodney transform what was already a fine-looking piece of steel into a paragon of automotive perfection.

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The Need To Sand
From the moment a car enters the paint booth, all the elements are working against it. While the fans and filters in a paint booth help remove the majority of airborne impurities like dirt and dust, some particulates still evade capture. "I don't care if you have a $5,000 booth or a $500,000 booth, the nature of painting a car means that you're going to end up with some dust on it. You can clean your clothes, the floor, and everything around you as best as you can, but since the paint gun is pressurized, anything floating in the air is going to stick to the paint," Rodney explains. Even uglier and more difficult to remove than dust nibs are fish eye divots, which are also the products of surface contamination. Any oil or silicon on the car's surface will cause the paint to separate, leaving behind a crater where the paint couldn't adhere to. "If you ate a cheeseburger for lunch and didn't wash your hands, you might end up with fish eyes all over the paint. That's why I don't allow WD-40 or wax anywhere in my shop. If someone's spraying WD-40 on the other side of the shop, the grease particles can still float all the way across the room and contaminate the paint."

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Perhaps the most obvious paint imperfection is orange peel, which refers to an uneven finish that resembles the skin of an orange. Except for mega-buck exotics like Lamborghinis and Bentleys that are often color sanded at the factory, every production car exhibits a certain degree of orange peel. Even if preventive measures are taken during the paint process, orange peel can be minimized but not entirely eliminated. "Paint comes out of the gun in an atomized state in the form of tiny droplets. As the droplets hit the surface of the car, the gaps between them begin to fill in," says Rodney. "This leaves a ripple effect behind. Making sure that your application technique and paint gun adjustments are spot-on will only do so much. The nature of how paint is transferred from the gun to the car will result in some amount of orange peel."

Sanding It Out
Much like sanding a block of wood, removing imperfections from paint and smoothing its surface requires hitting it with a series of abrasives. Color sanding involves sanding the paint with a very fine-grit sandpaper, followed by repeating the process with an even finer-grit sandpaper. The paint is then polished in several stages using successively finer rubbing compounds. "The very first round of sanding uses 1,000-grit sandpaper, which is just coarse enough to remove the orange peel, dust nibs, and fish eyes. In each step after that, you're just removing the scratches left behind from the previous step," Rodney explains. "With a single-stage paint, you're cutting into the paint itself, and with a dual-stage paint, you're cutting into the clearcoat. The depth of the cut is less than one mil, and the goal is to cut the surface just enough to achieve a nice uniform flatness. It takes a lot of practice and patience to color-sand, and you can burn up a panel very quickly if you get it wrong, so I highly recommend practicing on an old fender or hood before trying it out on your project car."

1008chp_15_z Color_sanding_process Hood 16/22

Furthermore, color sanding-or dry sanding-is an evolution of the wet sanding process. The end results of both are the same, but Rodney prefers color sanding. "Wet sanding is an older process where you actually lubricate the paint surface with water. Dry sanding is a newer process that's much faster since you don't have to wipe the water off of the car every few minutes to see how much progress you're making," Rodney opines. "Wet sanding is more cumbersome, since you have to use a block to make sure you're applying pressure to the paint evenly. In reality, the end result is same, but some states now have regulations that outlaw wet sanding because they don't want the sludge it creates running into storm drains. It's only a matter of time until other states adopt similar policies. Color sanding shouldn't be confused with block sanding, which is performed after laying down primer in order to remove pinholes, waves, and scratches from the surface of the body."

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Quick Notes
What We Did

Color sand the hood off of a '69 Camaro

Bottom Line
A slick, mirror-like, show-car finish

Cost (Approx)
$300 - $500

Orange Peel

To illustrate the dramatic before and after difference of color sanding, we left half of this Camaro hood untouched. As you can see from the reflections, the untreated half is stricken with orange peel and yields fuzzy reflections. The color sanded half, on the other hand, is as smooth as glass and features crisp, mirror-like reflections.

Sources

Austin's Collision & Body Works
Austin, TX
512-385-1930
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