case mod 101: how to paint your computer case (part 2)

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Anyone can spray paint their case. It’s not too hard to get a decent looking paint job from ordinary cans of spray paint. But to get a truly extreme paint job, the kind you’d see on a show car, you’ll need to apply some clear coat, and a healthy amount of elbow grease. Fortunately neither one is very expensive. The paint job we started last issue will get a finish sanding worthy of a limousine, and you’ll see how to do it, step by step.

Last time we left our modded case with a coat of gloss black enamel paint and it looked great. It was highly glossy, but it lacked the “mirror finish” of a custom hotrod. Some of the things we did in our prep were aimed at getting us set up to get that mirror shine. To get a convincing mirror effect, your surface needs to be both glossy and perfectly flat. We left off last time with our modded case under two primer coats and one color coat. That’s where we’ll pick up this time.

ready for some finish sanding

To briefly recap how we got to this state, it was removing the existing paint with 220 grit, applying primer, sanding the primer smooth with 400 grit, applying a second coat of primer, sanding that smooth with 400 grit, and applying a color coat. Every time we apply paint we pick up an “orange peel” texture. That’s inherent in using a rattle can to apply paint. Our main job in sanding is to flatten the surface. The better you flatten, the more convincing the mirror look becomes. So our next step is to sand our first color coat with 600 grit to flatten and prepare the surface for the second color coat. Unlike primer, a color coat needs to cure two to three days before being sanded. Here’s the result–our formerly glossy black panel is a uniform matte black now.

if you did it right, you won’t see dark ‘pits’

If you cut through the color coat a little like in the previous picture, that’s fine. Try to use that as an indication to back off the pressure on your snading block. 600 grit is very fine, and when the surface approaches flatness, you’ll feel the workpiece “grab” your sanding block. If you keep up strong pressure at that point, you’re likely to cut through. Low spots will show up as glossy black pits against the matte where you’ve sanded. You’ll need to dry the workpiece to see these, but they show you where you need to sand further. Work spent flattening these will pay off–otherwise they’ll show as dimples in your finish.

a few dimples left to flatten
corners are a headache–if you do your prep right you’ll see less of this

Once you’ve flattened everything down, apply your second color coat. Don’t worry about dust nibs or small bugs that land on it. These will get sanded smooth later–you’ll mess it up more by trying to fix these while the paint is wet. Make sure your second color coat is even but thick. Concentrate on areas where you cut through the first color coat. This picture shows the orange peel texture that you just finished spending all that time removing. You’ll need to repeat the 600 grit sanding step for the second coat, making sure to not cut through to primer. Don’t overapply the paint; it will be more likely to drip or form blemishes.

wet paint attracts dust hyper-magnetically
the orange peel you know and love

Again, allow your color coat to cure for a minimum of two days before you sand. After sanding the second color coat, you should have panels with a uniform matte finish, with no glossy pits. There will be visible fine scratch marks from the sandpaper. If you get any deep scratches, they will show through to the finished surface unless you take the time to fix them now. Unfortunately, that usually means sanding them out, and that can put you back all the way to applying primer again. So watch out for grit or debris on your sandpaper.

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