case mod 101: how to paint your computer case (part 1)
10/03/2003 One of the best ways to improve your case's looks without spending huge money is to spraypaint it. Getting serious with spraypaint is more about patience than money, but your case will still look like a million. Getting that show car shine on your case is a great way to grab serious attention. In this series of two painting articles, we'll reveal the secrets to getting your case to have the gloss of a new Benz, but for the price of a used Yugo. Professionals use compressed air and special equipment to paint. But you can get results that are just as good with a "rattlecan" and some sanding techniques. The first article will cover the proper techniques for surface preparation, and paint application. Next month's installment will deal with applying the clear coat and finish sanding. You can paint your case according to this article and have a great looking case, but by adding the finishing touches you can have the show car look that will turn heads, so make sure to read the next article as well.
Your total budget for this project will be under twenty notes (and you can do just the first portion for under ten). You'll need: a can of primer, a can of spraypaint in your choice of color, and a can of clearcoat. For surface preparation, you'll need a sheet each of 220, 320, and 400 grit wet/dry sandpaper, and a sanding block. For finish sanding, you'll need a sheet each of 600, 1000, and 1500 grit wet/dry sandpaper, plus rubbing compound. You'll also want two or three clean cotton cloths.
When you select your paints, choose a good quality spraypaint for automotive applications. Auto parts stores are the best sources because you can usually pick up your sanding materials at the same time as your paint. Use a primer and paint from the same manufacturer for the best results, and never mix lacquer with acrylic enamel, pick one system or the other. I chose to use an enamel for this project. If you're not after the show car look, and just want a rugged paint job, epoxy paint is available for extreme ruggedness.
Don't skimp on the paint, because in this project the labor will be vastly more intense than the material cost. As you can see, I spared no expense--I went for the "gray hot rod primer," which I figure should be good for at least an extra 20 MHz overclock.
You might have heard the key to successful painting is preparation (prep), and if so, you heard right. It's important in any paint job, but critical for a show car gloss. Sand down the existing paint (usually a powder coat finish with a light texture on most cases) to get as flat a surface as possible before applying our paint. To remove the beige paint, start with a 220 grit, which is fine, but has a good deal of cutting action. Sand your panels fairly aggressively in a north-south motion, but lighten when if you start to cut through the beige to metal. We don't need to remove the beige, but we do want the texture gone. Then move to a 320 grit and sand east-west with a light pressure. This will remove the scratch marks from the previous sanding, and smooth the surface.
Sand the bezel, both because we want to get rid of the texture, and because the raised lettering by the buttons will get flattened when we finish sand, so removing it during prep avoids having the beige show through. So get rid of the raised lettering or symbols on
your bezel if you have any. The key to a mirror finish is flatness, not just gloss. Without both gloss and flatness, you won't get a convincing mirror look.
And the final key to prep is cleanliness. Leaving an oily fingerprint on your panel can keep the paint from properly adhering. So can dust from sanding or just regular old crud that blows by. So work in a dust-free area as much as possible, and wipe down your sanded workpiece before applying paint or primer. Care taken here will pay of in the form of a durable, chip-resistant finish.
For each panel you're painting (plus the bezel), take them to this state of smoothness first. Primer won't fill scratches unless they're very, very fine, and the application of your color coat will make scratches pop out like neon signs, so don't take shortcuts on prep. Wet sanding keeps the sandpaper from clogging with paint particles. To properly wet sand, all you need is a shallow container with about a gallon of clean water to which you've added a couple drops of liquid dish detergent. If you have running water, that works well also. Rinse away all the paint residue and wipe the workpiece with a clean cotton rag, then set it aside to dry thoroughly.
Apply primer to your newly prepped surfaces. Pay attention to the edges, and to any areas where metal shows through the beige. Those are spots that will tend to wear, especially when you sand between coats. Get a thin first coat of primer down like in this picture.
Continue to apply thin coats to the workpieces until you've covered them completely. You'll see a flat, matte surface at this point. Let the primer dry (usually you can sand within a half hour, but check the directions on the can) and wet sand your primer coat
with 400 grit and light pressure. You'll almost certainly cut through the primer, especially around the edges. So after sanding we'll do a second primer coat.
Applying the second coat is the same technique as the first, but now you'll see the cutthrough areas, and you can direct a little extra primer towards them. Again, sand this coat with 400 grit. This will remove any overspray (paint particles that dry in midair and fall on the surface), and flatten out any dust nibs or stray insects that would mess up the flat surface.
Now break out the color coat and go insane. No, actually, you'll want to apply thin coats again, just like with the primer. Mistakes in primer are easy to sand out, but with the color coat, things like drips or scratches will be much more work to fix. So be careful to get the edges of your workpieces, and thoroughly coat them with several thin coats, leaving a finish that looks "wet." You'll still see some "orange peel" texture, this is inevitable when using rattle cans. but our next steps will be to sand the orange peel flat, and apply a couple clear coats to add gloss and protect the color coat.
You can see we're quite glossy, but not yet getting mirror-quality reflections. That's because the slight texture in the surface distorts the reflections (we're missing the flatness). So we need to let the color coat cure for a minimum of two days (some paints will continue to harden for up to a month actually, but usually you can sand within two to three days) and then go back for the fun part, finish sanding.
You can certainly stop here and have a really nice paint job. The time we spent on prep will make this a very durable finish, and it sure looks better than factory at this point. But in the next article, we'll finish sand and apply clear coat (and sand and clearcoat and sand and...) to get the ultimate finish on our panels. Check out part 2.... linear's spraypaint secrets + Buy good paint. Cheap stuff is no bargain considering how much work you'll put into finish sanding. + Follow directions on the can. You work hard to do all that finish sanding: don't get impatient, shake that rattlecan vigorously. Don't paint when it's too cold or humid. + Don't get too close to the work. Spray from eight to twelve inches from the work, and use a steady arm motion. + Don't overapply the paint. Several thin coats will be more durable than a thick coat, and look better too. + Let your paintjob cure properly before doing finish sanding. Primer is designed to be sandable in minutes, but a color or clear coat should be allowed to cure two days before you wet sand it. + Always use a sanding block. It's worth making your own from scrap 2x4 lumber if you don't want to buy one--sanding by hand will produce uneven results. + Always wet sand your work. A little bit of dish soap added to the water will help the sanding block glide over the work easily.
+ Save 600 grit and above for finish sanding. If you have another color or primer coat going on, 400 grit is as fine as you need.
case mod 101: how to paint your computer case (part 2)
10/03/2003 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.
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 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.
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.
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.
You could buff this finish out to a decent gloss. But by applying a clear coat, you'll deepen the gloss significantly. Apply the clear coat to the workpieces generously. Don't overapply, but build up several thin applications to a wet, glossy coat. Orange peel texture will be noticeable, and dust nibs will seem to be magnetically attracted, but don't worry. Again, we cure this coat for two days, then we repeat the 600 grit flattening-outthe-orange peel routine. If you cut through the clear coat, a second application is necessary, plus the two day cure before you sand again. By now you see this is not a technique for the impatient. But once you finish the flattening, you get to move up the grit scale again to scratch removal. Lightly sand with 1000 grit and then 1500 grit (and 2000 if you have some) to remove the scratches left by each previous step. This pic shows after sanding with 1500.
All that sanding work was very very tedious, but it pays off tight now. If you did a good job with the previous steps, the application of rubbing compund won't be anywhere near as difficult as if you cut corners. By now you've got a good six hours into sanding, so I know that if you're with me here, you're going the distance. And I promise that the last couple steps are a little less tedious. To buff out the fine scratches, use a high quality rubbing compound available from auto parts stores. Aplly it per the package directions, but fundamentally you rub the scratches out, leaving only a faint haze. Use only a clean, soft cotton cloth for this step. The pic shows our top panel, with one half compounded.
This is the payoff! You'll see the gloss emerge as you remove the compound from the panels. The matte finish is replaced by gloss with only a faint haze. There are swirl mark removers and glazes available where you get your paint supplies to remove the last traces of haze. You can apply these right after compounding. If you want to use an automobile wax, wait a month for the paint to fully cure first. But with the hand glaze applied, you'll have the show car look that will grab serious attention.
The bezel deserves some extra discussion. Most bezels have some curves to them, and it is more challenging to get those complex details sanded flat. Make sure you remove any raised lettering before you apply primer. If you like, you can fill holes or details with auto body filler or putty before priming. The simpler the surface is, the easier it will be to
finish sand. Rubbing compound will work its way into vent holes and other openings. Try to get your bezel as clean as possible right after applying rubbing compound.
One more pic just to show exactly how glossy this case is:
linear's finish sanding secrets + When removing scratches, use the next finest grit, and sand perpendicular to the last sanding. + Sanding on curved or detailed surfaces like your bezel may work better by hand, but use a sanding block for panels. + Be patient. Sand after your paint cures fully; it hardens significantly from the first to third days. + Dark colors give a more convincing mirror illusion. Black is the ultimate, but deep greens and blues work well too. + If using a metallic color, *do not* sand before you apply clear coat. It will ruin the effect. + use a clean soft cotton cloth for applying compound. You'll need a number of them. + Finish sanding is different than sanding between coats. Between coats, you're trying for flatness. Finish sanding is about scratch removal.