Aerosol Spray Can Painting and Prep Information

If you have an unlimited budget for your restoration project, you're probably having most of your VW's restored parts powder coated or professionally painted by an Auto Body or Restoration shop. Or maybe you have your own compressor and spray gun and some kind of "spray booth" and are doing a lot of the painting yourself. But regardless of how involved you've become in working on your restoration project, you'll still find that there are times where you can simply use a can of spray paint and end up with very professional results.

The common "rattle-can" spray paint they sell at the local Home Center or Auto Parts store can be a very useful tool for the do-it-yourself restorer. If you've ever wondered how to use a simple can of spray paint to get great paint results, check out the following tips for your spray painting projects:

1.   Not all aerosol spray paints are created equal. There are some great products out there but there's a lot of junk too. Out favorite brand is the Krylon product line which we've used with amazingly consistent and professional results. Also check out the spray products sold by SEM if you need to spray vinyl door panels, etc. Rust-Oleum also makes a quality product, but their color choices are not as extensive as Krylon's.

2.   Whichever brand you choose, it's usually best to stay with that product line for the whole project. So if you're using Krylon paint you should also use their primer and Clear Coat as well. If you don't see the exact color you need sitting on the shelf, ask the manager if you can review his product notebook so you can order the exact color you need. Krylon has a huge selection of colors, but most retailers only stock the common ones. Also, remember to buy more cans than you think you'll actually need (if you think you'll need 1 can, buy 3 instead!) - you can almost always return the unused cans for a refund.

3.   Yes you should use primer. It may seem like a waste of time, but using primer will result in a much more professional and long-lasting finish. Spraying paint directly onto bare metal and bondo just doesn't make sense, because paint as a first coat just doesn't adhere or cover as well as primer does. Usually you'll use less primer than paint, but buy the same number of cans of primer as paint, just in case.

4.   Some general tips:
      - Never try to cover the part with just 1 coat of paint - it will take at least 3 coats to do it right,
        without runs.
      - Never apply another coat unless the previous coat is dry because the paint will take days to
        dry, as the under coat attempts to outgas and dry through the smothering outer coat.
      - Pay close attention to the "recommended temperature range" printed on the side of the can.
        I once carefully sprayed 4 coats of Krylon Gloss Black on a chilly 40° day, and the next day
        when it all had dried, it looked like I had shot it with a thin coat of watered-down gray,
        splotchy milk!
      - When you get ready to pop the top off the rattle can, STOP.   The nozzle may not be in place
        or it may be barly in place and when you start shaking the can to stir up the paint, the nozzle
        could fly off never to be found again (ask me how I know this happens...). Especially when
        using a new can, carefully remove the top and make sure the nozzle is properly seated before
        you start shaking the can.
      - Always clear out the paint can's nozzle when you're done, unless you plan to use it again in the
        next 60 minutes. To clean out the nozzle, hold the can upside down, depress the nozzle (be
        careful where you aim!) and keep spraying until the sound changes and you're spraying mostly
        air instead of paint. Then stop spraying and quickly wipe off the face of the nozzle with a rag or
        your finger.
      - Spray paint and primer are potent chemicals, so to protect your health wear a respirator or work
        in a well ventilated area when spraying.
      - Also, always begin by spraying the least noticeable surfaces first (like the backside of a bus
        bumper), and working your way out to the most noticeable surfaces, so the most prominent
        areas will be free from the overspray of the earlier surfaces.
      - Be aware of the cloud of "overspray" you'll be creating, and which way the wind is blowing. You
        don't want to inadvertantly coat your wife's SUV or your neighbor's bushes with a fine mist of
        paint spots!

5.   Before applying any paint, you first have to prepare the part. Any scratches or dents you ignore will not be "hidden" by painting, and in fact most gloss finishes will actually tend to highlight these imperfections! So make sure the part is really smooth and scratch-free before breaking out the spray paint. We'll cover all this prep stuff in another article, but for now let's assume you've taken care of all the imperfections you can. The last thing you should do is sand the part thoroughly with 200 grit paper. This grit is fine enough to smooth out most surface scratches, yet still leave a microscopic texture to give the primer a little "tooth" to stick to.

6.   Once the sanding is done, put on some safety goggles to protect your eyes, and then blow off the part with compressed air. Get in all the crevices and joints (use an ice pick or utility knife blade to free up the junk in the tight areas - like the tight joints on a wheel, then blow the particles out) to get rid of all the sanding dust and junk. If you don't have an air compressor, buy an aerosol can of compressed air from an Auto Parts store or Electronics Supply store (these cans of compressed air are really handy. Attach the long red tube to the nozzle and then blow off the parts with short, quick bursts of air. But watch out, because if you hold the red tube too close to the part, or hold down the nozzle for longer than a quick burst it will actually spray "condensation" moisture on your part!).

7.   For the final cleaning, you have to "tack" (i.e., wipe down) the part with the proper solvent. Most cans of spray paint and primer (including Krylon) are lacquer based products, so always use lacquer thinner (never use paint thinner (AKA mineral spirits or turpentine) before spraying a lacquer-based spray product or you'll end up with lots of "fish eye" defects in the finish). Take a quality paper towel, wet part of it with lacquer thinner and carefully wipe the part down. Start with the "least visible" surfaces and work your way out to the most visible surfaces. Turn and fold the towel often so you're always using a clean part of the towel and keep refreshing it with lacquer thinner. As much as possible, try to not touch the wiped down surfaces with your bare hands. Really try to keep dust, dirt and your fingers, off the cleaned part. Don't use a fuzzy rag or thick paper towel for this "tacking" step or you'll likely end up with a bunch of fuzz all over the cleaned surface. Use a quality paper towel or an old cotton t-shirt. Get close to the part, really look it over and if you still see any fuzz, dust or hairs, lightly blow it off again with compressed air and re-tack the surface (if necessary). If there are some patches of old paint on the part you're working on, don't rub these spots with too much lacquer thinner because you could slightly "melt" this old paint and mess up the smooth surface (if this happens, just let the lacquer thinner dry and then lightly sand the bubbled old paint so it's smooth again).

8.   Now let's get ready to spray, by figuring out how to hold the part while you spray it. If at all possible, try to do the painting outside. If it's too wet, windy or dark outside, find a well-lit area in your garage or shop, with good ventilation. The best painting configuration for large objects (bus bumpers, engine tin...) is to try to hang the part from a bent piece of coat hanger suspended from a tree limb or a beam in your shop. Small parts can be set on a box or saw horse. Never set the part on the shop floor because it's awkward to kneel down and paint, and the spray will dredge up dust off the floor and fling it up onto the newly sprayed wet paint. Small parts like nuts and bolts can just be set on top of the box and screws can be threaded a little ways into holes in the cardboard. Medium sized parts (like the crank pulley, or bumper brackets) should be set on small wooden blocks so secondary spray doesn't bounce off the surface of the box, onto the wet part. Position the part so you're spraying the least important surface first (like the backside and bottom surface of a bus bumper).

9.   Begin with the primer. Shake the can well (for at least 60 seconds) so you really hear the mixing ball rattling around inside. To begin spraying, hold the can about 8" from the surface to be sprayed, start off to the side of the part, hold down the spray nozzle so you're spraying at a right-angle to the surface, and make a 12" sweep across the part by moving your body and arm along the part so the nozzle is always about 8" from the surface, then release the nozzle. Now press the nozzle down and make another pass in the opposite direction and release the nozzle. Keep repeating these long sweeps in smooth consistent swaths as you work across the part. Sweep too quickly and paint won't coat the part. Sweep too slowly and you'll create puddles that may run. This is the primer, so we're not gonna load it on too thick. Walk around the part and spray all the surfaces you can reach without moving the part - spraying the most important areas last. Don't overlook the crevices and hidden pockets and make sure you coat everywhere you can see. This first coat should be thin, and you'll still see the part's surface (old paint, bondo, shiny metal...) through this coat of primer. Because it's primer and because it's a thin coat, it will try quickly. So after about 10 minutes, shake the can of primer again and begin applying the second coat exactly as you did the first, but now you should make your sweeps a little slower and hold the can a little closer to the part, because you want this coat to be thicker than the first. Spray this coat to just cover the part's original color, but not much thicker. Now walk away from the part, and clear the nozzle by turning the can upside and spraying primer (careful where you aim!) until the sound changes and you don't see much color coming out anymore (about 3 seconds) then quickly wipe off the face of the nozzle to remove the wet primer. Let the second coat dry for at least 30 minutes, shake the can again and spray on the third and final coat of primer. This coat should be a little thicker than the second coat so the part has a nice consistent coat all over. Your part should now be all "primer colored" with nothing showing through. Let the primed part dry for at least several hours (over night is even better) and then lightly sand the surfaces with 200 grit paper to knock off any fuzzies, bugs, dust or stray hair that may have landed in the wet primer. When sanding, be careful at the edges, because the coating will be thinner there and it's hard to avoid sanding right through the primer, down to the metal. Now turn the part over and check the un-primered topside. There will be a little primer overspray so sand these bare surfaces lightly to get then smooth again. Now dust off the part, especially the bare surfaces we need to prime now. Position the part so you can prime these final surfaces (these will be the most prominent areas; like the top and outside of a bus bumper). Now grab the primer and coat these topside surfaces, exactly like you did the backside surfaces (i.e., 3 coats, let dry between each coat, lightly sand the next day...).

10.   Now it's time to apply the paint to your primed part. The procedure for applying the paint coats is very similar to applying the prime coats. Again you'll be spraying 3 coats and you'll want to begin by spraying the least noticeable surfaces first. But there are differences here; the paint coats will take longer to dry (especially the second and third coats) than the primer coats did, so make sure a coat is really dry (by lightly touching an inconspicuous area to see if the paint is still tacky) before spraying on the next coat. But the main difference comes with the final coat. With primer, you're obviously not trying to build up a glossy coat, but with paint you are. When spraying the final coat of paint, you'll want to use shorter sweeps and move a little slower to leave a high gloss finish. This is tricky because if you load the paint on too heavily it will sag or run, but if you spray too light a coat, the surface will end up with a dull sheen. So, for this last coat you want to spray back and forth in 6" sweeps just until the finish starts to look wet and shiny, then stop and move on to the next area. It will take practice to get the high gloss without the runs and sags but it's not too hard to learn. One final caution about overspray; when you spray an area and then move onto the next area and start spraying, the overspray will tend to waft over onto the previous area and dull out the great gloss you had there. To minimize this effect, plan your spraying strategy carefully so you spray in a linear sequence and angle the nozzle slightly so you tend to spray towards the new area and away from the previous area. If you do end up dulling the edge of the previous area a little, don't go back and re-spray that area because you'll probably trigger runs and sags. Instead, just move on because you can bring back the gloss later during the polishing/waxing steps. After spraying the final coat, back away slowly to avoid stirring up dust. If the part is hanging safely in your shop, just leave it alone to dry. If the part is outside, let it dry for 30 to 60 minutes then move it indoors so it can thoroughly dry away for the elements.

11.   The paint will probably be dry the next day, but I usually wait several days before handling the newly painted part. At this point you can install the little beauty, but you may want to rub out the new paint first. If you were able to get a nice gloss finish with the final coat of paint, you might want to just leave it alone, but if you have some dull areas or an "orange peel" texture, break out the polishing compound (More Info Here) and wax. Use the polishing compound sparingly on a soft damp rag and rub lightly in a back and forth motion to even-out any slight irregularities and get rid of the "orange peel". Avoid sharp edges and creases where the paint is thinner and don't get carried away here and rub through the paint or you'll have to do a repaint! After you're done with the polishing compound, use Meguiar's "Mirror Glaze #7" polish to remove the microscopic scratches left by the polishing compound, and bring back a glossier finish. Then follow this up with a coat of Meguiar's "Gold Class" wax.

12.   One final note; to achieve a super high gloss finish; you can skip the polishing and waxing steps, and instead lightly sand the final paint coat with 600 grit paper (only if it has imperfections that must be "sanded out"), then thoroughly blow off the part with compressed air, and then spray on several layers of "clear coat". This works great for small interior parts, but for exterior parts the clear coat will eventually flake off in the sun, so we don't recommend this clear coat technique for exterior parts.