Tips for Painting your Car yourself
Painting your car doesn't have to be time consuming or difficult, but doing it the right way will be a lot of both. Whether you're feeling really ambitious or are just plain cheap, you'll need to clear a whole weekend to do this job properly.
To begin, use an orbital sander to remove the finish. Any imperfections that are visible to you now will be glaring under a new paint job, so be thorough. Sand paper that is 120-180 grit works great for this, and you'll need about ten pieces for most jobs. Avoid buying the cheap stuff - you'll work harder and longer, so it'll cost you more in the end. And, while it is possible to do this step by hand, you'll be adding countless hours to the process, so buy, borrow, or rent that orbital sander unless you've got a lot of time on your hands. Also, be sure to use an airline filter in the air hose or it'll spit water as you work. If you are sanding around parts such as trim molding or door handles that you arent going to remove, tape these areas before sanding. This allows you to get up to them with the sander without ruining the finish, but you have to be careful that you don't sand right through the tape.
Once you've sanded the vehicle, look for the shiny spots that the sander missed. These low areas need to be pulled or filled if you're hoping for a uniform paint job. If there is rust on the vehicle, the proper way to get rid of it is to cut it out and then weld new metal in, but if that's a little more than you had in mind, you can grind it out and treat it with a rust treatment. Most body repair or paint stores will have it. If you don't treat the rust inside and out, it will thrive under the shelter of your new paint and return with a vengeance sooner rather than later. Once you've treated the rust, use fiberglass to repair larger areas or gaps, while a body filler will work on smaller pinholes.
After you've treated the rust and have repaired the affected areas, fill and sand them down until they are uniform with the surrounding area. You may have to do a lot of sanding by hand to get it right, but it's worth the time spent. If you have stubborn paint chips or other shallow imperfections, use a glazing putty. Similar to a thick primer, it should be applied with a body filler knife for best results. You may have to repeat this process 3-4 times to get everything smooth and uniform, but again, the results are well worth the process.
Once you've completed the sanding and body work, finish taping. Use a high quality masking tape for best results. Covering the areas that you don't want to paint with newspaper will work, but most newspaper has pinholes spaced along the bottom edge. If you don't tape over these holes, paint will go through them and it will show up. (You can file that under "don't ask me how I know").
If you aren't familiar with how to use a spray gun, find something to practice on. You should spray in a sweeping side-to-side motion with the nozzle about 6"-8" from the surface - likewise, your spray pattern should be 6"-8" wide. Maintain a consistent distance between the nozzle and the surface. Each pass should overlap the one before it by 50%. Before you spray the primer, make sure you have that aforementioned airline filter in your air hose. Ideally you'll want to do this indoors, but this step can be accomplished outdoors on a nice day if the wind isn't blowing. Even in the most serene weather, you will have bugs, dust, and dirt land in the paint, but you have more sanding ahead that will take care of that. Be sure to consult the directions that came with your primer for details, but in general you'll want to spray 3-4 coats, waiting an hour between coats. Dry time is dependent on the kind of primer you choose, and it should be in the instructions as well. After the second coat, you'll need to wet sand the car until the primer is almost gone. (Yes, really). The primer helps to fill surface imperfections, makes the surface smooth, and gives the paint a good base to stick to. To wet sand the vehicle, wait at least an hour after spraying primer. Using 400-600 grit wet/dry sandpaper and a bucket of water or a hose, rub the surface thoroughly. You don't want to soak the car, but you want to keep the sandpaper wet. Let it dry completely before spraying more primer and wet sanding a second time.
Once you've finished that step, wipe the car down and then wash with a degreaser. Dish detergent works just fine, or someone will be glad to sell you a product made for this purpose. After you wash it down, rinse well and dry thoroughly. Do NOT touch the car with your fingers after you've washed it - fingerprints will show on the finish product through every coat of paint you put on it. Recheck the tape for adhesion. If it got too wet, it may begin to come up, but a good tape will usually be fine. Dry completely.
At this point, it's in your best interest to move inside. If you have access to a paint booth, that would be ideal, but at the very least, try to get indoors. The bugs and dust that hopped on board during the primer stage will just as quickly ruin your paint job, and it's not as easy to fix this time around. Ideally, you want the temperature to be between 65 and 90 degrees Fahrenheit with low humidity. Use reducer and thinner comparable to the temperature you're spraying in. The paint store should be able to help you with this, but briefly stated, it comes in fast, medium, or slow. Fast dries quickly for cold weather application, while slow is made for hot weather use.
Automotive paint comes two ways. The best choice for beginners is a single stage paint. Less expensive than base coat / clear coat option, you spray 3-4 coats and you're done. Less spray time leaves fewer opportunities for runs and other mistakes. Base coat / clear coat is a two stage paint that consists of the color layer and the clear or gloss layer. While it produces a deeper shine in the end, there is a lot more room for mistakes with this option. It also costs about twice as much as single stage paint.
When you're ready to paint, wipe the surface clean with a tack cloth, which removes all dust and loose material. (It will not remove fingerprint oil, so hopefully you were paying attention and didn't touch it!) If you didn't get a feel for the spray gun while working with the primer, it's a really good idea to practice on something other than your car at this point. The paint should go on thick, almost to the point of running. The key word is "almost", of course. If you play it safe and spray a thin layer, it will show texture, kind of like an orange peel. Practice, practice, practice. When you are ready, use the same spraying technique as before: the nozzle should be 6"-8" from the surface, the spray should lay 6"-8" wide, and you should overlap each sweep by 50%. Start at the top of the car and work your way down. Regardless of the kind of paint you are using, take heed of the time intervals of drying and spraying.
Once you've finished spraying and the paint is dry to the touch, remove the tape. Pull at a steep angle to the surface for a clean line removal. Doing it too soon or waiting too long will result in craggy or uneven edges.
If, despite your best efforts, you have runs or imperfections, you can usually fix them. If you used single stage paint, wait a few days to a week before lightly sanding out the run. After you sand it, buff it out. If you used a two stage paint and you have a run, you are more or less stuck with it. You can't fix it unless you sand or buff through the clear coat, so the very least you'll have to do is reapply the clear coat.
Always wait a few days before washing your new paint job. If you wash it early, use water only and a soft cloth.
The folks at the paint store are a good source of information when you have questions. They should be able to fully explain the products that are available and help you make the right choice before you buy. You're putting a lot of time and a reasonable amount of money in this project, so do your research, don't try to take the cheap way out, and with any luck you'll have something you can be proud of in the end.
