Painting a car is one of the most misunderstood parts of our hobby. It can be a daunting process to sand off the paint on your car, determine what primer to use on the car and then paint and finish it, but it’s one of those jobs where things must get worse to get better. Below are the basic steps and methods for painting your car along with what you should use for certain situations.
Preparing a Car for Painting
There are a few ways to prepare your vehicle for paint. Each method depends on how extreme you’re going with your paint job or restoration. The most common methods are below.
Strip to Bare Metal
This truly is the most “correct” way to prep a vehicle for repainting, especially a classic or “older” car. This method will allow you to uncover any potential rust or corrosion that will need to be addressed before you put on any top coats. Below are the most common methods used to strip a vehicle to bare metal before painting.
- Stripping or Cleaning Disc – These come in a couple of sizes and are good for removing paint in large areas (hood, roof, fenders, etc.) or in small areas (like body lines, engine bays, etc.) without damaging the metal.
- Media Blasting– Media Blasting is a popular method to quickly remove paint, primer, and rust by shooting the metal with pressurized finely ground abrasive media. This method requires an air compressor and extreme care must be taken to avoid warping the body panels.
- Chemical Stripping – This method is applied by brushing the liquid stripper on the metal. You must then allow the chemical to slowly soften and lift the paint. You can then use a scraper or wire wheel to remove the softened paint. We suggest using a DA sander to “break the surface” before applying the stripper to help speed up the process. Services are also available to have a vehicle “dipped” in an acidic solution that will remove all prior coatings and completely bring the vehicle to a true “virgin” state.
Scuff and Shoot
This method isn’t the most optimal, but it’s common in quick repairs or repaints. We suggest avoiding this method unless you know the base coatings left below are solid and the metal is free of corrosion. You must abrade the large surfaces with 400-600 grit sandpaper on a block or with a DA sander before you apply any new coatings to the vehicle. The texture left by sanding the surface will give the new coatings something to adhere to when applied.
- Air Sander – Using an air sander or DA sander will allow you to quickly abrade the existing paint and give the surface the texture needed for the primer or paint to “bite” into. This method is the quickest for a “scuff and shoot” but it also tends to leave an uneven surface that will affect the finished paintjob (wavy finish). For the best results we suggest using a DA in conjunction with a block sander.
- Block Sanding – This is the slower, more labor-intensive manor of preparing a vehicle for paint, but it allows you to leave a flat, uniform base for paint to be applied to. There is a plethora of block sanders, so make sure you pick the appropriate block for the shape you’re sanding. Check out the different types here.
Repairing Body Damage
Before repainting a car, we suggest trying to repair any damage found on the body. This includes rust, dents, paint chips, etc. The more time you spend fixing damage on the car, the better your final paint job will look when it’s done. Below are a few of the essential methods and tools needed to repair body before a paint job.
- Hammer and Dollies – Using a hammer and dolly is the most basic way to repair dents and is also the most common. By hammering on the damaged area while holding the dolly behind the damaged area (or adjacent to it called hammering “off-dolly”) you can bring the metal back to its original shape. We’d suggest picking up a basic hammer and dolly kit like those we offer. Beginners and seasoned vets alike can benefit from picking up a copy of The Key to Metal Bumping to help learn how to correctly attack a dent with a hammer and dolly.
- Stud Welder – A stud welder is another method used for pulling dents in metal. This process is simple but does take some practice to perfect. It involves using a tool to spot weld small pins to the damaged area. You then use a slide hammer to pull the pins and dented metal out. Once you have pulled the dent out you can cut the pins off and grind the surface smooth. We suggest using this method on panels where a dolly can’t get behind the panel. If you already have a MIG welder you can save money and time by purchasing a MIG stud weld kit.
- Inflatable Dent Removers – These are like balloons on steroids. Place the inflatable dent remover behind a dented or damaged body panel and slowly inflate it. The pressure of the dent remover pressing between the dented panel and the inside structure of the body will force the low or dented areas up. This works well for shallow dents but will not take out deep or creased dents. Check out our alternative dent removal tools here.
- Body Filler – Once you’ve fixed the dents or damage to the best of your ability, you’re ready to apply body filler over any small imperfections in the body. Body filler is most commonly available in a “plastic” version, but lead or metal type fillers are available for specialized repairs. Additionally, glazing putties can be used for filling small pinholes or minor imperfections as they are thinner and flow out easier than normal body fillers. For more extreme repairs where normal body filler can’t be used, reinforced fiberglass body filler can be applied to “build up” a damaged or “low” area. We suggest using body filler sparingly and only to smooth out small imperfections in the body. It should not be used to fill in bodylines or trim holes as it can fail over time. Prep the area (bare metal or epoxy primer) with 60-80 grit sandpaper so the filler has a good texture to adhere to.
After you have stripped off the old paint, abraded the surface and fixed body damage, you can now move on to sealing up the surface by applying a primer to the vehicle before applying color. But there are several questions that come up when choosing primer to use on a car. What surface am I applying primer to? Are there still imperfections in the body or chassis? What automotive primer should I use over old paint? This last question is most important, as the type of primer you use primarily depends on how far you’ve gone with removing the old paint. Below are the common types of primer used when repainting a car.
- Epoxy Primer – Epoxy primer is one of the most versatile primers available as it’s compatible with most any other coating. It’s acceptable for use over bare metal or existing coatings. Epoxy primer is necessary when you have any bare metal exposed on your project. We suggest first abrading the entire area you’re priming with 80-120 grit sandpaper. Surfaces coated with epoxy primer can also have plastic body filler applied over it if properly prepared. The only major downside is that many epoxy primers are not California VOC compliant. Make sure you check compatibility with other primers, as some primers (self-etching primers, for instance) do not play well with epoxy primer.
- Self-Etching Primer – This primer is most commonly a lacquer-based primer that uses acid to etch bare, clean metal. It leaves a good base for urethane primers and top coats and is ideal for small spot repairs. When applied over properly prepared metal, it has extremely good adhesion qualities. However, it can’t be used around or over enamel based coatings, as it can cause lifting. Do not apply body filler over top of self-etching primer as it may cause separation of the filler over time. We suggest sanding the metal with 80-120 grit sandpaper before applying self-etching Primer.
- Sprayable Polyester Primer – This primer is as close to sprayable body filler as you can get. It builds extremely well, fills minor imperfections in your bodywork and can be block-sanded flat like your body fillers. This can be applied over your epoxy or self-etching primer and body filler. Use poly primer as your final step in the “bodywork” stage to get your panels laser-straight.
- Urethane Primer Surfacer – Urethane primer is the next coating you should use after epoxy or self-etching primer and filler. This is where you will really want the bodywork to become nice and flat. Urethane primer surfacer can be used alone over existing coatings if you’re doing a “scuff and shoot” type paint job. We suggest finishing the surface with 180-220 grit sandpaper before applying urethane primer. Check out our high quality urethane primers here.
Color and Top Coats
At this point, you’ve fixed all of the old dents, rust and damage, and you’ve primed and block-sanded the entire area you’re painting. Now you’re ready to lay down the color and (if you so desire) clear coat. We’ll cover the steps and products you’ll need to get a fresh, shiny coat of paint and clear on your vehicle below. Note the surface you lay paint over must be abraded in steps from 320 to 600 grit before you apply paint. Be sure to use PRE™ or similar paint prep and a tack cloth to remove any grease or residue leftover from preparing the vehicle for paint.
- Single-Stage Paint – This type of paint is the simplest to apply and is also the most affordable as it does not require a clear coat. Single stage urethane paints still have UV resistance and can shine similar to a clear-coated vehicle if maintained properly. All vehicles had a type of single-stage paint up until the early 1980’s when the base coat/clear coat system was developed. You’ll want to apply 2-4 coats of paint depending on the desired final look and the type of paint you’re spraying (some metallic paints may require more).
- Base Coat/Clear C oat Paint – As mentioned above, in the early 1980’s, many auto manufacturers switched to a base coat/clear coat paint system. This paint has now become the most popular and common to use when repainting a car. The base coat alone does not have UV resistance and has no sheen when applied. Once you apply the clear coat, the color is sealed in and the paint becomes “shiny”. The nice thing about base coat/clear coat is that it’s more forgiving when finishing the surface for a perfect, glass-like appearance. Wet sanding and using a multi-stage buffing system will remove most imperfections in the paint (bugs, dirt, orange peel, etc.). Base coat/clear coat also gives more protection over a single-stage paint after it’s finished in case of a minor scuff, scratch, etc. as the clear coat acts as an extra barrier over the color.
- Waterborne Paint System – Waterborne paint is quickly becoming the standard in the auto body industry, especially with a majority of the large auto manufacturers using it on new cars. It’s also slowly beginning to trickle into the DIY paint market. Waterborne paint systems use water to suspend the paint or color particles in your paint. The big difference between solvent-based paints and waterborne paints is that waterborne requires airflow to dry versus a chemical reaction that occurs in solvent-based paints. Otherwise, the application of waterborne paints go through a similar process to traditional solvent-based base coat/clear coat systems in that you lay a primer, a sealer, color, then a clear coat and wet sand and buff the paint for the final finish. It’s still relatively new in the DIY market, but keep an eye out for this in the coming years as VOC laws become tighter.
Finishing a Paint Job
If you’ve reached this point, you’re on the home stretch, and this is the most rewarding. In these steps, you’re doing a similar process to what you did when you did your initial bodywork and block sanding of the primer. You’re essentially trying to get the paint and/or clear coat as flat and smooth as possible by taking out any imperfections. Below are the basic steps.
- Removing Dirt and Imperfections – Whether you’re spraying in a fancy high-dollar paint booth or outside, you’ll most likely encounter a paint run or a rouge piece of dirt that will make its way into your clear coat and cause a headache. In this process you take a “nib file” and rub it over the imperfection to get it out of the clear and flatten the paint before you begin sanding the entire vehicle. This will leave the clear coat looking dull, but can be corrected in the next step.
- Color Sanding – This step is pretty simple: you’re using a sanding block, a bucket of soapy water and progressively higher grit sandpaper to smooth out any minor imperfections in the paint including orange-peel (texture in the clear coat), minor runs, drips or sags, etc. If you’ve sprayed a number of coats of clear you can start with more aggressive sandpaper like 600-800 grit to quickly remove the orange peel and major imperfections. Remember to keep the surface wet and check your progress often. Areas that have been properly sanded and flattened out will be dull and low spots will remain glossy. Keep working those areas until they are entirely flat and dull looking. From there, you can work your way up using 800-1000-1200-1500-2000 grit sandpaper until the panel is flat and smooth with no major imperfections. We suggest using a flat sanding block on relatively flat areas or where you need to get up close to bodylines. A flexible sanding block can be used on curved areas to maintain even pressure on the surface.
- Cutting and Buffing Paint – This is the final stage and the most satisfying one. In this stage, you are using a multi-speed rotary buffer to gradually smooth out the finish and bring out the luster in the paint and/or clear coat. Much like color sanding, you’ll be working your way up from an aggressive cutting compound and pad until you reach a final foam pad and buffing compound. The number of steps you take here depends on the final luster you’re seeking. A quick DIY job can be as simple as a wool pad and a cutting compound followed by a final buffing compound with a foam pad, while a professional job will require multiple steps of compounds and pads along the way. You can find a full line of cutting and buffing supplies here.
This article just scratches the surface of the world of painting and auto body work, but hopefully, it gives you a grasp of what is involved in painting a car before you begin. Always remember that the prep work is what makes a paint job really great, so spend the extra time block sanding and making sure everything is as straight as possible before you put color on!