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  1. #1
    Administrator Cebby's Avatar
    Join Date
    Aug 2005
    Pittsburgh, PA

    Nice tech article from Eastwood on Painting cars

    I found this on Eastwood's site


    If you are restoring a vehicle, a milestone in the restoration process is when you have the vehicle painted. At this stage, although still far from finished, the project really starts to take shape. Depending on your skill level and ambition, you may wish to tackle the paint job. If you have never painted before, the idea of painting your vehicle may seem like a fun project, or it may seem overwhelming. Although there are proper techniques to spraying, nothing is out of the scope of a hobbyist that is willing to practice and learn. To get you started, Eastwood offers books, videos, paint guns, paints, technical advice, and all of the supplies you need to paint your vehicle. When you see your vehicle freshly painted, the sense of accomplishment is the greatest reward.

    A large part of a successful paint job is directly related to the preparation efforts. Painting a vehicle is a tedious process that involves a lot of preparation. If you do not properly prepare the vehicle for paint, you will see defects in the finish and you may experience adhesion issues. In terms of preparation, we are referring to: rust repair, damage repair, bodywork, block sanding, using the correct products, keeping the surface clean, properly sanding everything, etc. If you are willing to put in the time and work, the end results can make it worth all your effort.

    Everyone has different reasons for wanting to paint their car - maybe you like to be able to say you did "all" of the work yourself, maybe you can not afford to have it painted, maybe you want to learn something new, maybe you want to be certain of the work that is going into the vehicle before and during paint....and the list goes on. Regardless of your reasons, there are certain things that need to be considered for a successful paint job.

    To get started, you need to develop a game plan. The key to a successful paint job is planning your steps, taking your time, and properly prepping the surface. If you are in a hurry, DO NOT attempt to paint your car. If you cut corners prepping the vehicle for paint, this will be seen in the final finish or shortly down the road. To properly paint a vehicle, there is a lot more involved than spraying paint onto the vehicle. When developing your game plan, here are several things to consider.

    Do you have a place to prep and paint the vehicle?

    Do you have (or are you willing to purchase) the needed tools to paint a vehicle?

    Will the vehicle be stripped to bare metal or are you going to paint over the existing finish?

    Are you painting the complete vehicle (door jambs, trunk area, underhood, etc) or only the outside?

    What type of paint do you plan on using? - Acrylic Enamel, Urethane, Acrylic Lacquer, Base coat/Clear coat, Water-based, etc.

    What brand of paint system are you going to use?

    If you are considering the idea of painting your vehicle, first think of where you are going to prep and spray it. Do you have a dry place to store the vehicle while you are prepping it? Ideally, you will want to be spraying in a clean, dirt-free, temperature controlled environment. Are you going to rent a spray booth, paint in your garage, or paint in your driveway? Is it legal to spray a vehicle where you plan to paint? All of these factors must be considered before you think about picking up a paint gun. Tip - If it is illegal for you to paint your vehicle in the area you live, you can still strip it down and prep it for the body shop. This is a good way to save money.

    Speaking of paint guns, you will need the proper equipment to paint a vehicle. At a bare minimum, you will need a paint gun, an air compressor that can meet the demands of your paint gun, and a moisture separator. The moisture separator will ensure that you have a dry air supply. Moisture in your air supply is an easy way to ruin a paint job. Another option is a turbine paint system, such as the Accuspray. These systems do not require an air compressor and turbine systems ensure that you have a dry air supply.

    In addition to the spraying equipment, there is safety equipment that you will need. You will need a painter's suit, an approved respirator, goggles, and disposable nitrile gloves are a good idea. The chemicals in today's paints are dangerous and can be absorbed through your skin and eyes. When working with these chemicals, you must follow all precautions and make sure you use all of the required safety equipment.

    There are two general paint gun designs: gravity feed and siphon feed. Gravity feed guns have the cup mounted on top of the gun and use gravity (and air pressure) to feed the paint into the gun. Siphon feed guns have the cup mounted under the gun and use a pick-up tube to deliver the paint to the gun.

    In addition to gravity feed and siphon feed designs, paint guns are commonly known as either hvlp (high volume low pressure) or conventional. Hvlp paint guns pass a high volume of paint through the gun's nozzle at a lower pressure (as low as 10 psi at the air cap). Conventional paint guns require high pressure (60 psi or more) to spray the paint. Hvlp paint guns generally have higher transfer efficiencies, meaning that they put more material on the item you are spraying. This results in less overspray and less wasted material. Some areas require that you paint with an hvlp paint gun or a compliant non-hvlp paint gun.

    We recommend that you use a gravity-feed hvlp paint gun. With a siphon-feed gun, there is always a little material left in the bottom of the cup that doesn't get sprayed. The gravity-feed design allows you to spray the full cup of material. Also, you should consider using cup liners or the 3M PPS system. Both of these items will allow you to spray at different angles, even upside-down. Eastwood offers a variety of paint guns from DeVilbiss, Binks, Sata, Sharpe, and more.

    Depending on the type of paint you plan to spray, you may need additional tips & nozzle caps for the gun. Some paint guns come with tips and nozzle caps to spray heavy primers, while others are better suited for spraying lighter-bodied paints and clears. For lacquers, enamels, urethanes, base coats, and clear coats you will want a spray gun with a 1.3 - 1.5mm fluid tip. For spraying water-based automotive paints, such as Auto Air, you will want a spray gun with a 1.0mm fluid tip. For heavy paints and primers, a spray gun with a 1.8 - 2.2mm fluid tip is ideal.

    When deciding to paint your vehicle, how far do you plan on taking the vehicle apart? Are you going to remove the hood, trunk, doors, glass, etc, or are you going to tape it up and paint while it is together? Taking everything off allows you to make sure there is no hidden damage and it allows you to get paint into all of the nooks and crannies. However, you will have to deal with gapping the panels, reinstalling glass, replacing seals, etc.

    If you decide to paint the vehicle while it is still together, remove as many of the small items as you can - antennae, door handles, lights, locks, wipers, etc. Nothing looks worse than a nice paint job that has overspray all over items that shouldn't have been painted. If you are leaving items on the car that are not going to be painted, be sure to use a quality automotive masking tape and masking paper....newspaper does not cut it. Newspaper is porous and can allow paint to get through to the surface below. Tip - To get paint under seals that are installed, an old trick is to take some nylon clothesline or coated wire and to put it under the seal and then mask off the seal. This will lift the seal enough to allow paint to spray between the seal and the body of the vehicle.

    Do you plan on stripping the vehicle to bare metal or painting over the existing finish? Stripping the vehicle to bare metal allows you to see what is hiding under the paint - rust, body filler, shoddy repairs, and other damage. You'd be surprised what has been found under existing layers of paint. Stripping the vehicle to bare metal also allows you to know exactly what products are being used. If you paint over an existing finish (this is perfectly acceptable for some applications), you never really know what is hiding under the surface. Also, if this finish was not properly prepped for, your new coating may flake off due to the existing finish flaking off. If you do not know the history of the finish on the vehicle, it is generally a better idea to strip it to bare metal and start fresh. There is nothing worse than having a new paint job flake off or have rust start popping out due to shoddy repairs that were made under an existing finish.

    When painting over an existing finish, the finish must be in good shape. Faded finishes are okay, but it should not be peeling, cracked, or otherwise damaged. If the vehicle has been repainted, it is recommended that you strip the vehicle down and start from bare metal. If you do decide to paint over the existing finish, wash the vehicle and then use a quality wax and grease remover on the surface. This will remove any wax that could cause adhesion problems. Now, you will want to wet sand the surface with 320-400 grit sandpaper. This will roughen the surface and allow your new finish to adhere. If there are any chips, dings, or scratches, repair them with a catalyzed glazing putty. Once you make these repairs, you should seal the entire vehicle with a quality sealer primer.

    Generally, it is recommended that you stick with one brand's paint system throughout the entire painting process. However, there have been many successful paint jobs that have mixed products. If you decide to mix primers and topcoats, from different manufactures, we recommend that you test for compatibility before you start spraying on your project. Tip - Eastwood's new line of primers and clearcoats are high qulatilty products that work well with most paint systems. These products work especially well with Auto Air paints. For repairing wavy panels, EverCoat Slick Sand is also a versatile, high-build, sprayable, polyester primer that can be used with most types of top-coats. It can be applied over bare metal or prepped painted surfaces.

    If you decide to strip the vehicle to bare metal, there are several options - chemical paint strippers, chemical dipping, media blasting, and mechanical stripping. Each method has pros and cons.

    Chemical paint strippers can quickly remove multiple layers of paint. Chemical strippers are available in aerosol and brush on applications, and in liquid and gel forms. Usually, multiple applications are required to fully strip the panel to bare metal. It is advisable to avoid seams, as stripper may seep out after you have painted your vehicle and lift your fresh paint, if all of the stripper was not removed. Chemical stripping can be messy, but it is effective at removing multiple layers of paint. Be sure to read all warning labels, follow directions, and use appropriate safety equipment.

    Chemical dipping is done by professionals, this is the process of dipping the vehicle. This method is very effective and removes all paint, body fillers, seam sealers, and rust. It also strips the inside of panels. If the chemical is not fully cleaned from the vehicle, it can seep out and lift the new paint. Also, this method will clean the back sides of panels and other areas that are hard to access. If you can not treat the inside of panels, they can start rusting from the inside.

    Media blasting is a method of stripping paint, rust, and body fillers by using abrasive blasting equipment. With this method, media (sand, poly abrasive, walnut shells, baking soda, slag, etc) is shot at the vehicle and it abrades the surface to remove the coatings. Different types of media are available for stripping coatings and rust. Depending on the media being used, care must be taken to avoid warping large flat panels. Also, abrasive can get into cracks and crevices. If this is not thoroughly cleaned, it could blow out and end up in the paint when spraying the vehicle. Media blasting can be used to quickly strip large areas of paint and rust.

    Media blasting can be done at home with a siphon blaster or a pressure blaster. Pressure blasters are quicker than siphon blasters. Eastwood sells several models to suit your needs. Be sure to use appropriate safety equipment, including a NIOSH approved respirator and a blast hood.

    Mechanical stripping is another method of paint removal. It can be done by hand sanding with sand paper, or by using pneumatic or electric grinders and sanders. Sand paper, cleaning discs, stripping discs, and wire wheels are common methods. This process is effective, but it can take longer than other means of paint stripping.

    Now you need to decide on the paint type and paint brand. Most paint manufacture's recommend that you use their paint systems - cleaners, primers, paints, and clear coats. This is to ensure that there are not any adverse reactions between different products. There are a large variety of paints available that can be used - acrylic lacquers, acrylic enamels, urethanes, base coat/clear coat, and water-based are quite popular today with automotive hobbyists. Eastwood carries House of Kolor custom paints and Auto Air water-based paints.

    For typical paint jobs, here is an example of the steps for something that has been stripped to bare metal:

    Wipe down surface with paint prep

    Epoxy primer - epoxy primers offer superior protection of the bare metal.

    Bodywork done on top of the epoxy primed surface

    Sealer primer

    3-4 coats of base coat

    3-5 coats of clear coat

    (This is an example of the steps that products are commonly applied. Paint manufacturer's recommended products and application order may vary. Paint manufacturer's instructions should be followed.)

    Depending on the purpose of your project, you might select different types of paint. With restoration projects, many hobbyists opt for acrylic lacquer or acrylic enamel to replicate the factory finish. If you are looking for durability, urethanes, base coat/clear coat finishes and water-based finishes are great.

    Before you start to spray, be sure to read the paint mixing instructions and paint gun instructions. Be sure that your paint gun is set-up to spray the type of finish you are using. If you have never painted before (or even if you have painted before), you may want to look into our Paintucation videos. These videos show you how to avoid common mistakes and give a wealth of information. Before spraying your project, practice, practice, practice. Spraying a fender is a lot different from spraying a whole vehicle. Spray your wheel barrow, lawn tractor, trash can, or go to a salvage yard and pick up some extra fenders, hoods, or doors. This will allow you to get the feel of spraying, and also allow you to practice with different air pressures and fan patterns. This is also a good way to learn the products you are spraying.

    When setting up your paint gun, hold the gun 6 inches from the surface and try to get a fan pattern that is approximately 6 inches for spraying automobiles. If you are spraying smaller objects, a 4 inch pattern is usually ideal. We recommend that you practice with different fan patterns before you begin spraying your project.

    When spraying, be sure to keep the gun parallel to the surface you are spraying. If you are spraying a solid or metallic color, you should use a 50% overlap on each pass. For candies and pearls, you usually want to use a 75% overlap. When spraying, you should walk with the gun and keep your wrist firm. If you move your wrist, this will vary the gun's distance from the surface you are spraying, resulting in uneven coverage. A large part of spraying is developing a feel. The more you practice, the better you will become. There is a fine line between laying the paint on flat and texture-free, and running it off the panel. To get this feel, you must practice and become acclimated to your spray equipment and the products you are spraying.

    Be realistic with your expectations of your first paint job. It probably won't be perfect. There might be dry spots, runs, dirt, and/or bugs. Take your time and remember that many of these problems can be corrected with color sanding and buffing. Use each paint job as a learning experience. With practice, the right equipment, the right products, and Eastwood's expert advice, you will be able to produce a paint job that you are proud of.

  2. #2
    Contributing Member MXtras's Avatar
    Join Date
    Nov 2005
    Somewhere in Virginia

    Re: Nice tech article from Eastwood on Painting cars

    Pretty nice article - lots of good, fundamental information.

    One thing I can add from experience - Actually I have many, many things to add but the biggest thing pertains to media blasting. One major thing that was not mentioned is the fact that media blasting creates distortion on the panels. It would be my last choice to prep a vehicle for paint because of the mess it makes and because of the subtle panel distortion. The cons are not worth the pros, in my opinion.

    If it wasn't for the last minute I wouldn't get anything done

  3. #3
    Contributing Member MXtras's Avatar
    Join Date
    Nov 2005
    Somewhere in Virginia

    Re: Nice tech article from Eastwood on Painting cars

    Another issue that I learned the hard way.

    Use flourescent lighting - NOT halogen. The halogen sounds like a good idea to illuminate the lower portions of the vehicle but all it does is illuminate the overspray. I once set up and painted a car using a mixture of flourescent and halogen lights - the halogens were aimed to the lower sections as I was painting a dark color and never seemed to have enough light down low. All was fine through the dark base coat, but as soon as I pulled the trigger on the clear - I couldn't see a thing but the overspray. It made it very difficult to see and because of the arangement, I was kinda forced to continue rather than turning them off as this was a make-shift paint booth and the electrical connections and the lamps were outside the booth perimeter. I managed through it, but it was frustrating.

    Long story short - stick to flourescent or incadescent lights for spraying a vehicle. If the car looks good under flourescents, it's going to look awesome outside. Flourescents show EVERYTHING.

    If it wasn't for the last minute I wouldn't get anything done

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