How To Paint A Car
Article by Mark Trotta
Should you paint a car by yourself? On one hand, you can spend $7,500 or more and have someone else paint it. But if you have mechanical ability and a good eye, consider investing $1,500 or so in paint and equipment (that you may use again) and paint your car yourself.
What You'll Need
To achieve a quality paint job, you need the right equipment. This includes a proper size air compressor with water filters, and a quality spray gun. Also necessary is a clean, dust-free environment that people and pets won't be walking through.
One of the keys to a successful paint job is in the surface preparation. After the bodywork is done, there are still a few steps required before you can start to paint your car. These include:
Clean And Prep The Surface
Prime The Surface and Block Sand
More Priming and more Block Sanding
Thoroughly Clean Surface
If you skip over any of these, the paint may not adhere properly, you'll see defects in the finish, and you've wasted time, money, and energy.
Block-Sand The Panels
Once the paint is dry, a few sessions of block-sanding will remove any waves and gets the panels as straight as possible. Start with 240-grit, and when done, switch to 320-grit.
Proper Sanding Techniques
All first-time painters sand off too much paint - it's just the way we learn not to the next time! One way to avoid this is to use guide coats. A guide coat is simply using contrasting colors between each sanding step, which gives a good visual of when you're done sanding.
Re-prime and re-sand any areas that show body filler. Final sand with 400-grit by hand or with a dual-action sander. This will remove any marks left by the block-sanding.
After making sure the body panels are thoroughly clean, mask up any areas you don't want paint on. Use automotive masking tape with paper or plastic sheeting. Take your time with this step, it will help avoid unwanted over-spray.
Before applying masking tape, make sure the surface is clean, dry and dust-free. Wipe the surfaces to be painted with solvents to remove any contaminates on the panels that may cause paint to properly adhere. This reduces the risk of getting "fish eyes" in the paint.
Masking Tape and Paper
Automotive masking tape is different than household masking tape - it's heat resistant for spray booths and heat lamps. It will adhere well but won't leave residue, just a nice crisp line.
Apply the tape without stretching too hard, pressing down as you go. Once applied, press the tape in place with a smooth edge object, like a putty knife or a credit card.
The final step before spraying is to use a high-quality tack cloth (also called a tack rag) to remove any dust that has settled.
If you applied any Bondo or filler, a good sealer should be used before spraying the primer. Some putties will absorb the primer and reducers.
To achieve a strong lasting bond to the metal, apply a self-etching primer over any bare metal. Etching primers are lacquer-based and formulated with a very small amount of acid, which "etches" into untreated bare metal. It also offers corrosion protection, making it ideal for patch repairs such as floors and fender patches.
Self-etching primers are compatible with most primers, including Urethanes. They are also compatible with most enamels. They are not compatible with epoxies.
Many two-part urethane primers are high-build and will hold up better than one-part primers or lacquer primers. You may want to spray as many as four or five coats. Allow the primer to air dry for at least one full day before the next step of block sanding.
Before spraying the final coats, clean all sanding residue off with soap and water, followed by water only. Use a high-pressure air blow gun to dry all panels clean and dry.
Shop: Speedokote Single Stage Urethane Paint Kit
How Much Paint Will I Need?
Depending on the size of your car, you'll probably need a gallon or two of primer, two or three gallons of topcoat, and two gallons of clear coat. It's a good idea to factor in some practice beforehand, and for corrections needed afterward.
Spray Painting Technique
Hold the spray gun about 6-8 inches from the panel. If you stand too close you'll get runs and sags. If you're too far away you won't get a good covering. While spraying, do not stand in one spot and "fan" the gun back and forth. Maintain the same spray gun to car distance while slowly moving.
Start from the top, right to left, then come back the other way, spraying about 50 percent overlap from the last line of paint that you laid down. Several light coats are best, followed by one slightly heavier coat.
Tip: Before spraying on the car, do a couple of test sprays on some cardboard after you fill the paint cup. This is a good way to see if the paint is coming out too heavy or too thin, and adjust accordingly.
Allow The Paint To Dry
After the car is painted, allow the paint to air dry for at least one full day (follow the manufacturer's suggestions). Remove the masking tape and paper carefully. Before wet-sanding, any dirt nibs can be removed with a dirt nib file.
Wet-sanding paint is tedious and messy, but it's necessary step to remove any orange peel from the paint. Fot this, you'll need a bucket of clean water, wet sandpaper. and a couple different sanding blocks.
Harder blocks are best for taking out orange peel quickly. Use a softer block for curved areas. Be careful around the edges not to cut through the clear coat, or you will have to repaint that area.
Most people start with 1000-grit sandpaper, but I've used 800 grit and sometimes 600 grit to knock down heavy runs and orange peel. You just have to careful not to take too much off.
The best way to sand is by hand, but if you're real careful you can use a random orbital polisher. I prefer to take my time and wet sand by hand.
After the 1,000-grit sandpaper, wash the car to get all the sanding grit off, then switch to 1500-grit. You may want to take it a step further and go to 2000-grit. This will make the buffing part faster and easier.
An electric buffer polisher allows you to buff out swirl marks in fresh automotive paint. They also work well to remove spider webs, and polish and apply wax.
Shop: Power Buffer Polisher
The Avid AEP127 is a six-inch dual-action (random orbital) car buffer polisher/waxer. It features variable speed and comes with foam pads for car polishing and waxing. The pads are held in place by the hook and loop system (similar to Velcro) which are easy to put on and take off.
Buffing Out New Paint
After wet-sanding, buff paint in circular motions with an electric buffer, wool pad, and compound.
Be careful not to burn through the paint by holding the buffer in one spot for too long.
Work with approximately two square-feet at a time until the haziness is gone. This is followed by a rubbing compound, either by hand or machine. Final finishing is done with a swirl-mark remover compound.
I use 3M Extra-Cut rubbing compound.
How long should painting your car take? Working part-time, I completed my 1970 Chevelle in about a month from the time the bodywork was done until it was painted and ready to drive out of the garage (I waited another week before starting to wet sand the clear coat).
If this will be your first automotive paint job, be realistic with your expectations. You may get runs, sags, dirt, or dry spots. Fortunately, most of these problems can be corrected with wet-sanding and buffing.
Health and Safety Concerns
The EPA states that the health risks of VOC's in automotive paint include: eye, nose, and throat irritation; headaches, loss of coordination, nausea, damage to liver, kidney, and central nervous system. When working with these chemicals, you must follow all precautions and make sure you use all of the required safety equipment.
Personal Protective Equipment
The chemicals in today's paints are dangerous and can be absorbed through your skin and eyes. A good respirator is essential (remember to change the respirator filters often). Wear disposable nitrile gloves when mixing and spraying paint. A head sock and full body covering are recommended. Always wear eye protection.
Legal and Environmental Concerns
If you live in a residential area, it may be illegal to paint your car at your house. Before you start painting your car in your home garage, check local environmental regulations. The local fire department or auto-body supply store are good places to ask. If it is illegal to do so, an alternative would be finding a spray booth to rent. If neither of these are possible, you can still prepare your car for a body shop. It's a good way to save money.
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