Spray Method of Painting

Spray painting is fast, relatively easy, and provides good coverage in a short amount of time.

With just a bit of practice and patience it also gives professional looking results. As with brush and tip you want to exercise patience. In fact I can quite confidently state (having caused my own worst problems) that your biggest ally in painting will be your patience.

If you've never done it before you will want to practice on something that no one will particularly care about. In other words, wait to paint the car or boat for another time when you are more familiar with the equipment and methods.

First, you should only paint when weather permits. This is assuming, of course, that you do not have a large climate controlled spray booth to do this in.

Your ambient temperatures should be between sixty (60°) and ninety-five (95°) degrees Fahrenhiedt. Or eighteen (18°) to thirty-five (35°) degrees Celcius.

The relative humidity should no more than 70 percent. Contrary to popular opinion this has nothing to do with the paint drying and everything to do with how it looks when dry. Relative humidity above seventy percent will cause the paint to dry "cloudy" from the trapped moisture.

The tools are kind of expensive. You can likely rent a compressor and hose; you might even be able to rent the sprayer, but this is less likely.

• Sandpaper (100 to 400 grit)
• Sandpaper (1000 + grit for wet sanding)
• Tack rag
• Denatured Alcohol

• Thirty gallon (or better) air compressor with regulator
• Fifty feet of hose

• High Velocity Low Pressure (HVLP) Sprayer
• Paint (of course)
• Thinner
• Solent
• Stirrers
• Paint strainer
• Containers
• Gloves
• Eye protection
• Masking Tape

A number of things need to be done to the surface to get the best coating. If there is already a layer of paint you'll want to at least wet-sand.

Wet-sanding, as the name implies, involves water and sandpaper. You'll want a very fine grit of sand paper like 1000 or higher. This paper is specially formulated to be immersed in water. The water holds the particles that have been sanded off of the paint in suspension. Every so often use a wash cloth or clean rag and squeeze water over the surface you are sanding. You should be able to tell when you are getting a nice smooth finish.

If the surface is fresh unpainted FRP you are going to want to use a lower grit sand paper, 400 grit or so, and sand in different directions with the paper attached to a sanding block. Wet-sanding is not advised for an unpainted surface because it won't make any difference and will waste your time. An unpainted surface should be painted with a primer coat first. A good primer provides an excellent bond between the raw material to be painted and the actual finish paint that will be seen.

Once dry the primer coat should be wet-sanded.

Once you've got the surface to be painted properly prepared with sanding you now want to make sure that none of the particles created by the sanding will be trapped in the paint.

First, I recommend blowing the surface clean or using a bench brush to clear away most of the debris. Next, use a clean dry rag and some denatured alcohol to wipe up any remaining dust. Be sure to turn the rag often to present a clean side to the surface to be cleaned.

Next, and for most this step is unnecessary, use distilled water on a fresh clean cloth to wipe away any other debris.

Let the surface dry completely.

Next you will want to apply masking tape to those areas that you don't want paint. I recommend painters masking tape as it has a very straight edge and is easy to distinguish from paint due to it's bright blue color.

Masking tape has a number of properties that make it ideal for painting applications.

• Uses a weak adhesive and is easy to remove
• Has straight edges
• Is stretchy and so can be made to form curves
• Is a good barrier to paint and will not let most paints leach through.

Be sure the tape conforms to all of the curves in the areas to be protected. If larger areas need to be protected you can use sheet plastic (held in place with masking tape) or what's called butcher paper.

As you finish taping an area fold the free end back on itself to create a tab that can be easily lifted away from the job for ready tape removal.

Now that you have your surface prepared mix the paint according the manufacturers recommendations. Be sure to take the weather and humidity into account.

Once you have the paint prepared in the mixing container you will want to strain it into a new clean container.

Use a cone shaped paint strainer and slowly pour the prepared paint through it into the clean container. This will do two things. It will trap any large particles the manufacturer might have missed and knock out any air bubbles that might have formed during mixing.

Now that you have your paint properly mixed load the gun. You want no more than a pint of paint in the "hopper." Chances are good that you won't even use this much.

Set the air regulator to no more than 35 PSI (pounds per square inch) of air pressure. More than this might damage the gun and defeats the idea of the HVLP principlel. After all, you want to shoot the paint on the surface not scatter it all over the shop.

Grasp the hose with your free hand. You want to keep it well away from your work. Position yourself near the object to paint and press halfway down on the trigger to start the air flowing without the paint. Have the gun pointed slightly away from the object you are painting.

Press the trigger fully down. Paint should start flowing. As it does move the gun over the object you are painting at a steady speed, relatively slowly. Keep the gun at the same distance from the object at all times. Eighteen inches to two feet is ideal.

If you have to make repeating passes to apply the paint run the gun slightly beyond the object you are painting. Trying to stop the paint right at the edge will guarantee thin spots. Better to over shoot and get good coverage than create more work for yourself later.

Try to work from the center out. Also, it usually better to get the detail or complex curves painted first and do the larger flat areas last.

Do not over do it. If you don't get good coverage the first time you are just going to have to wait for that coat to dry and get it with the next coat.

It is very easy to apply to much paint and get runs and sags so its better to proceed with caution. No matter what, with the newer paints you are going to have to give it three coats anyway. These paints are very thin.

Paint is self leveling also so any irregularities will likely smooth out as the paint drys.

Watching the video below the painter has a very steady hand, keeps the gun at the same distance from the work at all times, and he virtually floats over the car to get good coverage.

Notice he is also wearing a mask.

Once you've got your first coat on stop!!! Do not attempt to thicken thin areas. Do not attempt to add some shine. It is very easy to apply too much paint and trying to correct sags or runs is much harder than simply applying another coat.

If you are applying another coat, after the prescribed drying time, be sure to wet-sand between coats.

If this is your last coat remove the masking tape now. Remove it carefully by pulling the tape away from the work at a ninety degree angle. Bundle it into a ball as you go along to prevent loose ends from touching the wet paint. Removing the tape before the paint drys insures that you don't pull set paint away from the surface by accident.

Clean your gear and go have a beer. You wont want to touch anything for about twenty-four hours.

Note: Spraying a new layer of paint over a layer from the previous day softens yesterday's underlying layer. So, you want to be very careful after additional coats.

Finally, try to allow your paint to dry for a week before taking the car, boat, or whatever you painted out into the world. Though this isn't always possible, allowing for a full cure will help the coating stand up to the daily abuse of the everyday world far better.

Some paint, notably Interlux^tm BrightSide, has teflon in the mix. This is added to the paint to make caring for the dried product much easier. Since the teflon is designed to "migrate" to the top of the paint as it cures, it is very important that you wet-sand this paint prior to a second or third coat or your additional coats will not adhere.

Do not wet-sand the final coat.

Wet sanding before additional coats is always a good idea regardless of the paint being used.

Sorry about the music. Well, maybe not!

This guy has very good technique. Notice that the gun is always the exact same distance from the car at all times. The painter makes very smooth movements and his hands are the part of his body he is concentrating on. He also overlaps each pass starting each new pass at the "wet-edge" of the last pass.

Though he does not start at the middle and work out he does paint the more complex shapes first. I recommend starting at the middle though. If you are new to this you are likely to get quickly fatigued. This is when mistakes (like dragging the air hose over your work) occur. So start in the middle when you feel fresh and as the odd position starts to wear on you there's less likelihood that you'll forget about the air-hose.

He also paints beyond the body of the car to insure consistent coverage to the very edges. You can see this toward the end; the paper of the windshield is almost completely covered with paint. This is also good technique. Painting beyond the edge may seem like a waste of paint, but it insures you get good coverage all the way to the edges of your work area.

The last few minutes of the video show off the quality of the work.

Cleanup is pretty straightforward. This is the only time to use acetone if you use it it all. Thinner works well too. Denatured alcohol is not going to do the job.

First fill the reservoir with solvent and let the gun sit, upright, for fifteen to twenty minutes. At the end of this time swish the solvent around and pour out the contents.

Using a small clean container, like a cottage cheese or margarine tub, disassemble your sprayer into the tub. You only want to remove the screw off tip. Place these parts in the tub pour solvent over them. Using an old toothbrush and gloved hands gently rub off any paint.

Finally reassemble the sprayer, add about a 1/2 cup of solvent to the reservoir and spray the solvent through the gun. Do this far away from your paint job.

Do not rinse with water. Hang the sprayer somewhere it can air dry. Once dry seal it in a clean dry plastic bag to prevent corrosion.