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With Chris Curwen & Expert Auto Painter - Dave Gage (Car Cosmetics)

May 15th, 2007 - Issue 03

In this issue:

• How to thoroughly clean your spray gun after each use so that your gun will provide you with a uniform spray pattern every time you use it and we'll also talk about spray gun maneuvering.

A very important point to remember is that spray paint guns need to be consistently cleaned and maintained every time you use them so they will continue to work properly.

Very small air and material passageways can become clogged very easily by bits of dry paint and debris and it can be very difficult to clear such blockages.

You MUST, form the habit of cleaning your spray gun after every single use.

Each spray paint system will have specific cleaning solvents allotted as part of the entire paint system. Make sure you check with an auto body paint and supply store worker to find out the correct cleaning solutions to use with the system that you are using.

Professional body shops use special enclosed cabinets for spray gun cleaning. Solvent is forced through the gun's assembly under pressure while the trigger unit is maintained in an open position.

When you're about to start the process of cleaning your spray paint gun, put on rubber gloves and a respirator. You should always wear rubber gloves and a respirator any time you are handling thinners, reducers, hardeners or any other paint products that contains chemicals.

Personal safety should always be paramount.

If you don't have access to a cleaning cabinet, fill your gun cup partially full with solvent (thinner). Next, swish it around and then empty it. This will remove the majority of the remaining paint product.

Then, refill the cup again using clean solvent and this time spray it through the unit. This will clean out the inner passageways.

You will then want to fill the cup approximately 1/4 full with clean solvent and spray it through the unit once again. Make sure you then clean the cup thoroughly.

Next, spray further clean solvent through the gun head and make sure nothing but perfectly clean solvent comes out, this will tell you that you have gotten everything out.

Once you are sure the interior ports and passageways are clear, run clean, dry air through the unit to remove deposits of solvent.

There are brushes available designed specifically for spray paint gun cleaning, especially for the housing, air caps and other parts.

Under no circumstances use a sharp object to clear a clogged air cap or port. By not following this rule, you can place small scratches on spray gun parts that will interfere with its spraying performance.

To finish on; use a clean cloth dampened with the appropriate solvent, to remove paint drips and splashes from exterior surfaces.

Always hang or place your paint gun in a vertical position for proper storage once you have dried it with a clean cloth.

Spray Paint Gun Maneuvering

Realize that having a good quality spray paint gun and paint are essential to completing a professional looking paint job but they are not everything. The way you apply the paint is equally as important.

You should always hold a paint gun at right angles to the surface being painted from a distance of 6-10 inches. You will need to check what the recommendation for your particular spray paint gun is.

If you can't achieve this by standing then you will have to use step ladders for high up areas or kneel down for lower areas. This will prevent excess paint build-up causing runs and dry spots. Your free hand should be holding the air hose to keep it away from surfaces you are painting.

If you tilt the spray gun toward the surface it will result in a non-uniform fan pattern and don't use the spray gun in an arc or else the paint will be applied in varying thicknesses to the surface; with paint going on wetter and thicker where the nozzle is closer to the surface and drier and thinner where it is farther away.

If the outer layers of thick, wet paint dry before the underlying layers, the solvent evaporating from beneath will leave imperfections in the finish.

At the far end of the arc the paint will be applied too thinly to provide adequate coverage or it may be too dry by the time it hits the surface. The result will be something that resembles overspray rather than a proper coating of paint.

The only time painters would arc the spray gun is on small spot repaints. These spots call for full coverage in the center and less paint around their feathered perimeter as it blends with the existing paint. Practice this technique on a test panel before attempting it on your vehicle.

Automobile roofs, hood and trunk lids lie in the horizontal plane. This means that you should hold the paint gun horizontally when making smooth, even and uniform passes.

Depending on your height and location of some panels, you may have a hard time reaching the middle of some larger panels. You would be well advised to remove the panel in order to be sure you get an even coat.

As shown in 'How to Paint a Car' - Part 1, the silver body parts being painted in the spray booth upon holding racks makes the job for the painter a lot easier.

Referring to the car hood, once the painter has painted up to the middle of the hood he walks around to the other side and continues painting until the hood is finished.

In doing so, there is no chance that by leaning over the panel he will accidentally catch the freshly painted surface with an item of his clothing, thereby leaving blemishes on the surface.

To prevent paint from dripping on the panel being painted, it would be a wise move to apply tape around the top of the cup to hold the lid firmly in place.

Depending on the design of your spray gun and the paint cup, this may not be necessary. The paint cup may attach itself to your gun by screwing it from its base.

If this is the case, tape around where the two meet once the cup is screwed in tightly. This is a good idea even for those spray guns that are advertised as never to drip.

Hold the paint gun so that the nozzle is perpendicular to the surface. This is very important. Do whatever it takes to ensure a right-angle position. Moving from one panel to another in a smooth, steady and even walk will take practice to get it right, so make sure you do indeed practice using your test panel or paper.

Your fan spray should overlap the previous spray by half. The center of the first pass should be directed along the masking line with half of the paint on the masking paper, the other half on the body surface.

The second pass should be directed so that the top of the fan rides along the masking line. Each pass should then overlap the previous one by half, maintaining each pass at the same speed and at 6-10 inches away from the surface.

Start by painting the edges of an area first and then the main surface. This way overspray will help to cover the main area where you can then apply less paint if necessary.

If you apply paint at the appropriate thickness first to the main surface and then paint the edges, the extra paint from the overspray may cause imperfections on the main surface.

If you decided not to practice applying paint onto an old test panel, you may discover runs and flaws when you come to inspect your work. Runs are the result of too much paint being applied to a surface at any one time.

You may be holding the paint gun too close to the surface or fanning the spray too slowly. Whichever mistake you are making, make adjustments to your application until the paint is smooth and even.

As shown several times throughout 'How to Paint a Car' - Part 1, you must remember to use wax and grease remover to remove all surface contaminants before the application of any stage in your paint system.

It doesn't matter if you are painting a small or large area. You must then spray the entire surface with an air hose to dry the surface, making sure that no wax and grease remover or any other moisture is left on the surface.


That's all we have for you this week. Thank you very much for reading. We both hope this issue has been of valued interest to you.

Next week we'll cover Air Compressors.

Happy Painting!

Chris Curwen & Dave Gage
www.LearnAutoPainting.com