Spray Application For Pros

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When you've got a lot of surface area to paint nothing gets the job done faster than an airless sprayer.

To make sure you get the best results without wasting paint or time keep these recommendations in mind.

Start by considering the type of paint you'll be spraying.

Is it latex, alkyd, epoxy, urethane?

Or maybe it's a coating formulated to deliver a textured finish.

What surface is being painted?

Drywall, masonry, exterior siding?

Consult the coatings product data sheet to ensure the spray tip you select is compatible with the material and the surface you're painting.

Spray pressure is impacted by the length and diameter of the hose you use.

A longer hose will result in a greater pressure drop, a smaller hose diameter will also reduce pressure at the tip and if you're connecting two hoses together always attach the larger diameter hose to the pump first to minimize pressure drop.

While it's not possible to cover every combination, remember that your airless sprayer, the tip and the hose, are part of a system and must be compatible to operate effectively.

So be sure to consult the manufacturer's instructions.

Now let's look at the spray tip, the most critical part of your system.

Typically paints with higher levels of viscosity will require a larger orifice size.

Assuming the size of the orifice doesn't change wider fan widths will result in lower film thickness.

Narrow the fan width to achieve a higher film build.

Likewise, if the width of the fan doesn't change a larger orifice will allow you to apply more material.

Diminish the size of the orifice and you reduce the amount of paint that's applied to the wall.

Film thickness is also impacted by the speed of application.

Faster application speed will reduce the amount of paint being applied to the surface and therefore diminish the film thickness.

Before painting, be sure to purge the system of any residual paint or solvent material that could contaminate the paint and affect the finish appearance.

When you're ready to begin hold the spray gun about 12 inches from the surface and aim it straight at the area you're painting.

Don't just pull the trigger and keep moving up and down or in different directions, spraying continuously the whole time.

You could end up with double the mill thickness every time you change directions.

Aim your spray gun so that the tip overlaps the previous stroke by a third.

Start moving the gun first, then trigger the spray.

This simple technique will ensure that the entire surface is coated evenly.

If you notice the spray pattern has fingers or tails, increase the pressure, until you get even blemish free coverage.

Even with a perfect spraying technique it's often recommended to backroll to ensure a filled block, hide imperfections on the surface or to provide a smooth attractive finish that also satisfies the coatings recommended film thickness.

Mill thickness is a measurement of the thickness of the paint film when applied to the wall.

It's important because paint is formulated to perform best at a specified thickness.

Apply too much paint and the coating may sag.

Too little coating will result in poor hide or insufficient defence against moisture or UV damage.

The coating manufacturer may express the required thickness as wet mill thickness or dry film thickness, which simply refers to the thickness before or after the paint is dried.

Although there are several types of gauges used to measure mill thickness, this common tool has notches spaced at one mill increments.

Hold the gauge at a 90-degree angle to the surface and press firmly, ensuring that both sides contact the substrate.

The number above the last visible notch indicates the mill thickness of the coating.

If you're measuring wet film thickness there will be a trace of paint on the gauge.

Make sure to clean the gauge as soon as you're finished so it'll be accurate the next time you take a reading.

Proper maintenance will help achieve maximum performance from your spray tip.

Make sure your paint is well mixed or boxed.

Maintain clean filters and use the correct filters for your gear.

Remove the tip when you're done and use a soft, bristle brush to clean it.

To get the most life out of your tip, spray at the lowest pressure possible that will completely atomized the paint.

To do that set the pressure control at its lowest setting and slowly increase it until the paint is completely atomized.

This will also help to extend the life of the sprayer’s piston pumps, pacing motor and other wearable parts.

Over time, if you notice that your fan width is lost 25% of its original size it's time to replace the tip.

For example if a tip with a 12-inch fan width has gradually been reduced to 9 inches over time.

That worn tip will spray 40% more paint but cover 25% less area.

You're wasting a lot of time, money and getting a poor paint job.

This illustration shows how the painted surface area is reduced as a 12-inch tip wears down to a 9-inch, 7-inch, and 3.5-inch fan width.

To keep your airless sprayer in top condition keep the pistons well lubricated.

This wet cup is a reservoir that holds throat seal liquid or TSL.

Greco TSL is specifically formulated to prevent paint from drying on the displacement rod.

It's also clear and won’t impact the performance or finish of the coating.

Oil should not be used in place of TSL.

When you're done for the day, flush the pump with a recommended solvent or water followed by paint thinner or a pump saver solution.

This reserves the packing and helps prevent rust inside the pump.

Finally it's important to use electrical cords that are approved by the sprayer’s manufacturer.

Ports that are longer or smaller gauge than recommended can cause the unit to overheat and shorten the life of the sprayer.

While airless sprayer are generally safe it's important to remember a few safety guidelines.

Make sure the work area is well ventilated and that crew members as well as tools, spray equipment and extension cords are properly grounded to eliminate any source of spark or static electricity.

Never run the sprayer if the surrounding area is wet and if it has a gas engine, never operated indoors.

The high-pressure generated by an airless sprayer can cause a potentially dangerous skin injection unless proper precautions are taken.

Stay clear of highly pressurized fluids.

Never remove protective devices like the spray gun tip guard and engage the spray gun trigger safety when you're not spraying.

Use proper pressure relief practices and never feel for leaks with your hand or try to stop leaks with your hand or foot.

If an injection occurs, even something that looks like a small cut go to the emergency room, tell the doctor that it's a fluid injection injury and report the type of material that was being sprayed.

Knowing how to operate and maintain your airless sprayer will ensure that jobs are completed safely and professionally and add years of life to this critical piece of equipment.