Topside Painting > Painting Equipment > Spray Equipment Basics

Alyssa Copeland
  • Updated
Up close of paint spray gun tip

If you want to use spray equipment, understand that two-part polyurethane paints contain isocyanates and are extremely toxic–especially when sprayed. It’s best to leave the spraying of two-part polyurethanes to the professionals because the protocols for masking, air handling/filters, and respiratory protection are much more serious. The information provided here is intended to help you learn more about various types of spray equipment, not to teach you how to use a certain type of spray gun.

If you’re applying a one-part polyurethane by spraying, aside from good ventilation, make sure you have personal protective gear that includes a hooded paint suit, vapor respirator with proper cartridges (not a dust mask), gloves, and goggles. Also, check that you have the correct spray tip for your spray gun and your type of topside paint. For example, certain types of spray equipment and larger spray tip sizes are better for applying topside paints with a higher solids content. Both the topside primer and the topside paint can be applied using the spray method.

There are many types of spray guns available, but we’ll describe the ones most often used by do-it-yourselfers: conventional air guns, HVLP (high volume, low pressure) guns, and air-assisted airless spray equipment. Below is a brief overview. It’s important to take more time to learn all you can about the spray equipment you plan to use to ensure it can do what you want it to do.

Spray Gun Types

Conventional Spray

Uses compressed air to operate at a constant, high pressure to atomize the paint. Produces extremely fine particles.
Creates a smooth finish and is relatively inexpensive compared to HVLP and air-assisted airless sprayers.
Because the target surface is bombarded with a high-pressure blast of atomized paint, only about 30% of the paint actually reaches the surface, the rest goes into the atmosphere. That’s a lot of wasted paint and money, and a serious environmental hazard.

HVLP (High Volume, Low Pressure)

Depending on the HVLP system, uses either an air compressor or an air turbine to apply the atomized paint in a higher volume, but at a much lower pressure.
Creates a fine-quality, smooth finish. Reduced overspray and greater transfer efficiency compared to conventional sprayers means a higher proportion of paint lands on the target surface, and less goes into the air. Decreases the amount of wasted paint and produces less air pollution.

Turbine powered HVLP offers several advantages over compressed air powered HVLP: it achieves proper atomization using half the air pressure, it requires less energy to operate and has greater transfer efficiency, triggering is easier because of the constant air flow through the gun, and reduced overspray and fogging. The initial cost for types of HVLP systems is about the same.
Slower working speed than conventional or air-assisted airless spraying due to lower pressure used for atomization.

AAA (Air-Assisted Airless)

Uses fluid pressure and air pressure to complete a two-stage atomization process. An airless pump provides the fluid pressure to feed the paint to the spray tip; an air compressor introduces compressed air into the spray tip to increase the fineness of atomization.
Softer spray atomization and greater transfer efficiency means a high-quality finish, and the job gets done more quickly.

Ability to spray into recessed areas and cavities without excessive paint bounce-back means less mess.

This method has lower overspray levels comparable to HVLP, and allows continuous spraying of large surfaces.

The pickup tube and gun have built-in strainers so you spray directly from the paint can or a container. EPA approved.
Most complicated and expensive system to use. Requires use of a small compressor and a pump.

Spray Tip Basics

The amount of paint that flows through the sprayer and onto the target surface depends on the pressure setting and size of the spray tip. Spray tips are rated according to orifice size, and vary by manufacturer.

  • Choose a spray tip of a size that’s appropriate for the job you’re doing, and the type of paint you’re using. For example, lighter coatings are sprayed with the smaller tip sizes, and heavier coatings, such as high-solids primer or topside paint, require a larger spray tip size.
  • Make sure your spray equipment can handle the tip size you need.
  • Some paint manufacturers include spray equipment specifications, gun types, and spray tip sizes in their product data sheets. Contact the paint manufacturer if you have questions or need recommendations.

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