Choosing the right air compressor for painting cars is essential. Here are three factors you need to consider.

1.  CFM

Choose a compressor that can produce a CFM (cubic feet per minute) that meets or exceeds your spray gun’s requirements. Spraying paint with your gun requires a large volume of air being injected into the paint to atomize or break it up. The CFM rating tells you how much air volume your compressor provides.

A conventional spray gun (HV) uses 10 to 15 CFM, while an HVLP spray gun (high volume) may need up to 20 CFM of air to adequately break up the paint so you can achieve a quality finish.

Note: Don’t confuse CFM with PSI (pounds per square inch). PSI is only a measurement of the pressure that an air compressor provides. It’s the CFM measurement that is critical for proper paint gun performance.

2. Air compressor type

The best type of compressor for a paint shop is a two-stage compressor, which provides four CFM of air per horsepower of the compressor. Single-stage  compressors (commonly found at most hardware stores) provide only one CFM per horsepower. Since an HVLP spray gun may require 20 CFM, choose a two-stage compressor with at least five HP to adequately supply air to your spray gun.

Two-stage compressors are available in rotary screw and reciprocating designs.

• Rotary screw compressors require less maintenance than reciprocating ones, but they don’t deliver as much CFM per horsepower.
• Reciprocating compressors are more expensive than rotary screw ones  but last longer and deliver more CFM per horsepower. An added benefit of these compressors is that they do not produce as much heat and are cooled by air at a lower horsepower.

Compressed air will contain some oil and moisture. Either could cause fish eyes or moisture pockets in your paint finish. This can be prevented by adding a two- or three-stage air dryer connected to a pipe that runs through a filter in your shop.  IF you don’t have an air dryer, you can remove fish eyes in your clear coat by adding GLMA-7054 Fish Eye Eliminator to your clear coat.

Another option is to add a refrigerant dryer to your air compressor, which rapidly cools, then re-warms the air as it leaves the compressor.

Using the correct compressor will supply the right air volume to your spray gun to produce a beautiful car paint finish.