Spray Gun Air Cap Selection Guide

Why Air Cap Selection is Important

The Air Cap for your Spray Gun is critical because it will be one of two primary factors that determine the finish quality of your painting as well as the speed at which you can paint. The air cap will also determine how thick of coating you can atomize and spray pattern size. To know best which Air Cap is right consider the following.

What is the Material Being Sprayed?

• Different coatings will spray well with different air cap technologies (air caps are available in conventional, LVMP, and HVLP designs.  Each style cap has its benefits and drawbacks. Additionally, within each category you can use a gun that is fed by suction, gravity, or pressure. To best understand the difference between HVLP, LVMP, and Conventional consider this article which provides an overview.  For a review of the benefits and drawbacks of suction and pressured fed spray guns you can check out this overview. Remember you can use a suction feed air cap on a pressure fed spray gun but you cannot use a pressure feed air cap on a suction fed spray gun.
• The short summary is a pressure fed gun is best for production and/or high viscosity coatings. Gravity fed spray guns are great for smaller batches with light to medium viscosity coatings (like in wood finishing or the auto industry). Suction fed spray guns take the least time to learn and can be a good first spray gun because they allow you to convert them to a pressure fed spray gun which provides versatility (though they will not atomize heavy coatings well)

What is the Fluid Nozzle Size ?

Air caps will come with a variety of CFM ratings. A higher CFM air cap provides a larger ability to atomize and a larger pattern. This means a high CFM air cap is great for high production or heavy viscosity coatings. If you have a large fluid nozzle you will typically want to match it with the highest CFM air cap available for that spray gun to ensure the air cap can keep up with the fluid delivery.  If your fluid nozzle is small you can choose between the air caps based on spray pattern.

What is your product size?

Spray gun air caps from good manufacturers will come with a variety of caps with different pattern sizes. When choosing a paint gun air cap you will want to choose a cap that provides a pattern that is wide but not excessively so essentially you want to have a pattern that will cover the product in the least number of passes but still allow for pattern overlapping during painting.  For example, if your product is 24 inches in diameter you would want to choose an air cap that will allow a pattern of 12 – 14″. This is because you have to overlap each pass so if you use a 14 inch pattern you can overlap a few inches but still cover the product in 2 passes while minimizing over spray. Additionally if your target is small a round spray pattern can be ideal as it will be significantly smaller than the standard air cap spray pattern.

What does the Paint Gun Manufacturer Recommend?

Good spray equipment manufacturers like Binks, Devilbiss, Sata, and Iwata will have product sheets that have information about pattern size as well as air cap recommendations for different coating categories. Consider their suggestion along with the information above to yield optimum results.  If you need further help finding the right air cap for your painting let us know.  

Sample Air Cap Selection from Binks Trophy Spray Gun.