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HOW TO SET UP AN AIR COMPRESSOR

FOR SPRAY GUNS & PAINTING


Is there such a thing as the perfect paintjob? That’s the big question for DIYers and professionals alike any time it comes to adding a lick of paint to the walls of the house, the garden fence or when spray painting a car. If you’re yet to ditch the brush or roller and paint tin, the first, and rather big, step on that journey is to invest in an air spray gun.

If you’re not already familiar, spray painting guarantees a much more controlled and even finish on your work than any hand-applied brush/roller job, but just investing in any old spray paint kit and assuming it will immediately produce optimal results won’t get you too far. To avoid improper application and the dreaded “orange peel” effect, you need the right kit, and that means getting a spray paint compressor that meets the specifications your spray gun setup requires.

Our guide will walk you through everything you need to know regarding paint compressors and the technical delivery elements required. Then, once you know what you’re doing, we’ll tell you about a few of the best spray gun and compressor kits available on the SGS website, so you can make a masterpiece of any paint job you take on going forward.


What is a gun compressor?

When we talk about an air compressor for painting, we’re not actually talking about a specific type of compressor exclusive to spray painting function, but rather a suitable air compressor for spray gun use.

When it comes to spray painting, air compressors are commonly used to provide the necessary air pressure to atomize and propel paint particles from the spray gun onto the surface being painted. The air compressor takes in ambient air and compresses it, storing it in a tank at a specific pressure. When the spray gun trigger is pulled, the compressed air is released in a controlled manner, mixing with the paint to form a fine spray.

Air compressors used for spray painting applications can vary in size, capacity, and specifications. The appropriate compressor for spray painting depends on factors such as the type of spray gun being used, the desired air pressure, the volume of air required, and the specific painting project.

Most air paint spray guns use a “high volume, low pressure” (HVLP) delivery mechanism, thus it’s important to find a spray paint compressor that delivers the required pressure and volume of air in order to create a consistent paint flow that will give you a perfect finish.

It's important to select an air compressor that can provide the necessary air pressure and volume to meet the requirements of the spray gun and the paint being used. Manufacturers of spray guns typically provide guidelines and recommendations for the minimum air pressure and airflow needed to achieve optimal results.


What is HVLP?

HVLP stands for High Volume Low Pressure. It is a type of spray painting system that is designed to deliver paint at a high volume while operating at a lower air pressure compared to conventional spray guns. HVLP systems are commonly used in various industries, including automotive refinishing, woodworking, and general painting applications.

The key features of an HVLP system are:

High Volume: HVLP systems are designed to deliver a higher volume of paint compared to traditional spray guns. This allows for faster and more efficient coverage of surfaces, reducing the number of paint coats required.

Low Pressure: HVLP systems operate at a lower air pressure compared to conventional spray guns. The lower pressure helps to minimize overspray and reduce paint waste. It also contributes to a softer and more controlled spray pattern, resulting in a smoother finish.

Compliance with Regulations: HVLP systems are often used as a solution to meet environmental regulations and reduce air pollution. By operating at lower pressures, HVLP systems can help minimize the release of harmful overspray into the air.

Improved Transfer Efficiency: HVLP systems are known for their higher transfer efficiency, which refers to the percentage of paint that actually adheres to the surface being painted. With HVLP, a larger proportion of the paint is transferred onto the surface, reducing waste and improving overall paint utilization.

Suitable for Water-Based and Solvent-Based Paints:HVLP systems are compatible with a wide range of paint types, including both water-based and solvent-based paints. This versatility makes HVLP a popular choice in various painting applications.

It's worth noting that HVLP systems typically require a larger air compressor compared to conventional spray guns due to the higher volume of air needed. Additionally, some HVLP systems may require specific air caps, nozzles, or needles to achieve optimal performance.

Overall, HVLP systems offer several advantages in terms of efficiency, reduced overspray, and compliance with environmental regulations, making them a popular choice for many professional painters and DIY enthusiasts.


What are the key air compressor requirements for spray painting?

There some key measurements to consider when compressed air spray painting.

Air Pressure

Air pressure is a critical factor in spray painting. It refers to the force with which the compressed air propels the paint out of the spray gun. Air pressure is typically measured in pounds per square inch (psi) or bar. The appropriate air pressure will depend on factors such as the type of paint, the viscosity of the paint, the desired finish, and the specific spray gun being used. Following the manufacturer's recommendations for the paint and spray gun is crucial for optimal results.

Fluid Flow Rate

The fluid flow rate, also known as the material delivery rate or paint volume, refers to the amount of paint being delivered from the spray gun per unit of time. It is commonly measured in fluid ounces per minute (oz/min) or milliliters per minute (ml/min). Adjusting the fluid flow rate allows for control over the amount of paint applied to the surface. The appropriate flow rate will depend on factors such as the size of the project, the type of surface, and the desired coverage.

Nozzle Size

The nozzle size determines the size of the spray pattern and the shape of the paint particles as they are ejected from the spray gun. Nozzle sizes are typically measured in thousandths of an inch (e.g., 1.2 mm). Different nozzle sizes produce different spray patterns, ranging from narrow to wide. Selecting the appropriate nozzle size depends on factors such as the type of paint, the surface being painted, and the desired coverage and finish.

Distance from Surface

The distance between the spray gun and the surface being painted is a crucial measurement to consider. It affects the spray pattern, the paint coverage, and the overall finish. Maintaining a consistent distance is important for achieving uniform results. The recommended distance will vary depending on the specific spray gun and the paint being used. Typically, a distance of 6 to 8 inches (15 to 20 cm) from the surface is a good starting point, but adjustments may be necessary based on the specific requirements of the project.

By paying attention to these key measurements—air pressure, fluid flow rate, nozzle size, and distance from the surface—you can achieve greater control over your compressed air spray painting process and achieve the desired results. It is also vital to consult the manufacturer's guidelines and recommendations for the specific equipment and materials you are using.


How much CFM do I need for spray painting?

The required CFM (cubic feet per minute) for spray painting depends on several factors, including the type of spray gun being used, the size of the nozzle, the desired air pressure, and the specific painting project. The CFM requirement can vary significantly depending on these factors.

To determine the CFM needed for spray painting, you should consult the manufacturer's specifications and recommendations for your specific spray gun. Spray gun manufacturers typically provide guidelines indicating the minimum CFM requirement for optimal performance.

As a general guideline, most gravity-feed spray guns used for automotive or general-purpose painting typically require around 4-9 CFM. HVLP (High Volume Low Pressure) spray guns, which are commonly used for fine finishing and reducing overspray, typically require a higher CFM, ranging from 8-12 CFM or more.

It's important to note that the CFM requirement stated by the manufacturer is typically based on a specific air pressure setting. If you plan to use a different air pressure than what is recommended, the CFM requirement may change.

When selecting an air compressor for spray painting, it is advisable to choose a compressor with a CFM rating that exceeds the requirements of your spray gun. This allows for sufficient airflow to the spray gun, ensuring consistent performance and avoiding potential issues such as inadequate atomization or pulsating spray patterns.

Additionally, consider the capacity of the air compressor's tank. A larger tank size allows for a more continuous supply of compressed air and can help meet the temporary surge CFM demands during spraying, especially for larger painting projects.

In summary, the required CFM for spray painting depends on the specific spray gun, nozzle size, air pressure, and project requirements. Consult the manufacturer's specifications and recommendations for your spray gun, and select an air compressor with a CFM rating that meets or exceeds those requirements for optimal performance.


What is the best air pressure for spray painting?

  • Manufacturer's Recommendations: Always consult the manufacturer's instructions and recommendations for the specific paint and spray gun you are using. They often provide guidelines for the optimal air pressure range.
  • HVLP Spray Guns: HVLP (High Volume Low Pressure) spray guns are commonly used for finer finishes and reducing overspray. For most HVLP spray guns, the recommended air pressure typically ranges from 20 to 30 PSI (pounds per square inch).
  • Conventional Spray Guns: Conventional spray guns, which operate at higher pressures, usually require higher air pressure settings. The recommended air pressure for conventional spray guns can range from 40 to 60 PSI.
  • Test and Adjust: It's essential to perform test sprays on a scrap surface or test panel to determine the ideal air pressure for your specific painting project. Start with a lower pressure setting and gradually increase it until you achieve the desired spray pattern, atomization, and paint coverage.
  • Material Viscosity: The viscosity or thickness of the paint can also influence the optimal air pressure. Thicker paints may require higher air pressure to atomize properly, while thinner paints may require lower air pressure.
  • Surface and Technique: The type of surface being painted and the desired technique (e.g., fine finish, full coverage, textured effect) can also impact the ideal air pressure. Experimentation and practice on similar surfaces can help determine the best air pressure for your specific application.

Remember to make adjustments to the air pressure in small increments and observe the resulting spray pattern, paint flow, and finish. It's important to find the balance that provides good atomization, even coverage, and minimizes overspray.

Ultimately, the best air pressure for spray painting is a result of finding the setting that achieves the desired finish and meets the specific requirements of the paint, spray gun, and project at hand.


How to spray paint with an air compressor

  1. Put on your safety gear: respirator or mask, goggles, and gloves.
  2. Connect your air spray gun to the air compressor using a hose and necessary attachments (such as a filter, regulator, and quick disconnect fittings).
  3. Ensure that your air compressor is delivering adequate CFM (cubic feet per minute) as required by your spray gun.
  4. Mix your paint or primer and solvent according to the recommended ratios provided by the manufacturer.
  5. Perform a test spray on a piece of cardboard to ensure that the compressed air spray is delivering a consistent paint flow. You can adjust the spray pattern on most HVLP spray guns using a knob located on the side of the gun.
  6. Apply an even coat of paint to your chosen surface, holding the spray gun at a consistent distance and moving it in a smooth, sweeping motion. Start and stop spraying before and after the surface to prevent uneven application.
  7. If necessary, wait for the first coat to dry (typically 12-24 hours) before applying a second coat for additional coverage or desired finish.

Air spray gun and paint compressor checklist

As we’ve already established, ensuring you’ve got the adequate CFM and volume in your compressor tank to do the job consistently is essential. However, despite all your best efforts and preparations, you might find that you’re still facing problems with air pressure.

If you are struggling to get the results you’re looking for, there’s a checklist of things to go over to ensure you’re getting optimal performance from your spray gun and air line setup.

Air Spray Gun

  • Check that the spray gun is clean and free from any debris or paint residue.
  • Ensure that all the components of the spray gun, such as the nozzle, needle, and air cap, are in good condition and properly assembled.
  • Verify that the spray gun has the appropriate nozzle size for the type of paint you will be using.
  • Check for any leaks or damage in the spray gun body or connections.
  • Make sure the spray gun is properly lubricated if required by the manufacturer.

Paint Air Compressor

  • Ensure that the compressor is in good working condition and properly maintained.
  • Check the compressor's air filter and clean or replace it if necessary to prevent contamination.
  • Verify that the compressor has the necessary CFM (cubic feet per minute) output to meet the requirements of your spray gun.
  • Check the compressor's pressure regulator and ensure it is functioning correctly.
  • Inspect the compressor's hoses and connections for any leaks, damage, or signs of wear.
  • Make sure the compressor is properly grounded for safety.

Air Supply

  • Ensure that the air supply for the compressor is clean and free from moisture or oil contamination.
  • If needed, install a moisture filter or air dryer in the air supply line to prevent water or condensation from reaching the spray gun.
  • Check the pressure settings on the compressor and adjust them to the recommended range for your spray gun.

Safety Precautions

  • Wear appropriate safety gear, such as a respirator or mask, goggles, and gloves, to protect yourself from paint fumes, overspray, and chemicals.
  • Make sure you are working in a well-ventilated area or use additional ventilation equipment if necessary.
  • Follow proper safety procedures and guidelines provided by the spray gun and compressor manufacturers.

By going through this checklist and ensuring that both your air spray gun and paint compressor are in good condition and properly set up, you can have a smoother and more efficient painting experience.

Spray Gun Kits


When it comes to spray gun kits, there are several options available based on your specific needs and preferences. Here are a few recommendations for spray gun kits:

Still need help? Get in touch with our in-house experts for buying advice and bespoke care, regardless of the application. Call SGS on 01332 576 850 or fill out our contact form today.

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