What defines a 'conventional' spray gun, and when might I choose one?

Conventional spray guns, also known as air-atomizing guns, use a high volume of air to atomize the paint into a fine spray. While newer technologies like HVLP offer higher transfer efficiency, conventional guns can be preferred for achieving specific finishes, handling thicker materials, or for smaller jobs where speed and ease of setup are paramount. For example, an Astro Pneumatic siphon feed gun might be chosen for its simplicity and ability to spray a wide range of coatings without requiring specialized equipment.

What are the key differences between siphon feed and pressure feed conventional spray guns?

Siphon feed guns, like the Astro Pneumatic AS7SP, draw paint from a cup below the gun using a vacuum created by the airflow. They are generally simpler and more versatile for occasional use. Pressure feed guns, such as the DeVilbiss JGA series, use compressed air to force paint from a separate pressure pot or tank, allowing for higher material flow rates and more consistent spraying, especially with thicker coatings or larger projects. Consider your project size and material viscosity when choosing between these two feed types.

What nozzle size should I select for my conventional spray gun?

Nozzle size is crucial for achieving the desired finish and flow rate with your chosen material. Smaller nozzles (1.2-1.4mm) are often used for finer finishes like automotive clearcoats or touch-up work, as seen in the Astro Pneumatic touch-up gun. Larger nozzles (1.8mm or greater) are better suited for thicker materials like primers, sealers, or industrial coatings. Always refer to the paint manufacturer's recommendations for optimal nozzle size and adjust air pressure accordingly. It's best practice to start with the recommended size and adjust based on your results.

How important is air pressure regulation when using a conventional spray gun?

Precise air pressure regulation is critical for consistent atomization and finish quality with conventional spray guns. Too much pressure can cause excessive overspray and bounce-back, while too little pressure can result in an uneven, orange-peel texture. Use a high-quality regulator and gauge at the gun or air source to maintain the pressure recommended by the paint manufacturer. Experimentation on a test panel is always advised to dial in the optimal settings for your specific gun, material, and technique.

What kind of maintenance is required to keep a conventional spray gun working properly?

Regular cleaning is essential for maintaining a conventional spray gun's performance. Immediately after each use, thoroughly flush the gun with the appropriate solvent, disassembling and cleaning all components, including the nozzle, needle, and air cap. Dried paint can cause clogs and affect the spray pattern. Lubricate moving parts as needed with a gun-specific lubricant. Proper maintenance will extend the life of your spray gun and ensure consistent results. Some guns, like certain Astro Pneumatic models, are designed for easier disassembly and cleaning.

Can I use a conventional spray gun with water-based paints?

Yes, conventional spray guns can be used with water-based paints, but it's important to ensure the gun is compatible and properly cleaned. Water-based paints can corrode certain materials, so look for guns with stainless steel or other corrosion-resistant components in the fluid passages. Thorough cleaning is even more critical with water-based paints, as they tend to dry quickly and can clog the gun if not removed promptly. Always follow the paint manufacturer's recommendations for thinning and spraying water-based products.

What safety precautions should I take when using a conventional spray gun?

Spraying paint with a conventional gun creates airborne particles that can be harmful to your health. Always wear appropriate personal protective equipment (PPE), including a respirator or supplied-air respirator, eye protection, and gloves. Work in a well-ventilated area or use a spray booth to minimize exposure to fumes and overspray. Avoid spraying near open flames or sources of ignition, as many paints and solvents are flammable. Refer to the paint's Material Safety Data Sheet (MSDS) for specific safety recommendations.

How do I adjust the spray pattern on a conventional spray gun?

Conventional spray guns typically have adjustable controls for fan width, fluid flow, and air pressure, allowing you to customize the spray pattern. The fan width control adjusts the horizontal size of the spray pattern. The fluid flow control regulates the amount of paint being dispensed. Adjusting these controls, along with air pressure, lets you adapt the gun to different surfaces, coating types, and application techniques. Practice on a test panel to find the optimal settings for your specific needs. Some guns, like the Astro Pneumatic AS6S, are designed for fine adjustments.