Coating Application Methods and Equipment
Application methods include airless spray, conventional air spray, plural-component spray, electrostatic spray, brush, roller, and trowel. Airless spray is common for high-build coatings: fluid is pressurized and forced through a small orifice, so tip size and fan angle control output and pattern. Conventional air spray uses compressed air to atomize; it gives finer atomization but lower transfer efficiency. Plural-component equipment meters and mixes two components at the gun, requiring ratio verification, solvent flushing, and pot-life awareness. Brush and roller are not obsolete-they are required for stripe coats, edges, welds, and areas unreachable by spray.
Key variables are tip orifice, fan width, fluid pressure, gun distance, travel speed, overlap, and gun angle. Hold the gun 12–18 inches from the surface, perpendicular, and overlap each pass about 50%. Trigger before the edge and release after it to avoid heavy bands. Traps: raising pressure to fix a worn tip or clogged filter; using too small a tip and over-atomizing; spraying too far and creating dry spray; moving too slowly and causing sags; and forgetting that pressure drop in long hoses changes the pattern.
Worked rule: a 10-inch fan with 50% overlap advances 5 inches per pass. If the fan narrows or becomes heavy on one side, stop and inspect the tip, filter, and fluid pressure before continuing. Verify wet-film thickness during application rather than discovering a low DFT after cure.