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Prepare a controlled test
Orange peel becomes unacceptable when the wet film can no longer level before solvent release fixes the surface texture. The pressure threshold is not a single universal number. It depends on viscosity, nozzle size, fluid output, reducer speed, gun distance, booth temperature, and the energy available to break the coating into uniform droplets.
Prepare a test panel with the same primer, sealer, and orientation as the repair. Mix enough coating for all test sections so viscosity remains constant. Divide the panel into five zones and label each zone with the planned dynamic pressure. Keep fan width, fluid-control position, distance, overlap, and travel speed unchanged.
Run a pressure ladder
Set the lvlp spray gun at the lowest pressure that still produces a complete fan. Spray the first zone using two consistent passes. Increase pressure by 0.1 or 0.2 bar for each following zone. Measure pressure only with the trigger fully pulled. Static regulator readings are unsuitable for this test because they do not show line loss during flow.
Inspect the wet film immediately under cross lighting. Heavy orange peel shows broad, rounded texture with valleys that remain visible after the initial solvent flash. Moderate texture may level during flash, while an over-atomized film often looks dry, pale, or dusty at the fan edge. The practical threshold is the lowest pressure that produces small, even droplets and a continuous wet film without excessive overspray.
Read the wet film
If the low-pressure zones show coarse texture, first verify fluid output. Too much material can overload the available atomizing air. Close the fluid control by one-eighth turn and repeat the test. If the high-pressure zones look dry, reduce pressure, shorten gun distance slightly, or select a slower reducer. Do not use pressure alone to correct a viscosity or temperature problem.
A conventional air spray gun may achieve finer breakup at a higher air volume, but this does not automatically create better leveling. Excessive air can cool the surface, increase bounce-back, and accelerate solvent loss from small droplets.
Separate pressure from other variables
Repeat the pressure ladder with the lvlp spray gun on a vertical panel because sag resistance and leveling behavior change with orientation. After cure, compare texture using a gloss meter if available, or place an OEM reference panel beside the test area under the same light. Note the pressure where heavy texture becomes moderate and the point where dry spray begins.
Record nozzle size, mixed viscosity, reducer, panel temperature, dynamic pressure, fluid setting, distance, speed, overlap, and flash time. Use the resulting window as a job-specific reference, not a permanent specification. Recheck it whenever material batch, booth airflow, hose length, regulator, or spray-gun setup changes.
Confirm the cured result
Allow every zone to cure fully before making the final judgment. Fresh clear can appear smoother than the finished film. Evaluate again after the specified bake or air-dry cycle, because solvent contraction can reveal texture that was hidden while wet.
Photograph each cured zone at a fixed angle and distance. Consistent images help the team compare texture objectively, train new painters, and identify whether later deviations came from pressure, material preparation, or application technique.
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