HVLP Trouble Shooting Guide

Some solutions to common HVLP troubles. Even if you are not trouble-shooting your HVLP sprayer there is a lot of good information here that can help you spray better finishes.

Problem

Cause

Solution

Orange Peel. 1. Material drying too fast. Slower solvent.
2. Gun too far from surface. Move gun closer to surface.
3. Material too thick. Thin material per thinning instructions.
Runs and sags. 1. Material too thin. Add material.
2. Moving gun too slow. 2. Speed up gun movement.
3. Too much material flow. Turn material knob counter-clockwise to reduce flow.
4. Spray gun too close to surface. Hold gun 8" - 10" from surface.
Pin-holing and solvent pops. 1. Trapped solvents. Apply material in lighter coats allowing solvents time to evaporate.
2. Pigment settling. Possible bad material.
3. System contamination. Thoroughly clean all parts.
Fish eyes. 1. Possible silicone contamination. Use solvent to clean all parts.
Blistering. 1. Moisture in/on surface. Dry surface.
2. Incompatible top coats or undercoats. Make sure coatings are compatible.
Lumpy, coarse surface. 1. Dirt on surface. Thoroughly clean surface.
Mottled surface finish. 1. Too much thinner. Reduce thinner.
2. Poor spray technique. Follow spraying instructions in the owners manual
No material flow. 1. Clogged nozzle/air cap. Disassemble and clean.
2. Clogged cup pressure tube. Disassemble and clean.
3. Clogged gun. Disassemble and clean.
4. Clogged material hose. Disassemble and clean.
5. Poor cup seal. Inspect seal in cup cap and clean or replace as necessary.
6. Excess particles in paint. Strain paint.
Slow material flow. 1. Material too thick. Clear material hose of thick material and thin material per thinning instructions.
2. Improper material adjustment. Turn material adjustment knob until desired flow is achieved.

 
4. Poor air flow through filter. Remove and clean or replace filter.
5. Excess particles in paint. Strain paint with filter.
Material leak. 1.Damage to cup or gun. Check cup or gun and replace damage parts.
2. Loose packing. Tighten packing per instructions.
3. Worn or damaged packing. Remove and replace.
4. Worn or damaged cup seal. Remove and replace.
5. Loose cup fittings. Tighten.
6. Loose nozzle. Tighten.
7. Wrong needle/ nozzle assembly. Refer to material application chart for correct combination.
8. Damaged needle. Replace.
9. Loose material adjuster. Turn clockwise until needle seals in nozzle.
Pulsating spray. 1. Check cup seal. Disassemble and clean.
2. Check packing. Tighten per instructions.
3. Loose fitting on cup or gun. Tighten.
4. Loose air cap retainer ring. Tighten.
5. Loose nozzle. Tighten.
6. Damaged air flow ring. Replace.
7. Excess particles in paint. Strain paint.
Excessive overspray. 1. Material too thin. Thicken by adding paint.
2. Too much air flow. Adjust air flow.
3. Wrong needle/nozzle. See material chart.
4. Gun held too far from surface. Move 8" - 10" from surface.
5. Wind. Do not use in windy conditions.
6. Too much material. Turn material knob counter-clockwise to reduce flow.
7. Excess particles in paint. Strain paint.
Spitting. 1. Material too thick. Thin per recommendations.
2. Wrong needle/nozzle. See material chart.
3. Coup not sealing. Tighten or replace seal.
4. Packing loose. Tighten or replace seal.
5. Excessive particles in paint. Strain paint.
Poor pattern. 1. Build-up on nozzle. Clean nozzle and air cap.
2. Wrong needle/nozzle. Replace.
3. Clogged air cap. Clean.
4. Excessive particles in paint. Strain paint.
Overheating. 1. Clogged filter. Replace.
Poor air flow. 1. Clogged filter. Replace.
2. Hose kinked. Move so that kinking does not occur.
3. Air flow control out of adjustment. Adjust air flow.
Spray not uniform (spitting). 1. Material too thick. Check material viscosity (Thin per instructions).
2. Wrong needle/nozzle assembly. Change to proper needle/nozzle.
3. Cup seal leaking. Tighten cup, replace seal or check valve.
4. Loose packing. Adjust or replace packing.
5. Material not properly mixed, or improperly filtered. Strain paint.
Poor pattern. 1. Material buildup on nozzle or air cap. Clean nozzle and air cap.
2. Worn nozzle/needle. Replace.
3. Clogged air cap. Clean.
4. Material not properly mixed, improperly filtered. Strain paint.
Overheating. 1. Clogged filter. Replace.
Poor air flow. 1. Clogged filter. Replace filter.
2. Air flow control improperly adjusted. Adjust air flow control.
Spray tip clogs. 1. Improper material flow adjustment. Adjust material control.
2. Cup seal leaking. Replace cup seal.
3. Wrong needle/nozzle. Change to proper needle/nozzle.
Orange Peel. 1. Material drying too fast. Use a slower solvent, or add a retarding agent.
2. Gun too far from surface. Move gun closer to surface.
3. Material too thick. Thin material per thinning instructions.
Runs and sags. 1. Material too thin. Add material to increase thickness.
2. Moving gun too slow. Move gun more quickly.
3. Excessive material flow. Turn material control knob clockwise to reduce flow.
4. Gun too close to surface. Move gun further from surface.
Pin-holding and solvent pops. 1. Trapped solvents. Apply material in lighter coats allowing solvents time to evaporate.
2. Pigment settling. Possible bad material.
3. System contamination. Thoroughly clean all parts.

 

 
Fish eye. 1. Possible silicone contamination. Use solvent to clean all parts.
Blistering. 2. Moisture in/on surface. Dry surface.
3. Incompatible top coats or undercoats. Make sure coatings are compatible.
Lumpy, coarse surface. 1. Dirt on surface. Thoroughly clean surface.
Mottled surface finish. 2. Too much thinner. Reduce thinner.
3. Poor spray technique. Refer to "Operation" for spraying instructions.
No material flow. 1. Clogged nozzle/air cap. Disassemble and clean.
2. Clogged cup pressure tube or fittings. Disassemble and clean (a straight pin can be used to clean fittings).
3. Clogged gun. Disassemble and clean.
4. Clogged material tube. Disassemble and clean gun, and check valve.
5. Cup seal leaking. Inspect cup seal, cup cap, and clean and replace as necessary.

 
6. Material not properly mixed, or improperly filtered.