• Spray gun held too far away from the surface being painted
• Air pressure too high
•  Incorrect viscosity (too much solvent)
• Incorrect spraying pattern (arcing)
• Not triggering off at the end of each pass
• Incorrect gun set-up (over atomization)
• Incorrect routing resulting in poor melt in
• Insufficient air flow or lack of exhaust system
  

Prevention

• Maintain 15-25 cm (conventional) or 35 –45 cm (airless) distance to surface
• Check pressure
• Add the correct amount of solvent by measure or determine by viscosity test (if applicable)
• Ascertain and use correct set up (refer to technical data sheet)
  

Remedies

• Strip and clean or sand down and repaint