• Improper surface treatment or lack of surface treatment (on magnesium)
• Entrapped oils and/or solvents
• Insufficient primer drying times
• Use of improper thinner
• Use of fluid tip: too small or too big
• Material sprayed was too thick
  

Prevention

• Apply manual surface treatment and ensure complete coverage of the magnesium with surface chemical film, before wash primer application
• Microscopic examination of stripped paint removed during tape test
• Check mixing instructions to eliminate use of improper thinners
• Mix in the correct ratios using a measuring stick
  

Remedies

• Strip and clean or sand down and repaint