Causes:         
    – Excessive coat thickness of the basecoat.
    – Intermediate and final flash off times of the basecoat are too short.
    – Delay between the final coat of the basecoat and the 1st coat of the clear coat.
    – Wrong mixing ratio of clear coat/hardener.
    – Basecoat surface is contaminated (finger marks, sweat, dust, etc.).

Preventive measures:
    – Do not exceed 3 spray passes of basecoat.
    – Observe intermediate and final flash off times.
    – Do not wait too long after spraying the final coat of basecoat. 
      (If a long wait is unavoidable you should sand the basecoat and respray).
    – Use the recommended hardener in the correct mixing ratio.
    – Avoid any contamination of the basecoat before spraying the clear coat.

Remedy:
    – Sand and repaint