• Temperature too high during application
• Relative humidity too high
• Sudden change in temperature and/or humidity during curing
• Dry application
• Poor extraction and air movement
• Incorrect mixing
• Poor preparation (sanding)
• Application over incompatible substrate
• Flash-off times ignored
• Incorrect use of accelerators
• Using products with expired shelf life
  

Remedies

• Sand and reapply with correct preparation