Causes and how to prevent them

• Epoxy resins and some epoxy primers when cured in cooler or humid conditions, will develop a haze or sticky film on the surface. This is caused by a reaction between the curing agent (hardener) and carbon dioxide and moisture in the air. It usually occurs in cool damp conditions but it may also happen in warm conditions if the humidity is high. 
  Prevention: Use epoxies in warmer drier conditions where possible. Follow recommendations provided by paint supplier.

• Topcoat finishes, especially two pack polyurethanes, can be affected by early evening dew or mist. Moisture developed in the air, or on the surface of the paint, reacts with the surface leading to low gloss or dulled areas on some or all painted areas, but more often it can be seen on horizontal surfaces rather than vertical ones. 
  Prevention: Don’t paint when the paint will remain in a state of cure and exposed to cold damp conditions. Follow recommendations provided by paint supplier.

• Blushing can happen when the paint is applied as the temperature drops. When applying paint to a surface, the evaporation of the solvents requires energy. This is taken from the object being painted, and in turn causes the surface temperature to drop. In cold or very humid conditions, this can cause moisture to form on the surface affecting gloss levels.
  Prevention: Be aware of weather conditions that may occur later in the day or during the early evening. Follow recommendations provided by paint supplier.

How to treat it

• The bloom or blush is easily removed with warm soapy water and the cured epoxy underneath will be unaffected.
• Topcoat paints affected by moisture will require sanding and recoating