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Why is there a white, waxy surface on the top of the coating? (Epoxy/Amine Bloom)

What is it?

This is an issue known as “Epoxy Bloom” more commonly known as “Amine Bloom”, often identified by a white, waxy surface on top of the coating.

Amine Bloom

Common Causes:

Moisture – This is the most likely cause of bloom and is generally due to the introduction of moisture during the cure process. If the epoxy meets any moisture/humidity/condensation/dew, this can cause the epoxy to bloom during the curing process causing a patchy surface.

Other external processes such as gas space heaters can also introduce moisture.

 

Reaction with substrate - This can happen due to the ammonium bicarbonate salts reacting during a change in humidity and temperature as the epoxy is curing, causing them to rise and form a white/waxy surface.

 Although bloom generally will not affect an epoxy coatings durability, the surface will look very patchy, almost like a worn floor, which we understand is not appealing.

So, how would I resolve this?

  •  A re-coat with one further coat to provide a uniform coat across the full surface would be the best recommendation.
  • If the coating has been down for more than 48 hours, you will need to gently sand the surface with a fine/medium grit sandpaper to create a mechanical key, ensuring all debris is removed upon sanding.