Why did your epoxy coatings bubble?

Posted by Pedram Mojarrad on

Have you ever seen bubbles in epoxy floors? do you know why those pop up at all?

Bubbles don't look good in what we expect of resin flooring systems (seamless, consistent looking coatings).



What are they?

These pinholes in the coating appear as small blisters or bubbles. After the blisters pop, they leave round bowl-shaped bubbles that can be seen through the transparent film.



1- Outgassing: Air can escape from the porous substrate and becomes trapped in the coating. So substrate preparation is really important here. 

2- Temperature/Humidity: If too hot or humid, it can result in rapid drying that cause’s air entrapment in the coating.

3- Air Movement: Air movement from wind, fans, door or vents blowing directly on the surface may cause flash drying which causes bubbles.

4- Sunlight: Direct sunlight can cause the product to tack up before necessary air release has occurred, which results in bubbles.

5- Mixing: Mixing at too high of a speed entraps air, resulting in bubbles. Also, excessive use of thinners can cause bubbles in the coating.

6- Surface Prep: Extreme/aggressive shot blasting opens the pores in the concrete causing air to be trapped when the coating is applied resulting in bubbles.

7- Dust in the air. Dusts and debris sitting on wet epoxy paint can cause some bubbles too. 

8- Roller Covers: Not using the proper nap recommended. Short nap sizes are usually better with epoxy products (4 or 5 mm nap size).



• Sand the areas with bubbles, using light sand papers with high grit. Vacuum dust and debris.

• Fill large craters with epoxy patching material.

• Sand patched areas and vacuum.

• Reapply coating at recommended rate and follow directions.




As you can see in the causes mentioned above, the most important thing to do is a proper substrate preparation. You might have heard this before from us, "substrate prep" is even more important than the product or brand.

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