So, you’ve followed the instructions, applied your epoxy coating perfectly, and now… it’s showing a white bloom. You’re probably thinking, “Is this going to be a problem?” In short, it might be. This phenomenon, called an Amine Blush or bloom, occurs due to ammonium bicarbonate salts forming when there’s a shift in humidity and temperature during the epoxy curing process.
This effects the following products, epoxy mastic 121, zinc epoxy primer, Custom 421 epoxy primer paint and Armaguard rust protection paint,
But before you panic and swear off epoxy forever, let’s dive a little deeper into the issue.
Is It Sticky or Hard? That’s the Real Question
After full curing, take a closer look: is the white bloom hard and dry, or sticky compared to the surrounding area? The answer is important because it determines whether this issue is purely cosmetic or a potential disaster.
If the bloom is sticky, we’ve got a few things to worry about:
- Overcoating failure risk – that’s never fun.
- Aesthetic issues – no one wants an ugly finish.
- Decreased stain resistance – think spills, stains, and a lifetime of regrets.
- Yellowing tendency – like an old newspaper, but way less charming.
- Softness of the coating – you don’t want your epoxy feeling like a sponge.
- Reduced chemical resistance – weakening the epoxy’s durability.
If, however, the bloom has hardened and matches the surrounding epoxy, the issue is mainly cosmetic—annoying but fixable.
This Clear Varnish shows the white of a Bloom
So, What Do You Do Now?
If the bloom is sticky or soft, unfortunately, you’ll have to remove it and reapply the coating. If it’s just aesthetic, lucky you! Here’s how to deal with it:
- Test it: Since amine is alkaline, you can use litmus paper to check if the bloom is still active. Science to the rescue!
- Wash it: Clean the surface with a detergent, but make sure to rinse thoroughly. You don’t want soap bubbles causing more chaos.
- Abrasive love: If that sticky film persists, gently abrade the surface with a Scotchbrite nylex pad. Just be careful—if you’re not planning on overcoating, don’t damage the epoxy, or you’ll be painting again sooner than you’d like.
How Do I Prevent This From Happening Again?
Avoiding the dreaded bloom is easier than you might think. Here’s how to do it:
- Paint on dry days: Low humidity is your friend.
- Avoid cold, damp conditions: Especially foggy winter evenings—unless you’re working in a heated area, that is.
- Use the dew point calculator: Available on our website, this little app will save you from moisture miscalculations. Follow this link to our Dew Point Calculator
- Mix like a pro: Use the exact ratio of component A to B. No guesstimating. B (the hardener) is crucial, so precision is key.
What If You Can’t Avoid Bad Conditions?
If you’re stuck working in less-than-ideal conditions (think maintenance projects or work shutdowns), don’t despair! Reach out to our technical department to learn about our full range of MCU moisture curing urethanes. These coatings laugh in the face of cold and damp environments, letting you work stress-free, no matter the weather.
In the end, whether it’s sticky, soft, or just plain white, epoxy bloom doesn’t have to be a nightmare. With a little knowledge and the right approach, you can tackle it head-on—like a true epoxy warrior.
