What are the Best Methods for Preventing Bubbles in Polyaspartic Topcoats?
The best method for preventing bubbles in polyaspartic topcoats is to seal the concrete with a moisture-tolerant basecoat and apply the topcoat using proper mixing and rolling techniques. Controlling substrate conditions, mixing ratios, and environmental factors also plays a crucial role in ensuring a bubble-free finish.
Bubbles in polyaspartic topcoats can ruin an otherwise flawless concrete coating job, leading to poor aesthetics, compromised durability, and costly rework. Whether you’re a seasoned contractor or just starting out, mastering bubble prevention is key to delivering professional-grade results every time.
We help concrete coating supply professionals across the U.S. avoid issues like bubbling through high-performance systems. In this guide, you’ll learn exactly what causes bubbles, how to stop them before they start, and proven techniques for applying smooth, durable polyaspartic coatings.
Why Bubbles Are a Big Problem in Polyaspartic Coatings
Bubbles are not just a cosmetic concern. They can:
- Compromise adhesion
- Reduce durability
- Create weak spots prone to chipping or delamination
- Reflect poorly on your craftsmanship
That’s why preventing bubbles from the start is far easier (and cheaper) than fixing them after the fact.
What Causes Bubbles in Polyaspartic Topcoats?
Before we can prevent bubbles, we have to understand where they come from. Here are the top causes of bubbling in polyaspartic coatings:
1. Outgassing from the Concrete Substrate
Concrete is porous and can trap air or moisture. When you apply a topcoat—especially in warm conditions—the trapped air escapes upward, causing bubbles.
2. Improper Mixing Techniques
Aggressive or high-speed mixing can introduce air into the coating, which later rises to the surface during application.
3. Off-Ratio Mixing
Incorrect ratios of part A and part B can create a foamy, bubbly texture and poor chemical crosslinking.
4. High Humidity or Temperature
Environmental conditions impact polyaspartic floor coatings. High temperatures accelerate cure times, trapping air. High humidity can create moisture vapor pressure, which leads to bubbles and blisters.
5. Application Over Damp or Contaminated Surfaces
Applying a topcoat over damp concrete, oil residues, or dust can interfere with adhesion and lead to bubbling.
6. Improper Roller or Squeegee Use
Using the wrong nap roller or too much pressure can push air into the coating. Fast rolling or back-rolling can also whip air into the product.
9 Proven Methods for Preventing Bubbles in Polyaspartic Topcoats
Here’s what the pros in other concrete coating companies—and our AllSource training team—recommend as best practices to ensure bubble-free finishes:
1. Always Use a Compatible Primer/Basecoat
Start with a moisture-tolerant basecoat like Hardbond Polyurea Basecoat, which seals the concrete and prevents outgassing. This acts as a buffer and dramatically reduces the chance of bubbles migrating into the topcoat.
💡 Tip: Let the basecoat fully cure and inspect for defects before topcoating.
2. Moisture and Vapor Testing
Test the concrete slab for moisture using a concrete moisture encounter. Excess moisture can lead to vapor drive that causes bubbling.
If the slab is above the recommended limits, consider using a vapor barrier primer before applying your polyurea or polyaspartic system.
Tramex Concrete Moisture Encounter
3. Control the Environment
Keep the workspace between 60°F and 80°F with less than 50% humidity for best results.
High temps accelerate curing, leaving less time for air to escape. High humidity can cause moisture-related bubbling. Use fans, dehumidifiers, or HVAC systems as needed.
4. Use Low-Speed Mixing Blades
High-speed mixing traps air. Use a low-speed (300-450 RPM) drill with a Jiffy-style blade and mix each component separately before combining.
Once mixed, let the product “induct” for 2–3 minutes to allow bubbles to rise before application.
5. Mix Correctly—Use a Digital Scale
Eyeballing won’t cut it. Use a digital scale for accurate mix ratios. Off-ratio mixing causes foaming, uneven cure, and reduced performance.
6. Use a Spike Roller if Needed
On thicker builds, a spiked roller can help release trapped air without damaging the coating. This is especially helpful in the first few minutes after application.
7. Use Solvents with Caution
Some applicators use solvents like xylene to pop bubbles. This should be a last resort. If you must use it, apply a light mist from a distance right after application, not during cure.
Pro tip: With quality concrete coatings supply like Allsource’s polyaspartic, proper technique should eliminate the need for solvents entirely.
8. Watch Your Pot Life
Polyaspartics cure fast. Don’t let the mix sit in the bucket—pour it out onto the surface immediately to extend the working time and reduce heat buildup that can cause bubbling.
Use smaller batches if necessary.
9. Sand and Recoat if Needed
If bubbles appear and harden, sand them down using a 100–120 grit screen. Vacuum and tack cloth the surface, then reapply a fresh layer.
A System that Helps Prevent Bubbles from the Start
Bubbles in polyaspartic topcoats often begin at the substrate level or during application. The Polyurea Solid Color System is engineered to address these issues from the outset by combining proper surface preparation, moisture control, and high-performance chemistry.
System components include:
- Hardbond Polyurea Basecoat – Designed for superior adhesion and excellent moisture tolerance, this base layer helps prevent outgassing and vapor-related bubbles.
- Optional Quality Vinyl Flake Layer – Not only enhances visual appeal, but it also contributes to hiding minor surface imperfections that can lead to uneven topcoat finishes.
- Hardbond Polyaspartic Topcoat – A UV-stable, fast-curing, and self-leveling formulation that resists bubbling when applied using proper techniques.
As one of our customers says:
Awesome one stop shop for all of your concrete coatings supply. We have been using their polyurea and polyaspartic products with great success for many years. Super friendly and very knowledgeable. We highly recommend them! — Greg Beebe
Allsource’s Polyurea Basecoat
To support consistent, high-quality results, Allsource Supply provides professional resources, including hands-on floor coating training, to ensure contractors can execute clean, durable installations with confidence.
Common Questions About Polyaspartic Bubbles
- Can I fix bubbles once the coating has cured?
- Yes. Lightly sand down the bubbles, vacuum thoroughly, and apply a new coat. For deep bubbles, you may need to patch with additional polyaspartic or grind back to the basecoat.
- Are bubbles more common in hot climates?
- Yes. High temperatures reduce working time and increase the risk of bubbling. Always adjust your process based on weather—use slower-cure formulas or work during cooler times of day.
- Can I apply polyaspartic coatings in humid conditions?
- You can—but it requires more care. Monitor dew point, use dehumidifiers if needed, and avoid coating if the substrate is colder than the dew point (which can cause condensation and blistering).
- How long should I wait between basecoat and topcoat?
- Wait until the basecoat is fully cured and no longer tacky. Depending on conditions, this may be 2–4 hours or longer. Always test a small area before full application.
Final Thoughts: Bubble-Free Coatings Start with the Right System and Technique
Bubbles in polyaspartic topcoats are avoidable with the right process, materials, and training. Whether you’re doing residential garages, commercial showrooms, or industrial warehouses, following these best practices will ensure a clean, durable, and professional finish every time.
Visit or call our Allsource team (833-663-4255) to get help with your next job, and leave bubbles in the past.
With over two decades in the construction industry, Roy Magnuson has cultivated a deep expertise in concrete repair and coating applications across various environments. His early passion for decorative concrete led him to co-found Allsource Supply Inc. in 2013, a family-owned business based in Oshkosh, Wisconsin. Under his leadership, the company has become a trusted provider of high-quality concrete coatings, equipment, and contractor supplies, serving professionals nationwide. Roy's commitment to customer-centric service ensures that clients receive not only top-tier products but also the expert advice needed to get the job done right.
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