What Is Normal and Why Do Bubbles Occur?
At AD Technology, we offer a variety of epoxy flooring options tailored to your needs — including stunning metallic epoxy floors and durable solid color epoxy coatings. Both types bring unique beauty and performance to commercial and residential spaces.
During installation of these epoxy systems, it is common to notice small bubbles or pinholes appearing on the floor surface. But why do these bubbles form? Are they avoidable? And if they do appear, are they acceptable or a sign of poor quality? In this section, we explore the causes of bubbles in metallic and solid color epoxy floors, discuss industry standards on their acceptability, and explain how professionals work to minimize them for the best possible finish.
Why Small Bubbles Appear in Epoxy Floors — And When They’re Acceptable
Epoxy floors — whether metallic or solid color — are seamless, liquid-applied flooring systems. As with any fluid coating, air and gas can become trapped during the installation process. When these gases escape as the epoxy cures, they can leave behind small surface bubbles or pinholes. Here’s what you need to know:
Common Causes of Bubbles:
- Outgassing from concrete: One of the most frequent causes is air or moisture vapor escaping from the concrete substrate. This is why proper surface preparation and, in many cases, applying a moisture vapor barrier is critical — especially on new or porous slabs.
- Mixing technique: Overmixing or fast mechanical mixing can introduce excess air into the epoxy resin. Skilled installers use slow-speed mixers and allow the mix to “sit” briefly to release trapped air.
- Application in high temperatures or direct sunlight: Warm surfaces can increase substrate outgassing and reduce working time, which can contribute to bubbling, especially in thin topcoats or sealers.
- Metallic movement: In metallic epoxy, the flowing, artistic effects are created by chemical reactions and self-leveling movement. This makes them more vulnerable to minor surface tension disruptions, which may include tiny bubbles as the material settles.
- Porous or improperly primed surface: Skipping primer or working on rough/absorbent surfaces without sealing can cause air to pull through the epoxy layer, leaving behind imperfections.
Are Small Bubbles Acceptable?
Bubbles form when air or gases become trapped in the epoxy during mixing, application, or curing. In metallic epoxy floors, the swirling and mixing of metallic pigments can introduce additional air, making small bubbles more noticeable. In solid color epoxy floors, bubbles may appear due to rapid curing, temperature fluctuations, or substrate moisture outgassing.
In most professional installations, tiny surface bubbles or pinholes are considered a normal and acceptable part of the system — especially in metallic epoxy floors where the design is highly dynamic. These imperfections are usually minimal, do not affect performance, and are often invisible from a standing distance. They do not indicate a failure of the system if:
- The floor is properly bonded to the substrate
- There are no signs of peeling or delamination
- The bubbles are cosmetic, not structural
- They do not compromise slip resistance or cleanability
Minor surface bubbles usually do not compromise the floor’s structural integrity or performance. In fact, a small amount of bubbles (often less than 1-2 bubbles per square foot) is generally accepted in industry standards for epoxy coatings. These tiny imperfections tend to be cosmetic and may be less visible once a clear topcoat is applied.
Can They Be Prevented Entirely?
While experienced epoxy contractors take numerous steps to minimize bubble formation — including temperature control, substrate testing, vacuuming, and degassing the mix — it’s virtually impossible to guarantee a 100% bubble-free result in all environments. Factors like slab condition, humidity, and the type of epoxy used all play a role.
A completely bubble-free epoxy surface is extremely difficult to achieve, especially with decorative metallic epoxy, which requires dynamic mixing and application techniques to create its characteristic swirling patterns. Minor pinholes or bubbles are generally considered acceptable and do not affect the performance or durability of the floor. In contrast, solid color epoxy floors typically have fewer bubbles due to simpler application methods, but minor imperfections can still occur.
That said, at AD Technology, we always aim for the best possible finish. We carefully evaluate each slab, recommend moisture mitigation systems when needed, and use high-quality products and expert techniques to minimize imperfections.
How Do Professionals Minimize Bubbles in Epoxy Floors?
While small air bubbles can appear even under ideal conditions — especially in metallic or solid color epoxy floors — a skilled epoxy flooring contractor knows how to minimize them for a clean, long-lasting finish.
Here’s how we minimize bubbles in epoxy applications:
✅ Controlled Mixing
We mix resin and hardener at the correct speed and for the right duration to avoid trapping excess air into the system. Over-mixing is a common cause of microbubbles.
✅ Deaeration Roller (Spiked Roller) Application
Immediately after pouring the epoxy, we run a spiked roller across the surface to release trapped air before the material begins to cure. This step is especially important for self-leveling and metallic epoxy systems.
✅ Environmental Control
We install coatings in climate-controlled conditions whenever possible. Excess humidity, rapid temperature changes, or a cold substrate can lead to bubbling, blushing, or poor curing.
✅ Thin, Even Coats
Applying multiple thinner coats rather than a single thick layer reduces the chance of bubbles rising and getting trapped in the resin.
While minor pinholes or bubbles are considered normal in some decorative epoxy applications (especially metallics), these professional practices keep them to a minimum and ensure a smooth, high-performance floor.
Whether we’re working on an epoxy garage floor or a USDA-compliant commercial kitchen, our epoxy flooring installers ensure your surface is as smooth and durable as it is beautiful.
Moisture Testing and the Importance of a Vapor Barrier
Before applying an epoxy system, it’s essential to ensure that the concrete substrate is not emitting excessive moisture. Even if the surface feels dry to the touch, moisture can rise from within the slab and cause bubbling, hazing, or delamination — especially problematic with metallic and solid color epoxy floors, where visual clarity is key.
If moisture levels are too high, we always recommend to apply a moisture vapor barrier coating to protect the system and ensure a long-lasting bond.
A vapor barrier:
- Blocks moisture from migrating up through the slab
- Enhances epoxy adhesion
- Prevents bubbling and surface defects
- Extends the life of the floor
👉 Learn more about how vapor barriers protect epoxy flooring here: Moisture Vapor Barrier — Why It Matters.
In Summary:
Small surface bubbles in metallic and solid color epoxy floors are normal and typically acceptable within industry quality standards. They do not usually affect the floor’s performance and can often be minimized or concealed with proper topcoats. However, consistent or large-scale bubbling should be addressed promptly to maintain the floor’s integrity and aesthetic appeal.
If the bubbles are extensive or accompanied by other issues like delamination or peeling, it’s best to consult a professional flooring contractor. They can diagnose underlying causes such as moisture problems and recommend appropriate repairs or substrate treatments. Experienced epoxy installers understand these challenges and tailor their process accordingly.
📌 Want to learn more about metallic epoxy floors or solid color epoxy coatings?
Explore our coating systems or contact our team for a free consultation on the right solution for your space.
