You spent hours on this piece.The colors were perfect. The design looked exactly right. Every detail was where it should be.Then you opened the mold.One small bubble.And suddenly, everything felt ruined.
The good news? Resin bubbles can be fixed—and most of them can be prevented.
Whether bubbles appear during mixing or after pouring, creators usually solve them by warming the resin, mixing slowly, letting the resin rest, pouring carefully, using gentle heat on surface bubbles, choosing the right resin type, or using a vacuum bubble remover for the cleanest results.
Once you understand when bubbles form and which method fits your project, cleaner pours become much easier.
In this guide, bond craftor break down why resin gets bubbles, how to remove them before and after pouring, and how to stop them from happening in the first place.You already spent time on the design. Your next piece doesn’t need to be ruined by air.
💡TIP: New to resin and not sure what to buy first? Start with this resin type guide.
Table Of Contents:
Why Are There Always Air Bubbles in Resin?
Resin is a liquid, and during mixing, liquids naturally trap pockets of air. That trapped air becomes bubbles inside the resin.
Some bubbles are introduced the moment you start mixing the resin and hardener. More can form while pouring into a mold. Others appear as the mixture settles on your workbench.
Some bubbles rise to the surface and pop on their own. That’s the easy part.Others stay trapped inside the resin, especially in:
High-viscosity resin (thicker resin that flows slowly) — bubbles rise more slowly
Deep Pour Epoxy projects — bubbles may not have enough time to escape before curing begins
Detailed Resin Silicone Molds — bubbles often get stuck in corners, lines, and small recesses
As epoxy resin cures, it begins to warm and harden. Trapped bubbles can expand and leave holes, cloudy spots, or surface defects behind.That’s why professional-looking resin pieces often look cleaner. It’s not luck. It’s process.Most experienced makers remove bubbles before they pour—not after.
💡TIP: Using molds with fine details? Clean molds correctly to reduce trapped bubbles and surface defects.
When Do Bubbles Appear: Before Pour vs. After Pour
Before Pouring: Bubble formation usually starts during mixing. Stir too fast? Bubbles. Pour from too high? Bubbles. Use older resin? Sometimes, more bubbles.
This is the easiest stage to solve the problem.
After Pouring: Once resin is inside the mold, bubbles become harder to control. Surface bubbles may rise and pop. Deeper bubbles often stay trapped until the resin cures.
Here’s the key idea: removing bubbles before pouring is much easier than fixing them later.
Before Casting: Preventing Problems Before They Occur
If you're not already using any air bubble removal methods, this is where you start. These techniques can eliminate most of the air before your resin enters the mold.
Method 1: Heating the Resin
Low-viscosity resins (resins with good flowability) are generally easier to defoam because bubbles rise to the surface more quickly. Heating the resin lowers its viscosity—essentially making it thinner and allowing bubbles to escape more easily.
How to do it: Place the resin bottle in warm water (not boiling water, just lukewarm) for about 5-10 minutes, or use a heating pad or heat lamp (keeping it around 120-160°F / 50-70°C).
After mixing the resin and hardener, let the mixture stand in the warm environment for 5-10 minutes. The bubbles will begin to rise and burst on the surface.
When to use it: If you are doing Deep Pour Epoxy or any thick pour (in which case bubbles are difficult to rise naturally), heating is your friend. Disadvantages: This only helps bubbles that want to rise. Those that are truly trapped? Heating won't help.
💡TIP: Working on a thick pour or river table project? See why deep pour epoxy handles bubbles better in thick layers.
Method 2: Slow and Steady Stirring
One of the main causes of air bubble formation is stirring too fast. When you stir resin quickly, you're not just mixing the ingredients—you're whipping air in. What looks like thorough stirring is actually full of tiny air bubbles.
How to do it: Stir slowly. I'm serious. Don't impulsively stir fast. Use a stirring stick to stir slowly in a circular motion at a speed of about 1-2 revolutions per second (not 10 revolutions per second) for 2-3 minutes, making sure all the hardener is thoroughly mixed. If possible, place the container in warm water while stirring (warm water + slow stirring = ideal).
Why it works: When you stir slowly, you give air bubbles time to rise to the surface instead of letting them get trapped in the mixture.
Method 3: Careful Pouring
Pouring resin from a height is a hidden air bubble maker. When you pour, the resin falls from a height, causing air bubbles to form. Small pours = small impacts = fewer air bubbles.
How to do it: Lower the pouring cup (or the container you're pouring into) as close as possible to your mold.
Pour along the inside of the measuring cup or mold, allowing the resin to flow in slowly rather than pouring directly into the center. Avoid pouring from a height of more than 6 inches.
👉 Why it works: Reduced impact = less air bubbles. Simple.
Method 4: Resin Bubble Remover
A Resin Bubble Remover(also called a vacuum foam remover) is a simple yet powerful tool. When you reduce the air pressure inside the container, bubbles in the resin expand, rise to the surface, and are then sucked out.
The principle is simple: Place your resin (before pouring) into the vacuum chamber, close the lid, press the button, and the machine begins to evacuate the air from the chamber. As the pressure drops, the air bubbles in your resin expand, rise to the surface, and are sucked out by the suction. After a few minutes, you open the lid—your resin is now truly bubble-free, and you will see the whole process happen—the bubbles rise from the resin and are sucked away. It's satisfying.
💖 Why it works: Unlike other methods, vacuum degassing removes not only surface bubbles. It removes all bubbles—surface, deep, tiny, and large.
When to use: Before pouring (best) If you frequently work on resin projects, if you use high-viscosity resins or do deep pouring, or if you require a high-quality finished product, "vacuum degassing" is the closest thing to a the most reliable solution for creators who want repeatable, cleaner results. to the bubble problem.
Bond Craftor Resin Bubble Remover
3.4L Resin Bubble Remover - 98 KPa Vacuum Pressure Vacuum Machine
Shop NowMethod 5: Choose the Right Type of Resin
Different resin projects require different resins—understanding what you're making will be very helpful.
For detailed work and small items (such as jewelry and trinkets) – choose Craft Epoxy – these resins have lower viscosity, flow more easily, and de-bubble more readily. They produce fewer bubbles when mixed, and the bubbles rise more easily.
For large pours and thick layers – Deep Pour Epoxy is specifically designed to handle thick layers; however, it has a higher viscosity (thicker), meaning bubbles may take longer to rise. For these projects, de-bubbling before pouring becomes even more critical.
For projects requiring rapid curing – Fast Cure Epoxy starts curing faster, so you have less time for bubbles to rise. If you are using a fast-curing resin, de-bubbling before pouring is especially important.
Choosing a resin designed for your specific project, rather than trying to do everything with one resin, can significantly reduce bubble problems.
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| Category | Table Top Epoxy | Deep Pour Epoxy | Floor Coating Epoxy | Craft Epoxy | Fast Cure Epoxy | Polyurethane Resin |
| Ratio | 1:1 | 2:1 | 2:1 | 1:1 | 1:1 | 1:1 |
| Working Time | 30–35 min | 2–6 h | 20–30 min | 35–40 min | 25 min | 2 min |
| Initial Cure | 8 h | 50–72 h | — | 12 h | 4–6 h | 10 min |
| Full Cure | 24 h | 72–168 h | 2–3 days | 24 h | ~12 h | 10 min |
| Hardness | 83D | 82–84D | 82±3D | 85D | 78±5D | 75D |
| Features | Crystal clear, high gloss, UV resistant | Thick pour, low heat, bubble release | Wear resistant, self-leveling, stain resistant | Clear, low odor, easy to use | Fast curing, efficient workflow | Ultra-fast, strong, impact resistant |
| Best For | Tabletops, bar tops, surface coating | River tables, thick pours, large casting | Garage floors, concrete coating, industrial use | Jewelry, molds, coasters, DIY crafts | Quick repairs, small projects, fast work | Prototypes, small parts, fast casting |
After Pouring: When Surface Bubbles Appear
Sometimes, despite your best efforts, bubbles will still rise to the surface. These bubbles can still be eliminated before the resin cures.
Using a Heat Gun
A heat gun (also called a baking gun or hot air gun) is a simple way to remove surface bubbles.
How to do it: Set the heat gun to medium temperature (not the highest setting—you don't want to boil the resin).
Quickly sweep the heat gun across the resin surface from about 6-8 inches away. Surface bubbles will burst and disappear due to the heat. Continue sweeping until you can no longer see surface bubbles.
Why it works: Heat causes bubbles to expand and burst. This works well for surface bubbles, but not for deep bubbles.
🚨Warning: If you stay in one place for too long, you may burn dents into the resin surface. Sweep quickly and don't linger.
Your Next Piece Can Be Better
You spent hours on this piece. Your design is perfect. Your colors are accurate.
Then a single air bubble ruins everything. This happens far too often. But it shouldn't be like this.
The key realization is this: Air bubbles are not inevitable. It’s not because you did everything wrong. You just didn't know how to stop them. Now you know. Air bubbles form when the resin is mixed. They form when poured. Some will float to the surface on their own. Many won't.
However, if you: use the correct type of resin for your project (check out Bond Craftor Craft Epoxy, Deep Pour Epoxy, Fast Cure Epoxy to see which one is best for you), stir slowly and steadily, pour gently, remove air bubbles before pouring (using heating, resting, or vacuum degassing), and gently treat surface bubbles after pouring (if needed)
Great resin work is rarely about luck.It’s about process.Once you control bubbles before pouring, everything gets easier.Your next piece can look the way you imagined it.
💡TIP: If you are coating a wood table or countertop, leveling matters as much as bubble removal. See how to epoxy a tabletop step by step.
Important Note: Match Your Method to the Resin Type
⚠️Not every resin gives you the same working time. Before using any bubble-removal method, always consider the resin type and how long it stays workable.
Some formulas cure much faster than others. Fast Cure Epoxy, Roller Coating Epoxy, and many Polyurethane Resin systems can begin setting quickly, which means you may only have a short window to mix, pour, level, and remove bubbles.
If you spend too long heating, stirring, or trying multiple correction methods, the resin may already start thickening before you finish.
How to Remove Bubbles from Resin FAQs:
Find quick answers before you start your resin project.
What if I already poured the resin and now I see bubbles?
Once the resin starts to thicken or gel, trapped bubbles are much harder to fix and may remain in the final piece.
Is a vacuum bubble remover really worth it?
For occasional projects, warming the resin, mixing slowly, and pouring carefully can still work very well.
Why do I get more bubbles than my friend using the same resin?
Small process changes often create much cleaner results.
How long does it take for bubbles to rise out of resin?
In thick resin or deep pours, some bubbles may never rise before curing starts.
Can a heat gun damage resin?
Too much heat may cause ripples, dents, overheating, yellowing, or faster curing than expected.
Can I sand bubbles out after the resin cures?
If bubbles are deep or widespread, repairs become harder and may not fully match the original finish.