How to Fix Bubbles in Epoxy Resin (Without Ruining Your Project)
If you’ve ever poured epoxy resin, walked away feeling confident, then come back to find bubbles trapped across the surface—you’re not alone.
Bubbles are one of the most common resin issues we hear about. They happen to us all. The good news is they’re usually fixable, and once you understand what causes them, they become much easier to prevent.
Whether you’re coating a tabletop, creating resin art, casting moulds, or sealing timber, this guide will show you exactly how to fix bubbles in epoxy resin and get cleaner, clearer results next time.
Why Do Bubbles Form in Epoxy Resin?
Most bubbles don’t happen by accident—they happen because air gets trapped somewhere during the process.
1. Mixing Too Fast
This is probably the most common cause. If resin is stirred aggressively, it traps thousands of tiny air bubbles into the mix.
They may look harmless at first, but once poured, they rise slowly and can stay suspended as the resin cures.
2. Cold Resin or Cold Weather
Cold resin gets thicker. Thick resin holds bubbles longer and makes it harder for them to rise naturally.
This catches a lot of people out during winter, especially in sheds and garages.
If your resin feels sluggish or syrupy, it’s too cold.
3. Timber Releasing Air (Outgassing)
Wood contains air inside the grain. Once resin is poured over it, that trapped air starts escaping upward.
This is why timber projects often look perfect for ten minutes, then suddenly develop bubbles.
4. Pouring Too Thick
Deep or heavy pours can trap air below the surface before it has time to escape.
5. Moisture or Humidity
Moisture can create cloudiness, foaming, or surface defects. Always keep tools, cups, and surfaces dry.
6. Air Trapped in Moulds or Decorations
Silicone mould corners, dried flowers, shells, glitter, stones, and embellishments often hold hidden air pockets.
How to Fix Bubbles in Wet Epoxy Resin
If your resin is still liquid, you’re in a good position. This is when bubbles are easiest to remove.
Use a Heat Gun
A heat gun is one of the safest and most effective ways to remove surface bubbles.
- Hold it around 15–25 cm above the resin
- Keep it moving constantly
- Use short passes only
The gentle warmth thins the surface and allows bubbles to rise and pop.
Tip: Don’t hover in one spot too long. Too much heat can cause ripples or yellowing.
Use a Small Torch
A butane torch is popular for benchtops and flood coats because it pops bubbles instantly.
Quick pass only. Keep moving.
Most beginners use too much flame, too close, for too long.
Less is better.
Warm the Bottles Before Mixing
If your resin is cold, warm the sealed bottles in lukewarm water for 10–15 minutes before mixing.
This single step can dramatically reduce epoxy resin bubbles. But can reduce working time also.
Use a Toothpick for Detail Areas
Perfect for mould corners, edges, around flowers, or stubborn trapped bubbles.
If It’s Really Bad — Re-Pour It
Sometimes the best fix is honesty.
If the resin is full of foam or microbubbles, scraping it back and re-pouring properly is often faster than trying to rescue it.
How to Fix Bubbles After Resin Has Cured
Once resin has hardened, bubbles cannot be removed—but the surface can usually be repaired.
Sand It Flat
Use wet/dry sandpaper:
- 240 grit to level defects
- 400 grit to refine
- 800+ grit before polishing
Apply a Fresh Top Coat
After sanding and cleaning, apply a new thin flood coat of quality epoxy resin.
This fills pinholes, restores gloss, and gives the project a second life.
Spot Fill Small Holes
For isolated bubble craters, use a small mixed batch and apply carefully with a stick or syringe.
Polish Minor Marks
If the defects are only shallow surface marks, sanding and polishing may be enough.
How to Prevent Bubbles in Future Projects
If you want consistently clear resin, prevention matters more than repair.
Work Between 20°C and 25°C
This is the sweet spot for most epoxy systems.
Too cold = thick resin. Too hot = fast cure.
Mix Slowly
Think fold, not whisk.
Slow mixing introduces far less air.
Seal Timber First
Always apply a thin seal coat on porous timber before the main pour.
This stops most outgassing problems.
Pour in Layers
Several controlled pours usually outperform one oversized pour.
Use Better Resin
This matters more than many people realise.
Premium epoxy resin products are designed for clarity, self-levelling, and cleaner bubble release. Cheap resin often creates more problems than it saves.
Common Bubble Problems & Quick Fixes
| Problem | Likely Cause | Best Fix |
|---|---|---|
| Tiny bubbles everywhere | Mixed too fast | Mix slower and use heat gun |
| Large bubbles in timber | Outgassing | Seal coat first |
| Cloudy bubbly finish | Cold conditions | Warm room and recoat |
| Bubbles in mould corners | Trapped air | Pour slowly and use toothpick |
Expert Tips for Crystal Clear Results
- Let mixed resin sit for 1 minute before pouring
- Use a second heat pass after 10 minutes
- Keep dust away while curing
- Level your project before pouring
- Use deep pour resin for thick castings
- Always measure accurately
Final Thoughts
Learning how to remove bubbles from epoxy resin is part of learning resin properly.
Every experienced resin user has dealt with bubbles. The difference is they know what causes them—and how to stop them early.
With the right technique, proper temperatures, and quality materials, smooth glass-like finishes become normal, not lucky.
If you need help choosing the right product for artwork, timber, moulds, or deep pours, explore our premium epoxy resin range or contact our team for honest advice.
