If your epoxy has bubbles, the right fix depends entirely on where the bubbles are. There is no single tool that removes them all, and using the wrong one wastes time or ruins the piece. Surface bubbles, the ones that rise to the top within a few minutes of pouring, are a heat job: a torch or heat gun pops them in seconds while the resin is still wet. Trapped bubbles deep inside a thick casting are a pressure job: only a pressure pot, run at 40-60 PSI for the entire cure, can crush them down to invisible. A heat gun cannot reach below the surface skin, and a torch cannot fix a casting that has already cured. Get the bubble type right first, then pick the tool from the comparison table below.
The two kinds of bubbles (and why the fix differs)
Key numbers: Surface bubbles clear with a torch or heat gun in seconds; deep castings need a pressure pot at 40-60 PSI; nothing removes bubbles once the resin has cured.
Almost every bubble problem falls into one of two buckets, and they behave like opposites.
Surface bubbles sit at or just under the top of the pour. They are buoyant, they rise quickly, and in the first few minutes they are still moving toward the surface where heat can burst them. These are the bubbles a torch or heat gun is built to clear.
Trapped (deep) bubbles are locked inside the body of the casting. They cannot rise because the resin around them is too thick, too cold, or too far below the surface to escape before the resin gels. Heat does nothing for these because heat only affects the top millimeter or two. Once the resin cures, deep bubbles are frozen in place permanently.
The single most useful habit in resin work is asking, before you reach for any tool: are these bubbles on the surface, or trapped inside? That one question routes you to the correct fix every time.
What actually causes surface bubbles
Three things put air into the top of your pour:
- Mixing. Stirring fast or whipping the resin folds air in. Stir slowly and deliberately for 4-6 minutes, scraping the sides and bottom, and you fold in far less.
- Cold resin. This is the hidden culprit behind most “mystery” bubbles. Below roughly 70-75 F, epoxy thickens, holds onto micro-bubbles, and can even turn cloudy. The ideal working range is 70-80 F (24-30 C) for both the resin and the room.
- Porous substrate off-gassing. Wood, paper, dried flowers, and unsealed canvas hold air in their pores. As the resin warms during its exotherm, that air expands and burps up through the coating as a steady stream of fresh bubbles, sometimes for an hour. A thin seal coat first stops this.
What causes deep, trapped bubbles
Deep bubbles are a viscosity-and-geometry problem. High-viscosity resin, cold resin, a thick single-lift pour, or sloppy pouring technique all trap air below the surface where it cannot escape. The classic failure is pouring a deep casting all at once: the resin is so tall and so thick that air in the middle simply cannot travel to the top before the resin sets. The fix is partly technique (layer deep pours in ~2 in / 5 cm lifts) and partly equipment (a pressure pot for the pour you cannot layer).
Which tool for which bubble
Surface bubbles: a torch or heat gun in seconds. Deep, trapped bubbles in a thick casting: only a pressure pot at 40-60 PSI compresses them away.
Here is the decision tree in one line each, and the full numbers are in the comparison table below.
- Surface bubbles, want speed: torch (Bernzomatic TS8000).
- Surface bubbles, want safety / large area / open flame is risky: heat gun (Wagner HT1000).
- Deep bubbles in a thick casting (dice, cubes, deep molds): pressure pot (TCP Global 2.5-qt) at 40-60 PSI for the full cure.
- Bubbles in silicone molds or liquid you want gone before pouring: vacuum chamber to degas first.
If you only want to understand the trade between heat tools, we go deeper in heat gun vs torch for resin bubbles.
Fix 1 — The torch: fastest for surface bubbles
A torch like the Bernzomatic TS8000 is the fastest fix for surface bubbles on tabletops and art pours - one or two light passes, kept moving so you do not scorch the resin.
A torch is the professional’s choice for surface bubbles because heat does the work instantly. The Bernzomatic TS8000 outputs roughly 12,936 BTU/hr on propane (12,327 on MAP-Pro) with a flame temperature near 3,400 F (propane) to 3,650 F (MAP-Pro). That heat thins the resin skin and pops the bubble before the surrounding material even warms up.
Technique matters more than the tool:
- Hold the flame 2-4 inches above the surface.
- Keep it moving in smooth passes; never hover.
- Use 1-3 second passes and let the surface settle between them.
The failure mode is lingering. Stay in one spot and you get fisheyes, dimples, or a grainy, sticky scorch that no amount of further heat will fix. Heat sweeps the surface; it does not “cook out” deep bubbles, so if bubbles keep returning after a pass, they are off-gassing from a porous substrate, not sitting on top, and you need a seal coat instead.
Fix 2 — The heat gun: the flame-free option
A heat gun trades a little speed for a lot of safety. The Wagner HT1000 runs 1200 W (~4,100 BTU) with two temperature settings (750 F and 1000 F) and two fan speeds, plus an integrated stand. Because there is no open flame, it is the right call for beginners, for large surfaces where you would be waving a flame around for a long time, and any time alcohol inks or solvents are on the bench.
The catch is airflow. A heat gun moves a lot more air than a torch, so it can blow dust onto a wet surface or push resin around at the edges of a pour. Use the low fan speed, keep it a few inches away, and work in quick back-and-forth sweeps. Held too close or too long it will scorch and yellow the coating just like a torch. And like a torch, it cannot touch anything below the surface skin.
Fix 3 — The pressure pot: the only fix for deep castings
For trapped bubbles in a cube, dice, pendant, or any thick mold, heat is useless and a pressure pot is the only thing that works. The principle is Boyle’s law: increase the pressure and the trapped air shrinks. At 40-60 PSI (small TCP Global mini pots typically work around 30-45 PSI and run near 50 PSI for casting, resin-dependent) each bubble compresses to a fraction of its size, becoming effectively invisible.
The non-negotiable rule: the casting must stay pressurized for the entire cure, often 12-24 hours or longer. The resin sets around the shrunken bubbles and locks them at that tiny size. Depressurize early and the compressed air re-expands right back into the piece, undoing everything. A pressure pot also needs a separate air compressor that can hold the working pressure for the whole cure. New to the workflow? Walk through it step by step in our how to use a pressure pot for resin casting guide, and compare chamber sizes in the best pressure pot for resin roundup.
Pressure pot vs vacuum chamber: hiding air vs removing air
These two tools are constantly confused, but they do opposite things. A pressure pot hides bubbles by compressing the air until it disappears, then curing around it. A vacuum chamber removes bubbles by pulling roughly -29 inHg (about -75 cmHg) to expand the air until it rises and bursts, physically pulling it out of liquid resin or silicone before you pour.
Which to use? Vacuum is best for degassing silicone molds and slow-cure liquids before the pour. Pressure is best for actually curing castings, because a pot pressurizes faster than a chamber can pull a full vacuum, and many fast-cure resins would gel before the chamber finished evacuating. Plenty of pros do both: vacuum-degas the silicone, then pressure-cure the resin. The full breakdown lives in pressure pot vs vacuum chamber for resin.
Butane vs propane torch: which to buy first
If you are choosing a torch fuel, the practical differences are about flame size and combustion, not temperature. Butane and propane burn at essentially the same flame temperature. Butane produces CO2 (cleaner, more precise, beginner-friendly) and suits small art pieces and detail work. Propane produces some CO and demands ventilation, but gives a larger, more intense flame that covers big tabletops and river tables far faster. For a single do-everything torch on larger work, a propane/MAP-Pro head like the TS8000 is the stronger first buy; for delicate jewelry-scale pieces, a small butane torch is gentler and harder to over-cook with.
Prevention beats removal
Every tool above is damage control. The bubbles you never create are free:
- Temperature. Keep resin and room at 70-80 F. Warm the bottles in a 75-80 F water bath for several minutes before mixing; this alone, combined with slow mixing for 4-6 minutes, can eliminate well over 90% of bubbles before you ever pour.
- Mix slowly. No whipping. Scrape sides and bottom, fold rather than beat.
- Layer deep pours. Pour in ~2 in (5 cm) lifts to control the exotherm and let trapped air escape. Deep-pour epoxies typically demold in about 24-72 hours per the manufacturer’s instructions.
- Seal porous surfaces with a thin coat first to stop off-gassing.
What you cannot fix: bubbles in cured resin
Be honest with yourself here: once epoxy is fully cured, bubbles trapped deep inside cannot be removed. They cannot be melted out, floated up, or pressurized away; the resin is solid. Your only realistic remedies are to sand the surface and re-pour a fresh top coat to hide surface flaws, or accept the piece. That permanence is exactly why prevention and the right tool at pour time matter so much. Catch surface bubbles with heat in the first few minutes while the resin is still wet, because that window closes the moment it gels.
The spec comparison
The comparison table above lays out all three recommended tools (plus the vacuum-chamber alternative) side by side: which bubbles each one fixes, the key spec, how to use it, the main risk, and the price band. The individual spec sheets below each tool break the numbers down further.
A note on fumes and safety
Two safety items are worth taking seriously. First, ventilation and a respirator: epoxy fumes and the combustion byproducts of a propane torch (which produces CO) both call for cross-ventilation and, for extended sessions, an organic-vapor respirator rather than a dust mask. Our resin safety and respirators guide covers the right cartridge type. Second, open flame: a torch near alcohol inks, solvents, or flammable molds is a genuine fire hazard, which is the main reason a flame-free heat gun is the safer default for beginners. Treat these as conservative minimums, not optional extras.