How to Get Bubbles Out of Small Resin Molds Without a Pressure Pot
If you’re casting small resin pieces—charms, mini figurines, keychains, earrings, trays—you’ve probably felt this frustration: you demold something that looks almost perfect… and then you spot it. A bubble on the cheek. A tiny void in a corner. A pockmark right on the front.
A pressure pot is one solution, but it’s not the only one—and it’s not always the right fit. Whether you don’t want the extra equipment, don’t have the space, or you simply prefer a simpler setup, you can still get clean, professional-looking casts.
This guide walks you through 10 practical, repeatable ways to reduce or eliminate bubbles in small resin molds—especially the stubborn ones that hide in tight details.
Quick CTA: If you’re building a small-mold workflow, start with molds designed for crisp detail and easier release—browse Fynzio’s collection here: https://fynzio.com/collections/resin-molds
Why bubbles happen in small molds (and why they’re so annoying)
Small molds are bubble magnets for two big reasons: surface tension makes microbubbles cling to silicone walls, and trapped air pockets form in undercuts and details—think eyebrows, lips, corners, textured patterns, thin limbs, or lettering.
Even if your resin mix looks clear in the cup, air can still get trapped during the pour, especially when resin bridges over a detail and seals air underneath.
The 10 best ways to remove bubbles (no pressure pot)
1) Tilt + Tap (the fastest win for detail bubbles)
Pour resin to about 80–90% full (leave headroom). Tilt the mold so the trapped-detail area becomes the high point, then tap the mold with your fingers or gently against the table. Rotate and repeat until you see bubbles rise.
Pro tip: For ultra-small cavities, cover the opening with your palm while tapping to prevent spills.
2) Add gentle vibration (a “poor man’s pressure pot”)
Vibration helps bubbles detach from surfaces and float upward. Options include a small handheld massager used on the table, an electric toothbrush pressed against the mold edge, or a low-power vibrating tool. Vibrate after pouring, then again a few minutes later.
3) Powder your molds to reduce surface bubbles
A light dusting of cornstarch, arrowroot powder, or unscented baby powder can reduce surface tension so bubbles don’t stick. Dust lightly with a soft brush and tap out excess. Avoid breathing powders.
4) “Pre-rest” your resin
If your resin system instructions require shaking a component, do it ahead of time, then let bottles sit so microbubbles can rise out before you mix and pour.
5) Use a thin-stream (high) pour
Pour slowly in a thin ribbon into one spot and let resin flow outward. A thin stream can stretch and pop some bubbles on the way down.
6) Pour through a mesh screen
A clean fine mesh can break bubbles as resin passes through. Pour slowly to avoid foaming.
7) Massage detail zones (finger + toothpick)
Use a gloved fingertip to massage resin into details on open molds. Use a toothpick to trace edges, poke corners, and guide bubbles upward.
8) Coat-first, fill-second
Add a small amount of resin and rotate/tilt to coat details first, then fill the mold fully. This prevents resin from bridging over details and trapping air beneath.
9) Inject resin with a syringe
For narrow cavities (thin arms/legs/channels), inject slowly from the lowest point upward so air can escape ahead of the resin.
10) Add vents so air has somewhere to go
If bubbles repeat in the same spot, add a vent path. Cut a small V-notch at the edge, or punch a clean vent hole with a small tube. Place vents where trimming and sanding are easy to hide.
A simple “no-pressure-pot” bubble-free workflow
- Lightly powder the mold
- Coat-first, fill-second pour
- Tilt + tap for 30–60 seconds
- Gentle vibration for 10–20 seconds
- Toothpick-check corners and lettering
- Re-tap 3 minutes later
Troubleshooting: what your bubbles are telling you
Bubbles only on the surface
- Use powder + vibration
- Pour slower in a thinner stream
- Clean the mold (dust and residue can grab bubbles)
Bubbles only in one detail area
- Use coat-first + toothpick
- If it repeats, add a vent
Microbubbles in the cup
- Mix slower (stir, don’t whip)
- Let resin rest briefly before pouring if pot life allows
Safety basics (quick but important)
Increase ventilation and follow label/SDS guidance when using epoxies and resins. Wear gloves and avoid repeated skin contact.
Mid-article CTA: Need help calculating how much resin to mix so you don’t overwork a big batch (which increases bubbles)? Use the calculator: https://fynzio.com/pages/resin-calculator
Final checklist: bubble-free small molds
- Mold lightly powdered
- Resin mixed slowly
- Coat-first, fill-second for detailed areas
- Tilt + tap immediately after filling
- Gentle vibration in short bursts
- Toothpick corners and undercuts
- Add vents if one spot repeatedly traps air
- Re-check and tap again after a few minutes
Wrap-up: you don’t need a pressure pot—you need a system
These methods prevent, release, and route bubbles out of the mold. Once you build a repeatable workflow, your casts get cleaner fast—and you spend far less time patching pinholes.
End CTA: Explore molds designed for crisp detail and easy cleanup: https://fynzio.com/collections/best-sellers and see what’s new: https://fynzio.com/collections/new-arrivals
About the Author
Written by the Fynzio team—makers who test molds and casting workflows with real-world resin projects to help DIY creators craft cleaner details, smoother surfaces, and more reliable releases.
Last updated: December 29, 2025
0 comments