How to Remove Bubbles in Thick Resin Casts

Q: Practical Techniques for Bubble Removal

Slow Pouring: After thoroughly mixing your resin, pour it gently into the mould in a steady, slow stream. This minimises the introduction of new bubbles. Tapping the Mould: Immediately after pouring, tap or gently shake the sides of the mould. This helps move any bubbles upwards where they can release themselves. Surface Heat: Use a heat gun or torch lightly over the surface right after pouring. A gentle pass of heat pops surface bubbles, but avoid holding the heat too long in one place to prevent overheating. For deep castings, choosing the right resin for the job is crucial. For example, “Epoxytable 10-Ten” Deep Pour Epoxy Resin is specially formulated for thick castings. Its low viscosity helps bubbles escape more easily during the curing process.

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How Can I Remove Bubbles in Thick Resin Casts?

Trapped bubbles can be one of the biggest challenges when casting thick resin projects, such as large cubes or tabletops. Taking the right steps during the pouring and curing process leads to a beautifully clear and professional finish.

Why Do Bubbles Form in Deep Resin Casts?

Bubbles are often introduced while mixing resin and hardener, but they can also form from trapped air in the mould or from warmer temperatures causing expansion. The thicker the pour, the harder it is for these bubbles to rise to the surface and escape on their own, so they can become trapped deep inside your cured project.

Practical Techniques for Bubble Removal

Slow Pouring: After thoroughly mixing your resin, pour it gently into the mould in a steady, slow stream. This minimises the introduction of new bubbles.
Tapping the Mould: Immediately after pouring, tap or gently shake the sides of the mould. This helps move any bubbles upwards where they can release themselves.
Surface Heat: Use a heat gun or torch lightly over the surface right after pouring. A gentle pass of heat pops surface bubbles, but avoid holding the heat too long in one place to prevent overheating.

For deep castings, choosing the right resin for the job is crucial. For example, “Epoxytable 10-Ten” Deep Pour Epoxy Resin is specially formulated for thick castings. Its low viscosity helps bubbles escape more easily during the curing process.

When Does Bubble Control Matter Most?

Controlling bubbles is particularly important for large, clear resin projects where imperfections are highly visible, such as decorative cubes or tabletops. If you’re working on deeper pours—especially those between 5–10cm—taking extra care with your pouring and bubble-removal techniques is essential for achieving a flawless, glass-like appearance.

Related guides

How To Make A Mould For A Large Resin Cube

Mastering the removal of bubbles is a key part of creating impressive resin castings. For further tips and advice on making a mould for a large resin cube, explore our main guide on the subject.