Free shipping on orders over £29,85 
Shipping Tracking! 
Google
Facebook← Back to How to get soft resin to mold?
Trapped air bubbles are a common frustration when working with soft resin. Without the right techniques, these bubbles can compromise the finish and detail of your moulded piece. Addressing this issue is essential for achieving flawless results in your resin projects.
Why Do Air Bubbles Appear in Soft Resin?
Air bubbles can appear during the mixing and pouring stages, often as a result of vigorous stirring or pouring too quickly. The viscosity of many soft resins makes them prone to trapping air, which then rises to the surface slowly—or gets entirely stuck—especially in detailed or deep moulds.
- Poor mixing methods
- Rapid pouring or agitation
- Mould design with undercuts traps air
Practical Tips to Minimise Trapped Bubbles
Start by mixing your resin or silicone rubber slowly and thoroughly, ensuring even incorporation of activator or hardener while minimising agitation. When ready to pour, do so in a thin stream, allowing the mixture to gently fill the lowest recesses first. Tapping the mould lightly can encourage trapped bubbles to rise.
If available, use a pressure chamber or pressure pot after pouring. This will compress and reduce bubble size, leading to noticeably clearer and more detailed moulds. For small or intricate pieces, consider products such as the “Liquid Mould” – Casting Liquid Silicone Rubber, which is designed to flow into fine details and can benefit from pressure casting for optimal clarity.
When This Matters Most
Bubbles have the biggest impact when creating items with intricate details, transparent finishes, or objects that must precisely fit together. If you are working on jewellery, artistic pieces, or keepsakes, addressing bubbles early is especially critical to maintain professional quality.
Related products
Related guides
Taking steps to prevent trapped air bubbles will dramatically improve your results with soft resin moulding. For further guidance on creating high-quality resin pieces, see our full guide on how to get soft resin to mold.