How do I remove bubbles during transformer resin potting?

Why Bubbles Occur in Resin Potting

Bubbles typically form when air becomes trapped as resin is poured over or around the transformer. This can happen if the resin is poured too quickly or from too high, allowing air pockets to form and get trapped inside the mould or around windings. Ensuring a calm, controlled process greatly reduces bubble formation.

Best Techniques to Eliminate Bubbles

• Pour Slowly and Steadily: Pouring the resin in a gentle, continuous stream from one side allows air to escape as the resin fills the cavity.
• Tap the Mould Gently: Lightly tapping or vibrating the mould after pouring encourages bubbles to rise to the surface, making them easier to remove.
• Remove Surface Bubbles with Heat: After pouring, pass a heat gun or torch carefully over the resin’s surface. This helps pop surface bubbles before the resin begins curing. Take care not to overheat, as this could cause the resin to cure unevenly or warp.

Practical Resin Choices and Tips

Selecting the right resin is important for achieving a bubble-free result, particularly in projects of different thicknesses. For layers up to 2cm thick, a clear epoxy like “Trasparente” multipurpose epoxy resin offers self-levelling properties that assist in bubble release. For larger potting jobs or deeper casts, consider options such as EpoxyTable 5-Five or Epoxytable 10-Ten for pours between 2–10cm. Always follow recommended pour depths to minimise the risk of overheating or trapping air.