Making a Refined Giant LED - Part 5 - Silicone Mold for the Bulb

After sealing the mold box edges with PVA wood glue and placed the master mold in the box. I mixed and vacuum degassed a batch of platinum silicone. It was very thick and I filled the mold about halfway, then degassed the mold; then filled the rest of the mold and degassed again. Excess silicone did spill over the edges, but I wiped most of it away. The pot life of the silicone was 90 minutes and the cure time was 12 hours.

After letting the silicone cure for the correct time over night. I began to try and soften the PVA by soaking the mold in water, and carefully prying the mold box apart. I had to use more force than I liked and would redesign the box and try to use wax to seal the joints in the future.

I also made a quick cast using Smooth Cast 200 crystal clear resin, I wanted an example to show at the Carnival of Science – Cork (

I'll be attending the Wear It Innovation Submit ( so I'm not sure when the next video will be released.


Prusa3D i3 MK3 (

Affiliate Links:
Polycraft Silastic T4 Translucent Silicone Shore A40 550g Kit Mould Making Rubber - (Amazon UK) -
Polycraft 600g Yellow Wax Fillet Block for Mould & Patterns - (Amazon UK) -

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