Thread: clear casting epoxy scales

Can I heat silicon or PU pouring rubber to remove bubbles?

I have tried putting the mixtures in a glass jar with a metal cap that has a valve screwed in and suck out the air with an inversed soccerball/bicycle pump. This does create a decent vacuum but not strong enough to get rid off all the tiny bubbles.

Originally Posted by Piet

Can I heat silicon or PU pouring rubber to remove bubbles?

I have tried putting the mixtures in a glass jar with a metal cap that has a valve screwed in and suck out the air with an inversed soccerball/bicycle pump. This does create a decent vacuum but not strong enough to get rid off all the tiny bubbles.

I haven't tried that. I do get preey good results with placing the item to make the mould from on a small piece of flat glass and buiding up a dam around it with plasticene or small glass slips with the modelling clay holding them down and sealing the corners, then brushing a thin cot of the silicon onto the item to be moulded.

The set time is long enough to let you brush any bubbles that you can see out of the way before gently pouring the rest of the silicon into the chamber.

If any bubbles have formed, the holes in the hardened silicon mould can be plugged with modelling clay, or the projections can be sanded off the finished cast item.

Regards,
Neil