I have today mixed and poured my first mould. Whilst degassing small (100 gram) mixes the rubber certainly bubbled up but I did not notice any significant 'collapse' as shown on your tutorial video, even after approximately 5 minutes.

The degassing chamber negative pressure was in excess of 0.8 bar. I left the pump running and chamber outlet valve open during this period.

Any reason I did not notice a collapse and is that negative pressure ok?

Regards

Ray