I have made a vacuum forming table, and it works well, but with the PVC (0.38mm, clear rigid sheet) it cools too quickly and only forms the top half of the master and is room temp within seconds.

The recommended forming temperature was 130C. There was sag in the PVC before I moulded, but perhaps not enough. I also did some more research on the temp ranges for PVC, and found that 115-130C was elastic, 160C plastic and at 180C degrades. Do I want the PVC to be in a "plastic" state for forming or elastic state? I am thinking I need to raise the heat to 160? But I of course do not want to find out the hard way that it might fall apart or release chemicals at the plastic stage - so I thought I would ask.

Also, has anyone tried to vacuum form flexible Vinyl? I think it would make really great flexible moulds, but I am not sure if it is safe to heat and will melt or form. I imagine would need the same temps as rigid PVC.

Thanks for your help!