I hope this gives some insight. and this just the way I see it…
Solid wall flask for spin cast. the vacuum only does the first 1 to
2 ins. unless you use some type of webbing.
If you having surface issues from Craving wax. I would use pref.
If you using plastic with metal molds. again Pref. Flask…
If there is anything else just ask. Have a stullerific day
Andy “The Tool Guy” Kroungold