Vacuum casting seal problem

The perforated flasks may cast more but I can only load four large
perforated flasks compared to six or seven large non perforated
one in my larger oven at one time. Small flasks also will fit next
to the large plain ones with more ability to stack. 

Yes, agreed relative to the cost of flask. . . especially if you
go to muffler shops for cars/semi-trucks and purchase a length of
exhaust pipe for your flask. . . don’t for get to measure your old
flask for size!!!

Jimc