I use a vacuum system and pour into flasks that are from 900 to
1200 degrees F. depending on the thickness of the wax patterns
and the metal being cast. I always use a perforated flask as this
insures that I will have optimal results. I definitely prefer
vacuum casting over centrifugal. If casting from a pad on top
doesn't work and casting with a perforated flask does, then I
think you have answered your own question. Obviously you are not
getting sufficient vacuum when you cast on a pad.
When using non perf flasks, do you add some sort of aid spacer
to the flask to assist in getting the air out. I use heated,
pinched closed with pliers, plastic straws down the side of the
flask where ever the piece being cast is close. Hold the straw
pieces in place with paper clips for placements and investing.
When the investment hardens, take off the paperclips and when
ready to heat the flasks, the straw burns out (sorry about the
bit of plastic, but ....) and this has worked very well for
us over the years. Perf flasks are great, but all of ours are
pretty big and a waste of material and all if not really needed.
Just another way to skin the same old cat!!!!
John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin' Wax Works. etc.
PO Bx 44, Philo
Ph 707-895-2635 FAX 707-895-9332
There is no limit to what you can achieve,
if you don't mind who gets the credit.