Your vac. pump will work if the area you are trying to vacuum is not
to large. Obviously it would pull enough vacuum on any amount of space
but with investing and casting there are time limits. If your area is
too large you will need a larger vac. pump to create the needed
amount of vacuum in the proper time frame. Another consideration is
that with a more powerful vac. pump you will get better movement
through the investment in the flask during casting.
For Vac. casting you are not looking to get 29.7 in of mercury. If
you attain this you have a problem. You should not get a real high vac
reading when you have the flask under vac. Once you pour the metal the
vac should be higher but still not a full vac. As for what a full
vacuum is: that depends on your altitude. 29 in vac can only be
reached at sea level if you are not at sea level your full vac. will
be different. The reason you should not be able to pull a full vac.
on a flask even after it has been cast is that the investment is
porus. so it should be able to pull air through it even after the
metal is poured. However, you should see very close to a full vacuum
on your guage after you have poured the metal.
The guage you need is a vacuum guage. We have those for $8.37 for a
standard gauge or $36.00 for a liquid filled gauge.
You can reach us toll free at 1-877-262-2196 or email at
If I can be of any more help let me know.