Building a vacuum assisted caster for silver and gold.

Thank you guys for all your input on this subject. Hopefully I can get this little project to work so I can share helpful information with anyone that's interested.

Debby, I'm using a vacuum cavity to fit the perforated flasks used for vacuum casting. This allows for the vacuum to pull on the investment from all sides, allowing the flow of the molten metal to fill every little recess in the mould perfectly. I've been doing a lot of research on the subject, and it appears that when you use a vacuum caster that only pulls on the flask from the base, that it doesn't fill the horizontal cavities in the plaster very well.

I've been reading that centrifugal casting has a higher initial fill temperature, which helps it all solidify more homogeneously, but that vacuum assisted casting fills the moulds more precisely than any other form of casting when using the perforated flasks.

I found some of these silicon gaskets for real cheap on eBay. They have a notably lower max temperature than the casting temperature for the both silver and gold, so like Debby said, they will deteriorate with use. Apparently they also make graphite gaskets to use in combination with the red silicon gaskets and this really extends the life of the silicon since graphite is such a poor thermal conductor.

I'll be ordering parts today and tomorrow and hitting the Home Depo for some extra fittings and such and I'll share my progress with you guys as I go along. Again, thanks for all your input, guys.