drat drat & double drat

[Lisa Quinn]

Interesting, do you know the name of the company your college used?

I would be interested in this info too if you have it available !!

[Emerald]

there are lots of metal casters in the jewellery quarter x

[Matp85]

ok aint been on the forum for a loooong time but since i use investment powder nearly every day with a vacuum pump and cast every week i can assure you a vacuum pump IS needed.

As someone stated it does take take most excess air out the mixture and reduces the size/content of the air, which forms in bubbles from the surface of the wax to ensure a more smoother finish. This allows a better finished peice with no airholes.

centrifuge (don't knock it, it was how it used to be done) was the old style casting my boss used to use that and although it could be a nightmare it was still achievable and some platinum caster use this method to this day.

We have delft clay but is only good for heavy peices and chunky items. For smaller more defined peices a good casting machine is needed or use a company. I use a mc15 casting machine which is both negative and postive pressured for a good cast.

let me know if you need any help or advice as its over christmas and my busy time is over will be more active and hope to get to know everyone better!

[Dennis]

Here is my contribution: The investment is a dedicated product that will not crack on heating and expands when heated to compensate for the shrinkage of the molten metal as it cools. It is normally contained in a steel ring with a liner and the object to be burnt out is at the centre.When casting, the investment is brought up to a temperature similar to that of the molten metal.
Improvisation is not recommended because of the danger of exploding investment and molten metal.
Dennis.