This is a tin can with a light bulb at the top to create heat.

It has a 4" hole cut in the top to let  the heat out.  It also doubles as my dop wax heater.  I use a 4 inch tobacco tin to put the wax in.

This is my investment wax setup with a very good vacuum pump that will draw down to -30 inches of Hg.(Mercury).

Emeralds in Vacuum chamber.

Whole setup ready to go.

First indication of bubbles being pulled out of the Emerald rough.  This starts at -20 inches of Hg.

Going Strong...this keeps up for approximately 3 hours.  As long as there is any air in the Emerald, it wont reach -30 inches of Hg.  We let it run overnight and by morning, there were only miniscule bubbles coming out and the pressure had dropped to -29.5 inches of Hg.

Really starting to bubble.

Looks like its actually boiling.

Boiling

Close up of the action.

Foam on the top from the boiling.