The investments are set into the kiln with the open end down, so the wax will run out as it melts.
View of the kiln as it is being unloaded the next morning.
The molds are set on blocks and slightly away from each other to leave a convection-space within the kiln.
When all the investments for the class are completed, they are loaded into the burnout kiln, as Jon is doing here.
The kiln is a simple stacked-brick construction, and Beth, Jess, Winter, and Kate are shown below re-stacking the outer layer of the front wall of the kiln with bricks while Ehryn watches.
When the wall is complete, the partially visible lid (upper left) is lowered onto the walls of the kiln.  The lid is made of heat resistant insulation fitted into a stainless steel framework.
Three large gas burners are then ignighted and the temperature is raised slowly for about twelve hours until the wax melts and burns out of the investments. 

This is the "lost wax" from which the name of the process is derived.
The temperature is then allowed to rise slowly up to about 1000°F to completely burn-off any organic material or water in the mold.  The temperature is held for 24 hours, and then burners are shut off.

The morning after the kiln is shut down the investment molds are unloaded while the molds are hot.  The kiln temperature is 300° F or more, and the molds weigh about half as much as they weighed before they were put into the kiln.
Don Dougan  -  sculptor
burnout kiln