WORKING IN THE CORTONA BRONZE FOUNDRY
images from the Fall Semesters of 2001, 2003
Sculpture students in the Cortona sculpture bronze foundry area use the lost wax         investment process - a traditional process that has been used for thousands of years.
The sprued wax model is enclosed in chicken-wire that will reinforce the poured investment material.



  On the left Sarah is shown
  mixing plaster to complete
   the flask. 


  The flask is the temporary container
  made around the wax model that will
  contain the investment material.
The form is first modeled in clay or wax.  If the form is modeled in wax and the modeled form is no thicker than one to one-and-a-half inches at any point, the process is fairly simple because the solid wax model is cast into a solid piece of bronze.
After the wax model is completed, it is attached to
the sprue and vent system.
The sprue and vent system are wax rods (or sometimes plastic straws) that will become the 'plumbing'  through which the molten metal will fill the mold.    
The plaster seals the joint between the tarpaper and the plywood. Inside the flask is a layer of chicken-wire for reinforcement.
These flasks are made of tarpaper, taped into a roll, with a plywood base.
In this flask Sarah has a sprue system  (the red wax) that holds two models (brown wax). 
The yellow and green plastic drinking straws are used as part of  the vents within the sprue system.

Each batch of investment is mixed in 5-gallon buckets, and must be added to the flask before the previous one sets up.
The average size flask, like this one, takes about five batches of investment to fill it.
      The investment is a mixture of plaster, brick dust,
       luto (re-claimed investment material), and water.

Ynette, shown at right and below, is sifting the 
crushed luto with the other dry materials. 

Dustin is pouring this investment
mixture into the flask.
                   note Ynette's proper investment-mixing attire               
of pearl necklace and earrings . . .                    
When the flask is filled and the investment has set-up completely (at least several hours), the flask is removed from the investment.
Don Dougan  -  sculptor
                          www.dondougan.com