BRONZE CASTING PROCEDURE




ARMATURE CONSTRUCTION
   Basic construction of the armature is wood and foam.
Wire and metal foil is added
to insure that clay bonds well
to the surface.
 
  Armature is covered with
Non Sulphurated Plasteline.



MODEL DEVELOPMENT
 
Various approaches are tested to
establish the style of the piece
and to achieve the likeness and
character of the subject.
 
 



MOLD MAKING (front)
  Model is divided into front and back halves with thin metal shims.
Clay dam is built to
contain mold material.
Several layers of flexible urethane
rubber are applied to model surface to a uniform thickness.
 
  Plaster " Mother Mold " is used to
hold the flexible urethane
mold form in place.



MOLD MAKING (back)
 
  Process used in making the
front mold is repeated for
the back half.
 



BUILDING WAX POSITIVE
  Molten wax is applied to the inside of the urethane mold with
a natural bristle brush.
Many layers of wax are slowly built to assure uniform thickness
of approximately ¼ ".
 
  Back section is built to same
uniform thickness.
Wax is released from mold after
sufficient cure time to prevent
warpage.
 
  Front and back sections are joined
together with molten wax and joint
seams are " chased " to appear seamless.



CERAMIC MOLD
  Sprue and vent systems of wax are attached to the wax model by which the heated wax will later flow from the mold and the molten bronze will enter, then the dipping process begins.
The wax model is coated with a
refractory ceramic material then
coated with sand.
 
  The refractory-sand process is repeated several times over a period of days under constant
temperature and humidity requirements until a desired thickness is reached.
After the shell is thoroughly
cured the piece is placed in
a kiln for hours to remove
any moisture and eliminate the
wax creating a positive void in
which will be poured the
molten bronze.
 



CASTING
  The heated ceramic shell is placed into a steel container and held in place with sand.
Molten bronze of approximately
2,200 F is prepared for the pour.
 
  Pouring molten bronze is
a team effort.
The cast piece remains in sand
allowing the bronze to solidify
and the molecules to align in a
certain matrix.
 



SHELL REMOVAL
  The ceramic shell is carefully removed so as not to
damage the bronze.
As much shell is removed
by hand as possible.
 
  Air tools are employed
in interior areas.
Sprue systems and vents
are removed with carbon
abrasive cut-off wheels.
 



BEAD BLASTING
  100 mesh silica under 100 lb.
Air pressure is used to
remove remaining shell.
 



METAL CHASING
  All final remains of the sprue
feeder system is removed.
TIG welding utilizing bronze
rod eliminates any imperfections.
 
  Separately cast pieces attached with the use of the TIG welder and bronze rod.
Metal is "chased" ... ground filed
and sanded.
 
  After chasing process the entire sculpture is again bead blasted to create a uniform surface.



PATINA PROCESS
  Bronze is heated to a uniform temperature of approximately
350 F and a chemical solution
is applied in light successive
layers to achieve desired color.
When the bronze has reached
the right color and has sufficiently cooled the waxing process begins.
 
  Half a dozen coats of
wax is applied to
assure surface protection.
 
 
"Mega contemplating a bust of Camargo"
after... Rembrandt van Rijn.
"Aristotle contemplating a bust of Homer"