Miniature Bronze Figurines by Randall Zadar
Ancient Lost Wax Casting Process Used to Create Fine Art Bronze Miniatures
The process used to create Zadar Miniatures is the same process used to create bronze sculptures found in museums around the world. The process involves creating a master of wax, then encasing it in a plaster type material and burning (or melting) the wax out so that it becomes “lost.” The empty cavity is then filled with molten bronze creating the miniature figurine.
1.Starting with a special wax, the master design is sculpted. The sculpting time takes many hours to complete. Special tools are used to sculpt and hold the fragile wax. An amazing amount of detail can be achieved in the miniature wax sculpture, which is less than one inch in size.
Sculpting The Master Out of Wax
2. A mold is made and additional was patterns are produced exactly like the master. The wax patterns are placed in a flask and then encased in a plaster type material called Investment. The flasks are slowly heated in an oven for 12 hours. The wax melts out and the flasks reach a maximum of 1350 degrees. This is called the ‘burn out’.
Wax Patterns Placed in an Oven and Heated to Melt Out The Wax
3. The wax formed a perfect negative impression of the sculpture in the Investment material and then melted out. The cavity is now filled by heating bronze until molten with a torch and forced into the cavity with a centrifugal casting machine. The casting is quenched in water to cool. The new bronze casting is thoroughly cleaned.
The Bronze is Meted and Cast using Centrifugal Force Creating the Figurine
4. The bronze figurine is now inspected and mold lines removed. Each figurine is then sandblasted and prepared for paint. A white base coat is carefully sprayed. Custom colors are selected for each piece and the painting procedure begins. After the piece is completely painted and dry, it is varnished, numbered, signed and boxed. The miniature figurine is now ready for the collector.
The Bronze Figurine is Hand Painted Completing the Process
A more detailed explanation of the process is below
Miniature sculptures start out with an idea, a picture, some tools and sculpting wax. It can take 50 to 200 hours to sculpt a master.
The Finished Wax Master is placed in a mold frame.
An RTV mold material is mixed and poured into the frame around the master.
The RTV mold is carefully cut open and additional wax patterns can be made.
The wax master (on left) is destroyed in the molding process, but if the mold works properly, a perfect copy of the master is made (on right.)
One of the wax patterns from the RTV mold is cast into sterling silver. This now becomes the sterling master for the entire edition.
The production mold is now made from the sterling master. Pieces of mold rubber are placed around the master in the frame.
Packing the production mold with rubber.
The uncured production mold is placed in a vulanizer and using heat and pressure, cures the mold.
Curing the production mold for 40 minutes at 350 degrees.
The cured rubber mold is cut open using surgical knives (very sharp.)
Stretching the rubber to make the precision cuts.
The completed production mold sometimes has many pieces.
The production mold is injected with molten wax under pressure that fills the mold.
The process is repeated until enough wax patterns are produced.
Getting ready to do a full cast.
Each wax pattern group is first dipped in a solution that reduces air bubbles.
Investment powder is carefully weighed.
The investment powder is added to water.
Mixing by hand first.
A power mixer is used for smooth mix.
The investment is carefully poured into the flasks containing the wax patterns.
The flasks are vacuumed to remove all of the air.
After two hours, the investment has hardened and the bases are removed from the flasks.
Using a kiln that heats to 1350 degrees, the flasks are placed inside to begin the burnout process.
The flasks are placed inside the kiln and slowly heated to 1350 degrees. The wax slowly melts out and becomes “lost” this produces the negative cavity for the bronze to enter. The burnout process takes 12 to 14 hours.
The flasks are placed one at a time in a centrifugal casting machine and bronze is heated to 1850 degress.
When the bronze melts, the machine is released and it spins the molten bronze with centrifugal force into the cavity in the flasks.
The hot flasks are removed from the casting machine and quenched in cool water. This makes the bronze strong and helps break off the investment. This is a very violent reaction.
The new bronze casting is cleaned.
The investment material is packed around the casting and must be removed.
Using a pressure washer, the investment material is removed from the bronze casting.
The new bronze castings.
The Lost Wax Casting Process has many failures and rejects. The bronze can be reused but not the wax.
Each bronze casting is sand blasted to remove firescale and inperfections.
The bronzes are cleaned.
Grinding the bases flat
The bronzes with bases ground.
Imperfections and mold lines are removed with a diamond bur and a rotarty tool.
The bronzes are mounted onto a painting stick
Each bronze figurine is airbrushed white with a special paint.
Carefully airbrushing the figurines white
The bronzes are allowed to dry.
Custom colors are mixed for each painting step.
Each figurine is painted one step at a time. Some requiring 40 to 50 painting steps.
The flowers are carefully painted.
Some figurines have very complex painting steps taking several weeks to complete.
A completed tray of painted figurines.
The completed figurines are removed from the painting sticks, the bottoms are cleaned and painted.
The bottom is signed in the studio.
A label is placed on the box and the figurine is placed inside.
The finished bronze figurine is boxed and ready for the collector.
Thanks for looking.