BOOTHILL BRONZE WORKS

LOST WAX CERAMIC SHELL BRONZE CASTING

       Cast bronze Cremation Urns - Keepsake urns - Bronze Wind Bells

Studio of Douglas Covert

A Fine Arts Bronze Foundry

        THE ANCIENT ART OF LOST WAX CASTING

4,000 YEARS AGO 2,000 BC

SOMEWHERE BETWEEN THE BLACK SEA AND PERSIAN GULF, AN ARTIST CRAFTED A VISION IN BEESWAX COVERED IT IN LIQUID CLAY AND BAKED IT IN A FIRE.  IN THE FLAMES THE WAX WAS LOST, REPLACED BY EMPTY SPACE. TIN AND COPPER-ALLOYS OF BRONZE- WERE GATHERED AND HEATED.  THE MOLTEN METAL WAS POURED INTO THE CAVITY OF THE FIRE HARDENED CLAY.  THE METAL COOLED AND THE ARTIST KNOCKED OUT THE CLAY FROM THE METAL.  ELEMENTS OF THE "LOST WAX" PROCESS HAVE BEEN REFINED, BUT BRONZE CASTING IS ESSENTIALLY THE SAME AS IT WAS IN 2,000 B.C. DURING THE AKKADIAN PERIOD.

THE SILICONE RUBBER MOLD

1. 1/2 OF THE SCULPTURE IS NESTLED INTO A BASE OF CLAY THE OTHER EXPOSED 1/2 IS PAINTED WITH SILICONE RUBBER AND BACKED WITH PLASTER. 2.  THE MOLD IS THEN FLIPPED OVER AND THE CLAY REMOVED AND PAINTED WITH SILICONE RUBBER AND PLASTER BACKED.  THIS GIVES YOU A MOLD THAT IS THE EXACT NEGATIVE IMAGE OF THE ORIGINAL SCULPTURE. 3.  THE MOTHER MOLD IS NOW READY FOR REPRODUCTION OF THE ORIGINAL PIECE.

 WAX SLUSHING AND GATING

4.THE MOTHER MOLD IS THEN STRAPPED TOGETHER.  5.215 DEGREE WAX IS POURED INTO THE RUBBER MOTHER MOLD AND SLUSHED AROUND EVENLY UNTIL A WALL THICKNESS OF 3/16TH ON AN INCH.  6.  THEN A DOWNSRU, GATES AND VENTS ARE ADDED.  THE DOWNSPRU IS WHERE THE METAL WILL ENTER THE MOLD AND FLOW TO THE GATES THAT ARE CONNECTED TO THE SCULPTURE.  THE VENTS AT THE TOP OF THE PIECE ALLOW THE GASES AND METAL TO ESCAPE THE MOLD.  

CERAMIC SHELL

7.  THE GATED WAX SCULPTURE IS DIPPED INTO A LIQUID CERAMIC SLURRY.  8. WHILE THE PIECE IS STILL WET WITH THE SLURRY IT IS COVERED WITH A FINE PURE SILICA SAND. THERE WILL BE 3 COATS OF FINE GRADE SAND, 3 COATS OF MEDIUM GRADE SAND AND 3 TO 5 COATS COARSE GRADE SAND. 9.  A SHELL DRYING. EACH COAT MUST DRY FOR ABOUT THREE HOURS BEFORE THE NEXT COAT CAN BE APPLIED.

THE WAX BURNOUT

10.  THE BURNOUT KILN IS HEATED TO 2,000 DEGREES.  11. THE DRY CERAMIC SHELL IS LOADED INTO THE KILN UPSIDE DOWN SO ALL THE WAX WILL MELT OUT LEAVING EMPTY SPACE THE SHAPE OF THE SCULPTURE.. THE SHELL IS LEFT IN THE KILN FOR ABOUT 1 HOUR AT 1650 DEGREES.  THE SHELL TURNS TO CERAMIC AT THIS POINT IT IS READY FOR THE MOLTEN BRONZE.  12. WHEN THE BRONZE IS READY THE HOT SHELL IS REMOVED FROM THE BURNOUT KILN AND PLACED IN A SAND PIT.

THE BRONZE POUR

  WEDNESDAY APRIL 7TH 2005 2,200 DEGREE RED HOT BRONZE MAMMA

13.  90 LBS OF BRONZE IS PULLED FROM THE FURNACE AT 2200 DEGREES.  14. THE CRUCIBLE IS PLACED IN A 2 MAN POURING SHANK.  15. THE MOLTEN BRONZE IS PORED INTO THE SHELL.

DEVESTING THE SHELL       SANDBLASTING     GRINDING

16. WHEN THE METAL COOLS THE CERAMIC SHELL IS KNOCKED AWAY FROM THE PIECE.  17. THE REST OF THE SHELL IS THEN SANDBLASTED OFF.  18.THE DOWNESPRU, GATES AND VENTS THEN ARE GROUND OFF THE PIECE.

PATINA      POLISHING      FINISHED PIECE

19. NITRIC ACID PATINAS ARE HEATED INTO THE PIECE.   20. THE PIECE IS THE POLISHED ON BUFFING WHEELS AND A WAX IS HAND BUFFED INTO THE PIECE.  21. THE FINISHED PIECE.