HUMANS HAVE BEEN CASTING METAL FOR THOUSANDS OF YEARS. METAL CASTING PROCESSES WERE INVENTED AND USED IN AFRICA, CHINA AND INDIA IN VERY ANCIENT TIMES. THE LOST WAX PROCESS, THE METHOD I USE, HAS BEEN HANDED DOWN TO US VIRTUALLY UNCHANGED FROM THE TECHNIQUES USED IN EARLY AFRICAN COMMUNITIES. IN AFRICA TODAY, BENIN METAL WORKERS STILL CAST USING ONLY THE MOST RUDIMENTARY EQUIPMENT, BEESWAX, CLAY AND FIRE. IT IS IMPOSSIBLE FOR ME TO REFLECT ON THEIR WORK WITHOUT CONSIDERING, THAT THE DEVELOPMENT OF METALLURGY HAS MADE POSSIBLE MUCH OF THE WAY OF LIFE WE KNOW TODAY.

THE LOST WAX PROCESS COMES TO US ESSENTIALLY UNCHANGED, BUT THE MATERIALS USED HAVE BEEN GREATLY IMPROVED. TODAY THERE ARE HUNDREDS OF TYPES OF WAXES, EACH WITH CHARACTERISTICS THAT MAKE IT UNIQUELY SUITED FOR A PARTICULAR MODELING/CASTING APPLICATION. THERE ARE ALSO HUNDREDS OF TYPES OF CLAY (CALLED "INVESTMENTS" IN INDUSTRY) FOR ENCAPSULATING THE WAX MODEL.

THE TYPE OF INVESTMENT IS SELECTED ACCORDING TO THE NEEDS OF THE CASTER, AS ARE THE METAL ALLOYS, OF WHICH COUNTLESS VARIETIES ARE AVAILABLE.

THE LOST WAX PROCESS IS AWE-INSPIRING, BUT NOT COMPLEX. ANY LIQUID, INCLUDING MOLTEN METAL, WILL TAKE THE FORM OR SHAPE OF THE VESSEL CONTAINING IT. WHEN WATER FREEZES INTO ICE, THE ICE ACHIEVES EXACTLY THE FEATURES OF THE VESSEL...THE ICE TRAY FOR EXAMPLE.. GELATIN AND JELLO TURNED OUT FROM THEIR MOLDS, ARE A FAMILIAR EXAMPLES..ALSO..METALS, HOWEVER, ARE FOR THE MOST PART SOLIDS AT ROOM TEMPERATURE. TO CAST THEM, WE MUST LIQUEFY THEM, AND THIS REQUIRES EXTREME HEAT. ALUMINUM, FOR EXAMPLE MELTS AT ABOUT 1000 F, SILVER AND GOLD AT ABOUT 1500 F, BRONZE AND BRASS AT ABOUT 2000 F AND STEEL AND IRON AT EVEN HIGHER TEMPERATURES. THE MELTING TEMPERATURE OF METALS VARY, DEPENDING ON THE TYPE OF METAL OR ALLOY. "ALLOYS" ARE MIXTURES OF METALS AND ARE MOST COMMONLY USED IN INDUSTRY. BRONZE AND BRASS ARE ALLOYS OF COPPER. BRONZE BEING A MIXTURE OF COPPER AND TIN AND BRASS A MIXTURE OF COPPER AND ZINC.

BOTH THE VESSEL IN WHICH THE METAL IS MELTED AND THE MOLD INTO WHICH THE METAL IN POURED MUST BE ABLE TO WITHSTAND EXTREME TEMPERATURE AND OFTEN THE SUBSTANTIAL WEIGHT OF THE METAL. EARLY CASTERS FASHIONED THE VESSEL OR "CRUCIBLE" FROM CLAY. THE CRUCIBLE, LADEN WITH METAL, WAS HEATED IN A FIRE UNTIL THE METAL BECAME MOLTEN, AND THEN IT WAS POURED INTO A MOLD ALSO MADE OF CLAY. IN AFRICA TODAY THE BENIN CASTERS STILL USE CLAY FROM THE RIVER BANKS TO ENCAPSULATE THEIR WAX MODELS (THIS TASK IS USUALLY DONE BY APPRENTICES), AND THE CAST AFTER THE MOLD IS BURNED OUT.

I USE A MODERN PROCESS CALLED "CERAMIC SHELL" CASTING., THIS PROCESS IS SIMPLE TO EXECUTE AND CREATES A WONDERFULLY DETAILED CASTING., THE CREATION OF THE MOLD IN THE "CERAMIC SHELL" METHOD IS VERY MUCH LIKE BREADING CHICKEN. WHEN CHICKEN IS BREADED, IT IS DIPPED FIRST INTO MILK OR A BATTER AND THE SPRINKLED WITH BREAD CRUMBS. IF THE WAX MODEL IS USED IN PLACE OF THE CHICKEN AND A SLURRY INSTEAD OF MILK OR BATTER, AND SAND INSTEAD OF BREAD CRUMB, WE WILL BE CREATING A "CERAMIC SHELL" MOLD.

WHAT IS A "SLURRY" ??? A SLURRY IS A MIXTURE OF VERY FINE SAND AND A LIQUID BINDER, USUALLY COLLOIDAL SILICA. SLURRY HAS A CONSISTENCY OF DAIRY CREAM, AND IT MUST BE CONSTANTLY STIRRED TO KEEP THE FINE SAND IN SUSPENSION. THE SLURRY IS THE ADHESIVE THAT HOLDS AND/OR CEMENTS THE COATS OF SAND TOGETHER TO FORM THE CERAMIC SHELL MOLD.

AN EXACT MODEL OF THE FORM TO BE CAST IS FIRST SHAPED IN WAX, INCLUDING ALL DESIRED DETAILS. THE WAX MODEL IS THEN "SHELLED" -ENCAPSULATED IN A CERAMIC SHELL MOLD. THIS IS DONE BY DIPPING THE PIECE IN A SLURRY AND THEN SPRINKLING IT WITH SAND. WHEN THE SLURRY AND SAND COAT DRIES, THE PROCESS IS REPEATED AT LEAST 8 TIMES. THE RESULT IS THE FORMATION OF A THICK CERAMIC SHELL MOLD AROUND THE WAX MODEL.

THE SHELLED MODEL IS THEN "BURNED OUT"--SUBJECTED TO INTENSE HEAT THAT MELTS AND BURNS THE WAX MODEL. AT THE SAME TIME, THE HEAT BAKES AND HARDENS THE PLASTER LIKE MATERIAL FORMING THE CERAMIC SHELL. AT THE END OF THE "BURN OUT" PROCESS, THE WAX MODEL HAS VANISHED, LEAVING A VOID IN THE PLASTER LIKE MATERIAL THAT IS THE EXACT DUPLICATE OF THE MODEL. THE BAKED SLURRY AND SAND COATS HAVE BECOME THE MOLD. THE LOSS OF THE WAX PROVIDES THE NAME FOR THIS PROCESS....."THE LOST WAX PROCESS"

TO THE WAX MODEL, PRIOR TO SHELLING, ARE AFFIXED PIECES OF WAX CALLED "SPRUES" AND A FUNNEL-LIKE STRUCTURE CALLED THE CUP. THE TUBE LIKE SPRUES ARE OF TWO TYPES, FEEDERS AND VENTS. THE FEEDER SPRUES FEED THE METAL INTO THE MOLD. THE VENT SPRUES ALLOW AIR IN THE MOLD TO ESCAPE, SO AS NOT TO IMPEDE THE FLOW OF METAL INTO THE MOLD. THE WHOLE NETWORK OF SPRUES AND CUP ARE SHELLED, SO THAT THEIR FORMS ARE PRESERVED IN THE MOLD.

THE CUP IS USUALLY ABOUT THE SIZE OF A PLASTIC COFFEE CUP. IN FACT, I USE A STYROFOAM COFFEE CUP TO FORM THE CUP. THE CUP IS ATTACHED TO A FEEDER, WHICH IN TURN IS ATTACHED TO THE WAX MODEL. THERE MAY BE MORE THAN ONE FEEDER AND/OR VENT ATTACHED TO THE CUP, DEPENDING ON THE COMPLEXITY OF THE CASTING. THE WEIGHT OF THE METAL IN THE CUP IS THE FORCE THAT PUSHES THE METAL INTO THE MOLD BY WAY OF THE FEEDERS AND AT THE SAME TIME PUSHES AIR OUT OF THE MOLD THROUGH THE VENTS. THE CUP AND SPRUES FORM A WEB LIKE STRUCTURE AROUND THE WAX MODEL. THIS CUP/SPRUE NETWORK IS SHELLED WITH THE WAX MODEL AND REMOVED FROM THE CASTING IN THE FINISHING PROCESS. AFTER THE MOLTEN METAL HAS BEEN POURED INTO THE MOLD, IT IS ALLOWED TO COOL AND SOLIDIFY. THEN THE MOLD IS BROKEN AWAY AND A CASTING EMERGES. IT MAY BE A GOLD RING, A BRONZE STATUE, AN ENGINE BLOCK FOR AN AUTOMOBILE, A PART FOR A JET AIRPLANE OR ONE OF THE MANY IMPLEMENTS OF WAR.

SOME ADDITIONAL DETAILS MAY BE HELPFUL TO FURTHER CLARIFY THE LOST WAX PROCESS.

SHELLING, OR MAKING THE MOLD AROUND THE WAX MODEL, IS SOMETIMES CALLED "INVESTING"..ONE MEANING OF THE WORD "INVEST", IS TO "CLOAK". THE SHELLING IS DONE BY REPEATEDLY COATING (DIPPING) THE WAX MODEL WITH SLURRY AND THEN SPRINKLING THE COATED MODEL WITH SAND. EACH ANOTHER COATING IS APPLIED WHEN THE PREVIOUS COATING HAS COMPLETELY DRIED. THE COATING (OR DIPPINGS) USUALLY PROCEED AS FOLLOWS: FIRST, ONE COAT OF SLURRY ONLY; THEN, TWO COATS OF SLURRY AND FINE SAND, FOLLOWED BY SIX COATS OF SLURRY AND COARSE SAND; AND FINALLY, A SEALER COAT OF SLURRY. THE CERAMIC SHELL MOLD PRODUCED IN THIS MANNER WILL BE ABOUT 1/2 INCH THICK. THE RESULTING SHELL IS STRONG ENOUGH TO WITHSTAND FORCES GENERATED BY THE METAL FLOWING INTO THE MOLD. THE MOLD MUST BE STRONG. IF THE MOLD IS WEAK AND/OR TO THIN IT CAN CRACK OR BREAK OPEN AND ALL IS LOST............THEREFORE THE MAKING OF A GOOD SHELL MOLD IS A MUST.

THE TIME BETWEEN COATS (DIPPINGS) CAN VARY FROM 3 HOUR TO 8 HOURS DEPENDING ON THE CIRCUMSTANCES INVOLVED . THE SHELLING MAY TAKE AS LITTLE AS , ONE DAY OR AS MUCH AS A WEEK TO COMPLETE. THE OBJECTIVE IS TO CREATE A VERY STRONG, DETAILED MOLD, WITH AN ADEQUATE CUP/SPRUE SYSTEM THAT WILL WITHSTAND THE STRESS OF "BURN OUT" AND THE ENTRY OF THE MOLTEN METAL INTO THE MOLD

DURING THE "POUR".

THE "BURN OUT" IS THE REMOVAL OF THE WAX MODEL FROM THE MOLD BY SUBJECTING THE MOLD TO INTENSE HEAT. THE MOLD IS PLACED, CUP DOWN, IN A VERY HOT OVEN (1500 F). THE WAX MELTS AND FLOWS OUT OF THE MOLD. THE MOLD IS NOW DEWAXED AND EMPTY. THE MOLD IS ALSO VERY HOT ABOUT 1500 F AND IS READY TO BE POURED.

USUALLY, BUT NOT ALWAYS, THE POUR TAKE PLACE RIGHT AFTER BURN OUT. ON OCCASION, THE BURNED OUT MOLD IS ALLOWED TO COOL DOWN VERY VERY SLOWLY AND STORED TO BE CAST AT ANOTHER TIME. TO POUR A PREVIOUSLY BURNED OUT MOLD, SIMPLE REHEAT THE MOLD TO ABOUT 1500 F AND POUR THE MOLD.

I HAVE MADE AN ELECTRIC "POT" THAT WILL MELT ABOUT 10 LBS OF BRONZE IN ABOUT AN HOUR. IT IS CALLED .................THE MELTING POT .... (PATENT number 5,539,183 as of July 23rd 1996) .......THE MELTING POT FURNACE ALLOWS ME, OR ANYONE FOR THAT MATTER, TO CAST METAL SAFELY, CONVENIENTLY AND AT A VERY LOW COST. THE LOST WAX PROCESS HAS GIVEN ME A CONNECTION WITH "THE ELDERS" THAT I COULD OBTAIN IN NO OTHER WAY. THE LOST WAX PROCESS GIVES ME A PROFOUND AND

MEANINGFUL EXPERIENCE EACH TIME I CREATE AND CAST MY OWN ART WORK. THIS ARTICLE IS ONE WAY I CAN SHARE THE INFORMATION, IF NOT THE EXPERIENCE WITH OTHERS...............