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5. Dip sprued wax pattern in a ceramic slurry, drain to
even out coat, then coat with sand. Allow to dry. Repeat
this process until the shell is built to a sufficient
thickness over and around the wax pattern inside.
6. Melt the wax out of the shell. Wherever wax was will now
be a hollow area inside the ceramic shell. Later bronze will
fill that hollow area, causing the bronze to take the same
shape the wax was. CASTING
1. Melt bronze in a crucible to approximately 2000 degrees F
and preheat the shells to approximately 1600 degrees F.
2. When the bronze reaches the necessary temperature, remove the
crucible from the furnace, skim impurities from the top and
monitor temperature until it has cooled to the desired
pouring temperature.
3. Remove preheated shells from the furnace and stabilize
them for pouring.
4. Pour molten bronze into the shells.
5. Once the shells have cooled, break off as much shell as
possible, then sandblast off the remainder. Cut off the sprues, leaving only the casting.
METALWORKING
1. Fit parts of the sculpture together and weld.
2. Use grinders and other tools to retexture wherever
welding was done so that the metal looks like the original
sculpture.
3. Sandblast the sculpture to remove burns from welding and
the shine resulting from grinding and polishing.
4. Check the casting for flaws, repair and re-sandblast to
clean the metal surface one last time.
PATINA
“Patina” is the application of chemicals to the surface of
the bronze to achieve different colors and patterns. Most
chemicals are applied after heating the metal with a torch
so that the chemical will react with or stick on the metal
immediately. Chemicals can be sprayed, misted, brushed or
stippled to create desired effects. Chemicals are often
layered on. |
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