My mold maker Reije Andersson working in his studio
The Lost Wax Bronze Casting Process
To familiarize the bronze art collector with the "lost wax bronze" process, listed below is a step-by-step description of the procedure. It should be realized that this total casting process takes several weeks from start to finish. Thus, realizing the time needed to create a single piece of bronze, the collector gains a greater appreciation for the value of his bronze, whether it is one of a kind or a recast of a noted collectible artist.
1. Original Sculpture
The first step begins with the artist creating an original sculpture. This is usually created from wax or clay, though other materials can be used as well.
2. Rubber Mold
mold is made from the artist’s original. This mold captures every detail put
into the artist’s original work, and is one of the most critical phases in the
bronze process. This mold is used to create duplicates of the original design.
3. The Wax Casting Process
The molds are then used to form wax figures; molten wax is poured into the rubber mold, producing a perfect copy of the original sculpture.
4. Wax Chasing
The wax casting is removed from the mold, and a trained artisan hand- finishes the wax pattern to original perfection. Each wax casting is treated as if it were an original work of art.
Wax rods (gates) are attached to the wax pattern to allow the even flow of molten metal and to alleviate the trapping of air and gas. A sprue cup is placed onto the wax to receive the molten bronze.
The wax is then coated with an “investment,” a liquid re-factory ceramic. Several layers are applied creating a stable mold that is allowed to cure for several days.
The piece, now coated in ceramic shell, is fired in a kiln. This bakes the shell and eliminates the wax, leaving a cavity in its place. (Thus, the term, “LOST WAX”)
The ceramic shell is removed from the kiln and molten bronze is immediately poured at a temperature of 2100° Fahrenheit. (Bronze is an alloy of 95% copper, .02% lead, .02% tin, .06% zinc, and 4% silicon.)
After cooling for several hours, the ceramic shell is carefully broken away, revealing the bronze sculpture within.
10. Sand Blasting
Fine sand particles are blasted under air pressure to remove the last traces of ceramic shell that adheres to the bronze.
An artisan cuts away the sprues and gates. After this, the pieces of the sculpture are welded together by skilled craftsman.
By grinding, chasing, sanding and polishing, all areas are blended back to make the bronze look exactly like the artist’s original sculpture.
bronze is now treated with chemicals and heat to give it the chosen color
according to the artist’s specifications. The patina is sealed under a wax
coating and becomes part of the sculpture.
S . C
|Dari Walker (C) 1996-2004||Phone: (800) 285-2860|