Lost wax casting is fast becoming an interesting and satisfying outlet for my imagination. I think it’s indispensable in combination with 3D extruded models and I can hardly wait to test run my first attempts at combining the two disciplines.
For those not familiar with casting, I’ll explain in as layman like fashion as possible. Before we began, our instructor showed us a design from another class that took twenty hours to develop. It resembled a flowering bud with leaves designed as latticework and about 3/4 of an inch in diameter. The artist sculpted each wax leaf by hand, arrayed them circularly at an angle and then arrayed and layered successively smaller versions above. I remarked to the instructor that 3D modeling software could accomplish the same task in about 5 minutes. Extruding the design with a good 3D printer would take about 15 minutes.
For the first class, we were given an overview of the steps involved, and the equipment that would be used to complete the design of our choosing. My first wax design is a medallion, which admittedly could have used more detail, but I’ll be extruding my waxes by 3D software design and extrusion by 3D printer where I’ll have greater control of an intricate pattern, so at this time I’m more interested in the development of casting technique than detail. Still, it’s a satisfying effort to understand how to cut, design and manipulate both the wax and the tools needed to develop a good design. I can see where many hours could be spent on just this first step, depending on the detail and intricacy of your design.
The second class gave us the method to attach our wax model to a synthetic base which is attached to a circular metal casing or “cup”. We attached our wax to the base with a “sprue”, a branch-like stem of wax that provide a path for the molten casting material to flow and for air to escape. The base is then attached to the cup and a slurry of silica “plaster” is poured into the cup and allowed to harden. The base is removed, exposing the end of the sprue. This casing is then placed in a kiln for the burnout process, which melts out the wax and leaves the void of the design in the plaster cast.
Our next class will show us how to measure out the casting material by weight and melt the metal in a crucible, then pour into our casting. See you then.
Quote of the week:
“If anybody here has trouble with the concept of design humility, reflect on this: It took us 5,000 years to put wheels on our luggage”. — William McDonough