After sketching the preliminary design, the artist then begins to work on the actual sculpture. Various materials can be used for this purpose.
Once the original sculpture has been finished, a synthetic mold is made. Next melted wax is injected into the mold. Once the wax has cooled and hardened it is retouched to ensure the all of the original sculpture's details are not lost.
An investment mold is then built around the wax model. The mold with the wax model is then placed in a furance where the wax is “lost”. Next, molten silver is casted into the mold and afterwards the cast silver cross is chased (detailed) and polished.
How do ideas become
By Roland Serna Architect & Sculptor
Visualizing and creating the The Silver Crosses’ sculptures. The very first step is to conceive the idea for the project at hand. I find my inspiration from having traveled and seen classical works of art. There are also many excellent publications in which one can revel in viewing photos of classical masterpieces. I believe that it’s necessary to learn from what has been done in the past in order to be able to educate oneself and then produce one’s interpretations.
After inspiring myself in this manner, I envision a design for a project. And now the fun part begins. I proceed to draw sketches and rough 3d models. I’ll draw as many sketches and make as many models as are needed to help me visualize the project. In this the “rough” stage of sculpting, I’ll make changes where I see that they are necessary. In the last phase, I’ll detail the art piece and inspect it to make sure that it has reached it’s final point of design. That is to say that the piece can no longer be improved and that I’m satisfied with the final results.
The actual execution of the sculpture is reduced to a craft. For my sculptures I use a two materials; the first of the two is a malleable modeling putty and the second is a harder material known as a “jeweler’s carving wax”. As a backing to these two materials I will use either sheet metal or sheet plastic. The putty is modeled with tools that have very small points in a diversity of shapes. With these tools I’m able to get very precise and detailed high reliefs. The carving wax is applied and carved using a jeweler’s “hot wax set” of pens and minute carving tools. However, a sculptor should have no limits as to what materials may be used. It’s always a good practice to improvise with new tools, materials and techniques and to be constantly experimenting.
For those persons that are interested in learning more about this type of sculpture, please feel free to contact me. I can also provide the names of the materials and tools that I use and the sources where they may be purchased.
“Lost Wax” Casting Process
Step 1 Making a mold from the original art work. This is a flexible "Room Temperature Vulcanizing" mold or RTV that is a synthetic rubber like material. It features the ability to pickup all of the details of the original sculpture.
Step 2 Wax injection into the RTV mold. Casting wax is sold in the form of flakes. This casting wax is a synthetic wax that is melted and once it is in liquid form it is injected into the RTV mold and allowed to cool and harden. Once the wax has hardened it is de-molded and it is now called a wax "model".
Step 3 Wax model detailing. Once pulled out of the mold the wax model is almost always slightly
flawed. It therefore needs to be detailed or "chased". This is to say that any missing details are restored and that the wax model is then polished by hand. Once the "model" has had it's details restored it is ready to for the next step.
Step 4 Spruing the model. Sprues are wax rods also known as "gates". These sprues are attached to
the model with a hot wax pen. The sprues will be the conduits from which the molten silver will enter the ceramic mold.
Step 5 The ceramic mold. The wax model and sprues will then be dipped into an investment mold (ceramic mold). The ceramic mold's material is similar to that used by dentists when they pull molds off teeth. The ceramic mold has the ability to record the smallest detail on the sculpture's surface.
Step 6 Burn out. The dry ceramic mold with the wax model and sprues inside is placed upside down in a kiln. the kiln is then heated to a very high temperature and then both the wax model and sprues melt out of the ceramic mold. Hence the name of "lost wax". The ceramic mold is now hollow with the negative imprint of the model and sprues inside. At this point the ceramic mold is allowed to cool off for the next step.
Step 7 Casting. The ceramic mold is now placed in to a spin casting machine. The spin casting machine resembles a large metal "drum". Inside the "drum" is an "arm" with a axis in the center halfway along it's length. At one end of the arm the mold is placed. At the other end is a receptacle with molten metal. The axis has a propelling machine that when it is activated will cause the "arm" to spin with a very strong centrifugal force that will propel the molten silver into the ceramic mold. The whole mechanism is placed inside a metal "drum" for the protection of the operator.
Step 8 Break 0ut. The ceramic shell containing the hot metal is then dunked into a cold water receptacle. With the cold water acting on the mold's ext rior and the hot metal inside, the shell disintegrates exposing the rough metal casting.
Step 9 Sandblasting. The rough casting is then sandblasted to eliminate particles of the shell mold in the silver castings crevices and to clean the casting's surface.
Step 10 Chasing. The rough casting is then detailed with a jeweler's "flexshaft" using various grinders with the object of crisply detailing the details of the silver cross.
Step 11 Polishing. For polishing silver you use a "flex shaft". This tool uses polishing wheels of di ferent grits. The polishing wheels can be placed or removed as needed on the flex shaft To polish silver you begin with the coarsest polishing wheel grit. Then you gradually continue polishing with intermediate grits and finally end with the finest grit which is the one that will give the silver it’s highest degree of luster. You now have a dazzling finished silver cross pendant.