I was recently asked to convert a selection of a customers old and inherited gold into a new piece for her to wear and enjoy. We planned a sculptural ring that would be a bold, statement piece. I began by carving the ring in wax, translating my drawings into 3D to get a feel for the ring that I wanted to make.
As we particularly wanted to recycle the clients own gold into the new ring I chose to cast the ring myself, so that I could guarantee that her gold was used for the final ring. Melting the gold is a fairly simple process, however the casting itself was a learning curve for me.
I initially chose the sand casting method as it’s noted for the accuracy of the impressions that it gives. I used a Delft sand casting kit where an oily, red, almost clay-like sand is used to form a single use mold for the piece that you wish to cast. The process of loading the mold is simple, if a little time consuming, and allows you a lot of control over how to pour the metal into the form.
After a few attempts it became clear that the process wasn’t quite as simple as I was hoping. Melting and pouring the gold was relatively easy but the high temperature required to keep the gold molten made it difficult to ensure that the metal flowed properly around the mold. Several castings came out only partially filled:
The cold sand sucked heat out of the metal and prevented it from filling the mold. I tried variations on the layout of air holes, the entry position of the metal and even the angle at which I poured the metal. The most complete casting that I managed to yield was pitted and too imperfect to work with.
I read through a lot of troubleshooting information online but couldn’t find a concrete answer to the problem.
In the end I decided to go simple and try cuttlefish casting the ring instead. It’s a method that I haven’t used since college and wasn’t my first choice because the cuttlefish bones can transfer their distinctive markings onto the final casting. However, the sand casting wasn’t working out so I figured that it was worth a shot.
I pushed the silver master pattern into the cuttlefish which yielded a surprisingly smooth mold, though it did require quite a bit of force to make a complete impression. I carved extra air escape points into the cuttlefish and a funnel, to pour the liquid gold into. This method worked first time, I think because it was easier to keep the temperature of the metal high once it entered the mould.
A cuttlefish mould can only be used once, pouring molten metal into it destroys areas that it touches, burning away the cuttlebone.
Cleaning up my final casting was easy and I was delighted with how neatly the mould had filled. I cut away the large sprue, which indicates the point at which the gold was poured into the cuttlefish and refined the shape of the ring to bring out that crisp, knife edge.
Once sanded and polished the final casting is a beautiful copy of the silver original that I made. The ring carries a 9ct hallmark but mixing up the clients old 9ct & 18ct gold actually resulted in a 12ct ring. The unpredictability of alloying family gold in the workshop is always fun and this ring has a wonderfully warm, red overtone: