Metal Casting
I am sure some of you have wondered how exactly we get to make many of the same pieces and make them all look the same, the answer is molds! I made the first Third Eye ring for personal use, however I shortly realized I might need to make a mold so I could share the design with others who showed interest. That was circa 2012 and it was the first time I knocked at Taba´s doors. Taba is an amazing full service jewelry shop located in Manhattan´s diamond district. They are the ones who do our metal casting, a process which I will try to explain ahead.
As per our first chapter "design", when we design a piece, we make what is called a “Master” This can be hand carved in wax or 3D printed and then molded so it can be replicated. Here you can see some of the SunRa's masters.
The next step in replicating our master is to make a mold of it. The definition of mold is as follows: a hollow container used to give shape to molten or hot liquid material when it cools and hardens.
Molds can be made in many materials and casted in many different ways, but in this particular case we will be looking at the complex world of lost wax casting.
We use jewelry molds made of silicon, which are great for the purpose as they are elastic and render very high detail.
In order to produce replicas out of a jewelry mold, the molds get filled with hot wax, which fills the negative space creating a copy of the Master. Once the wax cools off it is released carefully from the mold.
Here you can see a mold of our SunRa ring and a wax casting of our harmony charm.
Each wax injection has a “sprue” attached, which is basically a stick of wax. These are used to connect the wax models on a “tree” of wax, which is a thick straight cylinder wax rod. Each model is connected to the stick like a branch of the tree.
Once all the wax models are attached to the tree, it is placed into a metal cylinder, known as a flask, so that a plaster substance can be poured over. After the plaster (also called investment) is hardened, the flask is heated to melt the wax models away and leave instead the empty spaces.
The last step of the process consists of shooting very hot molten metal into the mouth of the flask to fill the jewelry-shaped empty spaces.
Full disclosure: these are two images I stole from the interwebs to illustrate the process.
After molten metal (silver, gold, platinum…) has reached every crevice of the flask and filled in the details of the jewelry pieces, it’s time to remove the plaster and clean the pieces, which is normally done by power washing.
Each piece is then snipped from the tree, and their sprues removed. From here on they can be polished to various finishes and turned into little shiny bits.
As I previously mentioned, this process is called “Lost wax casting” and it is a 5000 year old technique first used by the egyptians and then utilized by many posterior civilizations to make jewelry, tools, vessels and sculpture.
If you still have doubts or a curious about learning more about the process wikipedia has a lovely entry on it.