METAL CASTING

METAL CASTING

I am sure some of you have wondered how exactly we get to make so many of the same pieces and have them look exactly like each other, and the answer is molds!

I made the first Third Eye ring for personal use, however I shortly realized I needed to make a mold of it so I could share it with others who showed interest.

As per our first chapter "design", when I design a piece, I make what is called a “Master”, this can be hand-carved in wax or 3D printed and in both cases molded so it can be replicated. Here you can see some of the SunRa's masters.

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 fascinating world of lost wax casting.

The molds we use to make our pieces are made of silicon, which is great for the purpose as it is elastic and renders very high detail. Here you can see one of our SunRa ring molds courtesy of our lovely casting shop Taba.

The first step to produce replicas out of a jewelry mold is to fill them 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 the wax injection of one of our Harmony charms.

Each wax injection has a “sprue” attached, which is basically a stick of wax. These are used to connect the wax models onto a “tree” of wax in which each model is connected to the main rod like a branch of a 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 it.

After the plaster (also called investment) is hardened, the flask is heated to melt the waxes away and leave the empty spaces instead. (image courtesy of ganoksin.com)

The last step of the casting process consists of shooting very hot molten metal into the mouth of the flask (what used to be the base of the tree trunk) to fill the jewelry-shaped empty spaces with the desired metal. (image courtesy of Tabacast.com)

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, which is normally done by power washing. (Image courtesy of jewelry-tutorials.com)

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 subsequent civilizations to make jewelry, tools, vessels and sculpture. I tried my best to explain the process in a simple and approachable way but if something isn't clear or you are still curious to learn more, wikipedia has a super interesting entry on it!

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