Waxes: Creating the wax:
Waxes of new pieces are made by carving and "building up"wax to create the model of a new design. Some waxes are made by just carving the model out of a block of wax. Other waxes are built up. In our shop most of our waxes are built up and carved. We use wire tools that are heated over a Bunsen burner. The wire is touched to a block of wax and a small droplet is picked up by the tool. It is then "painted" onto a form or base to build the model. Wax hardens quickly as the tool cools, so layer upon layer can be built up to create a 3D model.
Refining the wax:
I then carve and file the wax to perfect it and to refine details that were built up. Waxes rarely look as good as a finished piece, but sometimes they can come close. Waxes allow our customers to let us know how they like our designs and give us their feedback as the design progresses. They are fairly easy to modify so we can make changes if our customers ask us to modify them.
Rings:
Rings are made by applying the liquid wax to a mandrel. Most mandrels are tapered long, round, metal "sticks" that have ring sizes engraved into them. I use a version that is just one ring size and is only about 2 inches long. It's easier to handle than a long mandrel and it isn't tapered. I apply layer upon layer of wax until I've made a wax band that goes around the mandrel. I then build up the wax until it is a perfect model of the ring.
Drawing with wax:
Liquid wax, can be drawn into the air slowly to extend a feature as it cools. The branches and leaves on our trees as well as the hairs on a unicorn's mane are done like this. One of my favorite examples is below it a setting for an old cameo. I used the techniques here to create it, nearby is the same piece finished. This is a very ancient process.
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Casting: Investing:
Once finished, the model will be placed into a steel cylinder, ( flask), that will be filled with plaster (investment). A thick wax wire called a sprue, is attached to the model. The other end of the sprue is fixed to a cone shaped form in the center of a rubber cap or base. The cone in the base’s center will form a funnel like opening in the plaster at the flask’s bottom once the plaster has hardened and the base twisted off. The thick sprue, supports the model and suspends it near the flask’s center, like a little tree on top of a mound.
Investing:
Next the flask is filled with plaster ( invested ), completely covering the wax model. A paper collar around the top of the flask keeps the plaster from overflowing. The flask is then placed into a vacuum chamber and the air is then vacuumed out. The vacuum causes small bubbles attached to the wax model to grow and erupt out of the plaster. I’m sure you’ve noticed tiny bubbles clinging to a straw in a drink. If the plaster hardens without removing those bubbles, they fill with metal. This results in the casting being covered solid little balls of metal that all have to be removed, wasting time and metal. The flask is vibrated while it is under vacuum which helps remove them. Any bubbles left on the wax after vacuuming are squeezed to nonexistence by the returning air pressure when the bell jar is removed and the plaster is left to set up.
Burn out
Once the plaster has hardened, the flask is placed into an electric oven and heated to about 1300 degrees F. Several hours later the is completely burned out of the plaster. Now there is just a void in the plaster where the wax model once was. The funnel shaped opening left in the bottom of the flask when the base was removed is how the metal will enter. We now reduce the oven’s temperature to one that is best suited to the metal being cast.
Casting
The flask comes out of the oven glowing bright red, I place it into a centrifuge arm’s cradle. The crucible’s open end is gently pushed into the funnel shaped opening in the flask. The crucible and flask ride on the end of the centrifuge arm with the flask at its end. When the centrifuge’s arm spins the melted metal is thrust from the crucible into the flask. We use a torch to melt the metal in the crucible. The metal is melted and held at heat long enough to make sure that it is completely melted and uniform. The metal is “cast” into the flask by releasing a pin allowing the spring driven arm to spin. Molten metal passes out of the crucible through the opening in the plaster to fill the empty model. The flask cools as the arm spins, then I plunge it into water where the plaster explodes from the casting and flask. I’ve made a short video of this process on our Face Book page. Click here to view it https://www.facebook.com/111540785537658/videos/704398492918548/
Custom Order Preview
We often send images of wax models to our customers before we cast and finish their pieces. I Frequently tell customers that if they like the model, they will love their piece when it is finished. Models aren’t very pretty. Seeing the model gives our customers a chance to let us know how they like our design. This helps us make sure that they will love their new treasure. We have some images for you here so that you can see waxes and the resulting pieces created from them. You can also see images of models on our blog where we often post images of models of pieces that are just being made. Â https://postgatejewelers.com/abstract-watermelon-tourmaline-peridot-dangle-earrings/
