How to Cast Platinum & Gold By Jewelry Designs

How to Cast Jewelry

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Alloying Gold

The first step in casting is preparation of metal. At Jewelry Designs, we alloy gold to the karat and color that is needed for each project. We cast jewelry daily in 14kt, 18kt, 24kt, and platinum. When preparing karat, gold color can be achieved by varying the alloys that are mixed with the pure gold. Adding nickel will yield white gold, copper will yield rose, and silver will yield green.
By alloying and casting our jewelry, we can be certain of the quality of the precious metals.

Investing Wax Ring Models

After wax models are carved, they are attached to a wax tree and mounted on a base. In this photo, the base and models are incased in a canister which will be filled with a temperature-resistant, plaster-like material called investment.
Various blends of investment are used with different properties for different metals and situations. After the investment is poured into the canister, it is placed in a vacuum chamber to remove any trapped air before it is allowed to cure.

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Jewelers Wax Burnout Procedure

Once the invested canisters containing the wax models are fully cured, they are placed in specialized ovens where the wax is incinerated at temperatures as high as 1600° F for 12-16 hours. A properly burned out flask, such as the one in this photo, has no remaining residue of the wax. What remains is a hollow impression of the tree and sculptures that were burned from it. Through the use of centrifuges, we will fill the hollow chamber with molten precious metal.

Platinum Casting After Burn Out

This is the final platinum casting after molten platinum was spun into the empty flask. You can see the same images in platinum as are pictured in wax in the previous illustrations.
After the flask and metal cooled, the plaster was chipped away to reveal the platinum tree. The pieces can now be cut from the tree and finished, so that the necessary torch and setting work can be done.

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Gold Casting

In our shop we use centrifuges to cast our gold jewelry. After a flask is completely burned free of wax and residue, the flask is removed from the oven and placed in a "cradle" on a centrifuge.

Melting the Gold

In this centrifuge, you can see molten gold in a crucible with the cradled flask backed up against it. The opening in the flask, where the wax was burned from, is lined up with a spout on the crucible. When the metal is at just the right temperature, the centrifuge will be released, and gold will flow freely through the spout into the empty cavity in the flask.

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Centrifugal Casting Jewelry

Here, you can see the red-hot centrifugal arm in motion.
The flask fills with molten gold immediately, and the centrifuge will slowly spin to a stop as it cools. When the flask is cool, the plaster is chipped away from the gold casting and tree.

Wax to Gold Comparison

Here is a before and after example of a simple wax tree and the finished gold tree. On the left, you can see a single wax carving that is affixed to a wax rod and base. A metal canister was placed over it. The flask was filled with investment and burned out. The empty cavity was filled with gold, and the result is the gold casting in this photo.

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Platinum Wax Model

These wax wings were hand-carved from modeling wax. The wings were then attached to a wax tree and mounted in a canister which was filled with investment. The specially blended investment slurry was then cured into a ceramic-like mold that can withstand the extreme 3224° F temperatures of molten platinum.
The wax butterfly wings were burned from the flask for 12 hours in a high temperature oven yielding a mold with a hollow impression of the sculpted wings.

How Platinum is Cast

The burned-out flask of the butterfly wings has been placed into the cradle of a high frequency casting centrifuge. In this photo, the technician is melting platinum with high frequency radio waves in preparation for the cast. When the platinum reaches its optimal molten point, the centrifuge will be released and platinum will flow into the vacant cavity that was once occupied by the incinerated wax wings.

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Finished Platinum Castings

These are the two wings in the above illustrations. After casting, the ceramic-like material was removed by boiling them in acid for several hours. The final butterfly weighed over 3 oz. in platinum; however, over 9 oz. of platinum was needed to properly fill the molds. The cast wings must now be cut from the tree and carefully finished.

Jeweled Butterfly from Casting

The final platinum butterfly is nearly three inches across and set with 670 precious stones and diamonds totaling 21.58ct.
The body is articulated with black enameling and the undersides of the wings are laced with 18kt yellow gold, hand-pierced latticework. This piece was featured on numerous talk shows and in newspapers throughout America. The complete production of this butterfly can be seen in the "Design" section of this site under "Making a Butterfly".

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Jewelry Shop Directions

Jewelry Designs is the area’s leader in retail and manufacturing of fine diamond jewelry.
Jewelry Designs is located in Danbury, Connecticut in western Fairfield county bordering Westchester and Putnam counties on the New York state line.

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