The Art of Lost Wax Casting

by Rebecca Tassell

Just behind the Basillica of Santa Croce sits a quaint artisan shop filled with true Florentine jewelry designs. Inside you will find the works of DFG Firenze aka “The Bottega.” The three owners, Roberto Dorovandi, Riccardo Filippini and Stefano Gabrieli, opened the shop in 1995 and have since been perfecting the art of the Lost Wax Process of jewelry casting, as well as creating their own designs.

They opened their doors to my wax carving classmates and me. As a newcomer to jewelry design, I found the whole process very intriguing. An immaculately organized shop with one buzzing machine after another, The Bottega was the perfect setting to learn the trade.

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The purpose of this process is to quickly reproduce a metal model of the original wax design. Easier said than done. Once there is a metal model, the vulcanizer can be used to create a rubber mold of your piece. The rubber mold is taken to the wax injector, which does exactly what it’s name implies. By injecting wax into the mold you can quickly reproduce multiple wax models and compile them onto a “sprue”.  Soon I’ll be able to use these machines in class to design a cuff made of tiny leaves.

After Stefano showed us the vulcanizer and wax injector we moved onto the vacuum casting and centrifugal machine, which mixes “investment”, a fancy term for a paste made of plaster and water. The investment is poured over the sprue, which has been placed inside a water-tight metal flask. Once poured over, a vacuum suction removes all air bubbles from the plaster so that it hardens correctly. 

The investment, with the wax model inside, is then moved to the kiln and gradually heated over a span of twelve hours until it reaches 700º Celsius (1,292º F for Americans)! Stefano leaves the molds in overnight so they’re ready when he gets to work the next morning. As the investment is heated and dried, the wax melts completely, leaving an empty space in the shape of the model.

Finally, the investment mold is placed in the metal injector. The metal liquefies and fills the empty space in the investment. Stefano prefers to leave the flask to cool for 5 minutes before picking it up and running it under water. The shock to the very hot metal when the cold water hits the flask causes the investment to break. Voila! The metal models are created.

It was exciting to see how the shop works and to get a thorough understanding of the lost wax process. An art that takes much practice and patience, but a necessity for design replication. I’m glad we had the opportunity to experience the process first-hand with the guidance of such dedicated professionals who love their work!

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Becca Tassell is in the Jewelry Design certificate program at Lorenzo de’ Medici. She graduated from Brown University in 2012 and was working in New York City for three years in fashion E-Commerce. After completing LdM’s jewelry design program Becca plans to work as a jewelry designer (preferably in Europe) before starting her own company.