How to Cast Rings

Cast rings for jewelry or other purposes using the lost wax technique.

Anyone can cast rings at home using the ancient lost wax casting technique and the right equipment. Termed "lost wax" because the carved wax rings inside the mold burn out in a kiln, this casting method is basic enough for a novice to complete with success. Sterling silver is the ideal metal to use for those new to metal casting because of its low price, low melting point and attractive appearance, but bronze or copper will also work.

Things You'll Need

• Jeweler's wax
• X-Acto knife
• Warm water
• Wood dowel
• Petroleum jelly
• Wax pen
• Wax wire
• Lost-wax flask
• Investment plaster
• Water
• Spoon
• Metal tongs
• Kiln
• Centrifugal casting machine
• Crucible
• Metal grains
• Cold water
• Ring vise
• Jewelry saw
• Fine metal jewelry file
• Toothbrush
• Buffing wheel

Instructions

1. Make wax rings out of jeweler's wax. Cut thin strips out of a sheet of wax with an X-Acto knife. Dip each strip in warm water to soften the wax, and then wrap it around a wooden dowel lubricated with petroleum jelly. Cut the strips to fit around the dowel and join the two ends using a heated wax pen. Slide the wax rings off the dowel.

2. Attach sprues, or solid wax wires, to the wax ring models. Cut a piece of wax wire 3 inches long. Heat one end of the wire with a wax pen. Press the melted end of the wax wire onto the side of a wax ring to join. Sprues serve as a base of support when pouring the mold, holding the ring up in a way similar to a flower's stem; once the wax burns out, the molten metal travels through the tunnel left by the sprue into the ring space.

3. Place the rubber flask base on a table. Slip the free end of the sprue into the center hole of the base, and then slide the walls of the flask over the base. Mix fine investment plaster with room temperature water until very smooth. Pour the plaster and water mixture carefully into the flask with the mounted wax ring. Tap the sides of the flask during pouring and for five minutes afterward to release air bubbles. Allow to dry for 12 to 24 hours. The dried investment plaster is the mold for the cast ring.

4. Heat the kiln to 100 degrees Fahrenheit. Place the filled flask inside the kiln and gradually raise the temperature to 1,200 degrees Fahrenheit. Heat the flask at 1,200 degrees Fahrenheit for one hour to further dry the investment plaster mold and burn away all the wax of the ring and sprue. Reduce the temperature to 400 degrees Fahrenheit. Remove the flask from the kiln using metal tongs.

5. Pour the metal when the investment mold is still warm. Turn the flask upside down and remove the rubber base. Place the mold inside the centrifugal casting machine with the base side up. Heat the metal grains in a crucible until they melt into liquid. Pour the molten metal into the investment mold. Turn the casting machine on; turn it off when all the metal disappears.

6. Allow the mold and metal to cool for 45 minutes. Remove them from the casting machine with metal tongs and quench in cold water. Let sit for one hour to allow the investment to dissolve and the ring to cool. Remove the cast metal ring with tongs.

7. Secure the metal ring in a ring vise. Saw off the attached sprue with a fine jewelry saw. File down any irregularities on the ring with a fine metal file. Wash off plaster residue with warm water and a toothbrush. Polish the metal ring on a buffing wheel. Repeat the process to make as many cast rings as desired.

Tips & Warnings

• Use flux to clean the crucible before melting silver or gold to keep the metal free of impurities.

• The wax pen, razor blades, kiln and molten metal used in the ring casting process all carry significant danger of injury; use caution, eye protection and skin coverage when working with sharp or hot objects or processes.

References

• "The Complete Metalsmith, An Illustrated Handbook"; Tim McCreight; 1989
• "Professional Jeweler Magazine"; Article Archives; Cast jewelry: A Primer; Mark B. Mann, May 1999
• Emporia State University: Working with Silver