Lost Wax Burnout in an Electric Kiln
Lost wax casting is the process of carving a shape in wax, making a mold of the wax shape, and then casting that shape into metal from the mold.
The mold is a negative image of the wax. The wax is melted out of the mold through hollow channels called sprues.
Lost wax burnout is the process of preparing a casting mold for the melted metal that will be poured into it. The steps in lost wax burnout:
1) Melt the wax from the mold.
2) Remove wax from the kiln before raising the temperature higher than 300°F/148°C.
3) Harden the mold at high temperature.
4) Maintain the mold at the casting temperature recommended for the type of metal that will be poured into the mold.
Prevent wax or carbon from contacting the kiln’s walls and elements. Carbon build-up inside a kiln ruins the interior. Carbon conducts electricity and causes elements to short circuit. Damage to elements from contact with foreign materials is not covered by warranty.
1) Place a metal tray inside the kiln on three ½” posts. Place the mold on a wire mesh screen on top of the tray. The mold’s sprue holes should be down. The tray will catch melting wax as it drips from the sprue holes.
2) Keep the kiln’s vent hole(s), if any, open during wax elimination. If the kiln has no vent hole, leave the door open ½”. This allows fumes to escape from the kiln. Heat the kiln to 300°F/148°C and hold it at that temperature for at least one hour.
Do NOT heat the wax above 300°F/148°C. Hold at 300°F/148°C for at least one hour. During this hour, the wax will melt from the mold and drip into the tray. If the kiln gets hotter than 300°F/148°C, the wax may smoke and deposit carbon inside your kiln, causing expensive damage.
3) After one hour at 300°F/148°C, open the kiln. Remove the mold and wax tray. Pour the wax from the tray and leave the tray out of the kiln until your next wax elimination. (Do not leave the tray in the kiln!)
4) Heat the mold to the temperature recommended by your jewelers’ supply house where you purchased the mold material. This is usually around 1350°F/732°C.
5) Lower the temperature to the casting temperature of the metal. Hold at that temperature until you are ready to begin casting. Remove the mold with tongs. Wear protective gloves and safety glasses.
Saving a Carbon-Damaged Kiln
If you follow the above directions, your kiln should be safe from wax damage. In some cases, a small amount of carbon may form on the walls over a period of time. This is due to the burning of wax residue that was left in the mold. For this reason we recommend that you periodically fire the kiln to 1500°F/815°C as follows:
1) Open the vent cover(s) or leave the door ajar ½”.
2) Fire the kiln empty to 1500°F/815°C at a rate of 300°F/166°C with a one hour hold (01.00).
Wishing you a prosperous 2004,
Arnold Howard Paragon Industries, L.P. firstname.lastname@example.org