Lost-wax casting starts with a wax shape and a mould of the shape. When the mould is heated, the wax melts out, usually over a burnout grate and into a tray. The shape is then cast.

Lost-wax burnout starts with making a wax shape and then making a mould of the shape. When the mould is heated in a kiln, the wax melts out through channels, usually over a burnout grate and into a tray. The shape is then cast in glass or metal from the mould.

It's important to prevent wax or carbon sticking to the elements, so burnout kilns have a top vent to release the fumes. Carbon build-up inside a kiln conducts electricity and can cause the elements to short circuit.

I've written some general instructions here but, as always, making anything successfully needs critical research and frequent tests, especially as things that work for your friends and teachers might not work in the same way for you. It's also very important to learn how to creatively use unexpected effects.

The most popular kilns for lost wax processes are the Paragon W series: the W13, W14, and W18. Learn about these by using the w:lost-wax-burnout link below the menu bar near the top of the page. Wax burnout trays, glare-resistant glasses, and heat-resistant gloves are in the on-line shop.

How to do lost wax burnout ans casting.

1 : Place a metal tray inside the kiln on a few 12mm posts. Place the mould on a grate on top of the tray. The mould’s sprue holes should face down. The tray will catch melting wax as it drips from the sprue holes.

2 : Keep the kiln’s vent hole open during wax elimination. If the kiln has no vent hole, leave the door open 12mm. This allows fumes to escape from the kiln. Heat the kiln to 148°C and hold it at that temperature for at least one hour. Do NOT heat the wax above 148°C.

3 : During this hour, the wax will melt from the mould and drip into the tray. If the kiln gets hotter than 148°C, the wax may smoke and deposit carbon inside your kiln, causing expensive damage.

4 : After one hour at 148°C, open the kiln. Remove the mould and wax tray. Pour the wax from the tray and leave the tray out of the kiln until your next wax elimination. Don't leave the tray in the kiln.

5 : Harden the mould to the temperature recommended by your mould material manufacturer.

6 : Finally, adjust the temperature to the casting temperature of the glass or metal. Hold at that temperature until you are ready to begin casting. Remove the mould with tongs. Wear protective gloves and safety glasses.

Over time, a small amount of carbon can form on the firing chamber walls as any wax residue left in the mould burns off. So I recommend that you periodically open the vent or leave the door open 12mm, and fire the kiln empty to 815°C at a rate of 166°C with a one hour hold.

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