How metal clay firing with a butane torch is an alternative to kiln firing.
Metal clay firing with a butane torch works very well with low temperature metal clays.
There is a varied selection of butane torches available, many hardware stores carry these torches along with fuel canisters.
Precious metal clay pieces should not weigh more than 25 grams for this type of firing.
When using butane torches always ensure that your work area is clear of all flammable material. Use a small fire brick or ceramic fiber tile as your work surface.
If your metal clay piece contains a gemstone be sure that it can withstand the heat. To prevent the stone popping out place it face down on your work surface.
If your piece contains a stone of some sort never quench the hot metal in cold water as the temperature change may cause the stone to shatter or crack.
Have a pair of tweezers handy or heat proof gloves to handle the hot metal if necessary.
Always wear safety glasses for this firing operation.
A timer that you can operate with one hand is highly recommended.
Before clay is fired it must be bone dry, any moisture in the clay may cause it to expand and burst.
Firing Time
As a guide to the firing time the following may be of assistance:
3.5 to 4 minutes minimum for a 20-25g piece.
3 minutes for a 15-20g piece.
2.5 minites for a 0-15g piece.
2 minutes for 5-10g piece.
Always keep the torch moving around the clay piece during firing.
Color Changes
You should turn the lights down as it will be easier to see the color changes during the metal clay firing.
When you first begin firing you will see some smoke as the binders are burnt away, the clay will begin to turn white and shrink, a glow will appear.
The glow should gradually turn to warm reddish orange.
An intense orange glow, an intense red, or if the surface begins to shine means the piece is over heated. Remove the torch immediately.
A shiny surface means that the silver is on the verge of melting completely.
You should aim to keep the silver at the red orange stage by moving your torch constantly and adjusting the distance between the flame and clay.
Commence timing your firing with your timer when you reach the red orange stage.
Providing that the silver does not over heat it won't hurt to go past the suggested timing. Under firing the clay will result in a brittle piece of silver.
The following video will take you through the butane torch firing stages.
