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How to do a Black-Firing

Black-firing is an ancient, simple, low temperature firing technique. The method described here involves heating a primitive gas-brick kiln to about 1000oC and then adding sugar, which then volatilizes and impregnates the clay with carbon, giving it a matt black surface.

Difficulty Level: average      Time Required: 6 hours

Here's How:
  1. Stack the black-fire kiln carefully so that flames will wrap around the work and exit the flue. Work placed near the flue will receive more heat.
  2. If using glazes, place glazed test rings near the spy hole to check the glaze maturation during the firing.
  3. Place a cone 013 (855o C/1565o F) in the kiln and insert a pyrometer if available.
  4. Begin the firing slowly for the first hour and then turn up the gas pressure every hour for up to 5-6 hours.
  5. Shut off the gas and seal the flue and any cracks.
  6. Push in up to 16 pounds (5-8 kg) of sugar into the burner port and then seal the port with bricks and fire clay. (A good gas mask and heavy duty leather gloves should be worn at this stage.)
  7. Make sure all cracks, where smoke is billowing out, are sealed with fire clay as well as possible.
  8. Allow the kiln to cool overnight and open the next day.
  9. Remove excess scum with a wire brush under a running tap.
  1. Use old kiln shelves.
  2. Keep a long, thin metal rod handy to pull out test rings.
  3. Be sure to wear a gas mask, not just a dust mask, when adding the sugar -- the fumes are toxic!

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