Art Galleries

This content was published: August 1, 2010. Phone numbers, email addresses, and other information may have changed.

Multiple artists – Our Work: The Process

Rock Creek Helzer Gallery

August 2010

Pit (barrel) firing

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  • Combustible materials and other elements are used in hopes of some chemical transfer to the unglazed clay surface during the pit firing.
  • Materials such as seaweed, copper carbonate, paper, etc. can be applied directly to the clay surface.
  • These pieces have been prepared for loading in the pit (barrel) for firing.
  • Layers of combustibles, copper carbonate, salt, driftwood and pots are alternated. Pots must be stacked carefully. As the firing progresses, combustibles burn and shifting of the ware occurs.
  • Another layer of pots and firing materials.
  • The pit (barrel) is ready for lighting. One last check before the match is tossed.
  • The barrel has air holes strategically placed to allow oxygen to feed the fire.
  • A lazy flame is allowed to heat things up for a couple hours before the pit (barrel) is covered and the ware allowed to soak up the carbon atmosphere and added elements inside. These elements are absorbed and transferred to the surface of the raw porous clay surface.
  • The firing process takes approximately 4-5 hours. The kiln is allowed to cool somewhat before the pieces are removed with gloves and tongs. True results are not apparent until the debris is brushed off the pieces. The surface is further enhanced by applying a liquid polymer that seals the surface and enriches many of the subtle colors achieved during the firing.
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Saggar firing

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  • Saggars are closed environments used to locally affect the unglazed surface of the clay. Combustible materials and other elements are added to the saggar before being sealed and fired.
  • Materials such as seaweed, copper carbonate, paper, leaves, etc. can be applied directly to the clay surface to achieve a chemical transfer during the firing.
  • Other materials are added before and after the clay object is inserted into the saggar. These will affect the surface of the piece through direct and indirect contact. The saggar is then sealed.
  • The sealed saggars are stacked and fired to approximately 1600 degrees Fahrenheit in a gas kiln. The process takes approximately 2 hours. The kiln is allowed to cool naturally, then is unloaded.
  • Different materials will leave different markings on the unglazed clay surface. Opening the saggars is often exciting and sometimes disappointing.
  • The results are not apparent until the debris is brushed off and the pot is scrubbed.
  • The surface is further enhanced by applying a liquid polymer coating that seals the surface and enriches many of the subtle colors achieved during the firing.

Wood-salt firing

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  • The salt introduced to the heated atmosphere inside the kiln vaporizes and adheres to every surface inside the kiln. For this reason "wads" are made of a material that will not be coated and each piece and all shelves and posts are "wadded" to prevent them from sticking to shelves.
  • Starting at the bottom the kiln is loaded, shelf after shelf is added until it is full. Shelves are staggered to allow the wood-salt ash and fumes to better circulate throughout the kiln and better coat the pieces.
  • The lid is lifted into place and the "damper" vent lined up in the proper location.
  • A "damper" is assembled to control the amount of oxygen in the firing chamber during the firing.
  • Fire bricks are stacked to make a short chimney to help create oxygen draw over the vent and damper.
  • The first fuel used, and throughout the firing, is propane. The burner is lit and the heating begins.
  • Through a "stoking hole", wood that has been soaked in salt water and dried is stoked every few minutes after approximately 2000 degrees Fahrenheit is reached.
  • For about 3 hours we take turns stoking every 5-7 minutes.
  • Each piece of wood creates instant flame and smoke out the chimney which lasts for approximately 30 seconds. This is creating a reducing atmosphere.
  • We continue this process until we reach 2350 degrees Fahrenheit. The damper is shut and tall openings sealed to allow for slow cooling.
  • The kiln is allowed to cool slowly before opening 1 to 2 days later.
  • One of the unique characteristics of this type of firing (wood-salt firing) is a natural salt glaze on the raw clay surface. The colors in this photo are from normal glazes, the exteriors have areas of a random, unpredictable pattern of the clay color and the orange-ish salt glaze that occurred by the introduction of the salted wood stoking.

Raku firing

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  • The specially-designed raku kiln is loaded with pieces that are glazed. Pieces for "naked raku" are not glazed – they will be treated after being fired to 1500 degrees Fahrenheit.
  • Lidded containers are prepared with combustible materials such as newspaper, pine needles, leaves, etc.
  • The kiln is fired to 1900 degrees Fahrenheit in approximately 30 minutes. The pots are then removed using gloves and long tongs.
  • Hot glazed pieces are placed in a prepared bucket for reduction.
  • The combustible materials instantly ignite after coming in contact with the hot pot. A lid is placed on the container to smother the flames and create a carbon reduction atmosphere.
  • Applying horse hair is a form of "naked raku". No glaze is used so the applied hair will transfer its carbon markings to the hot clay surface in unusual and unique patterns.
  • Peel away slip is a type of "naked raku" and is scrapped off of the piece, revealing the white clay body and carbon reduction markings that penetrate cracks of the slip.

Cone 6 oxidation

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