AVANOS CERAMIC FIRING TECHNIQUES WORKSHOPS 2012

SAGAR and RAKU FIRING

SALT KILN

“Salt firing is a vapor-glazing process where salt (sodium chloride) is introduced into kiln firebox at high temperature. The salt vaporizes, and sodium vapor combines with silica in clay surface, forming extremely hard sodium-silicate glaze” [1].

“The process of  Raku firing differs from other firing methods because the pots are removed from the kiln at their maximum temperature. Thermal shock of this rapid cooling is stressful on the pottery. It is achieved by using an open clay body. The porosity of the clay body acts like a shock absorber, preventing the body from immediately fracturing when the pot is removed from the kiln. Raku glazes are often fractured,  which are referred to as Crazing.  These crackle glazes are enhanced by the post firing smoking of Raku pots that embeds carbon into the crackles of the glaze” [2].

RAKU FIRING

NAKED RAKU

“Naked Raku is as the name suggests, naked, meaning that the end result has no glaze on it, just the bare clay surface.” [3]

“A saggar is a container surrounding the ceramic ware as it is being fired in the kiln. The purpose of the saggar is to provide an environment for fuming. Various materials such as garbage, seaweed, straw, sawdust, wood excelsior, magazine pages, copper or brass wire, salt, copper carbonate, iron oxide, cobalt carbonate are placed in the saggar or tied to the pieces. At the firing temperature, these create a "fuming" atmosphere and the chemicals are transferred to the surface of the clay to form random and serendipitous patterns and designs of color. The color range is black, gray, pink, maroon, orange, blue, green and other colors depending on what chemicals are used in the saggar” [4].

SAGGAR FIRING

“Horsehair raku is another technique that requires no glaze.The piece of pottery, which has previously been bisque fired, is loaded into the hot raku kiln. At about 1400 °F it is removed from the kiln with long tongs and set upon a turntable. Quickly, and carefully, strands of horsehair are laid on the surface of the pot.They immediately "frizzle" and smoke. The burning hair leaves its mark permanently on the face of the pot. The smoke also leaves its mark giving the piece a smoke "blush". Once the desired pattern of burned hair is complete the pot is allowed to cool naturally. Afterward the ash residue is washed from the pot and when it is thoroughly dry it is waxed and buffed to a soft sheen “[5].

HORSE HAIR RAKU

“Raku is a pottery technique that has it's origins in 16th century Japan. We are pretty sure that it was developed by Korean potters under Japanese rule but the exact circumstances of it’s development and in what context it was discovered is a mystery. The raku technique, like other pottery techniques such as salt glazing and pit firing, primarily revolves around it's firing process although involvement with raku often goes much deeper into its philosophy, roots, and cultural significance. Traditional raku and western version of raku are similar in many ways though there are some significant differences” [6].

RAKU FIRING

Raku Firing

Saggar Firing

1. http://ceramicartsdaily.org/category/firing-techniques/salt-firing/

2. http://robertcomptonpottery.com/Method%20of%20Raku-Firing-Pottery.htm

3. http://alistairceramics.com/english/aboutnakedraku.html

4. http://www.nelsonmoore.com/art/SaggarFiringWorkshopHandoutwPicsSm.pdf

5. http://annearmstrongpottery.com/process3.html6. http://www.ceramicstoday.com/articles/

branfman_raku.htm

REFERENCES