Raku Pottery Identification

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Raku

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Of all the firing techniques, Raku is probably the most exciting and spectacular, but as a medium, Raku is more decorative than utilitarian.  Raku is derived from the Japanese expression meaning enjoyment or happiness and is the name given to a variety of pottery techniques such as those pictured below.

Raku glazed pots are given a normal bisque firing to about 1850º Fahrenheit before being glazed and placed into the raku kiln. After reaching temperature of about 1650º -- in about 45-60 minutes -- the glazed has melted and the glowing, red hot pot is ready to be removed from the kiln with tongs.  The pot is quickly transferred to a ‘reduction chamber’ (usually a popcorn can or small air tight metal container) with some sort of combustible material such as paper.  Here the glaze is reduced (deprived of oxygen) and the pot undergoes intense thermal shock because of the violent and rapid change in heat.  The picture on the left shows how a copper glazes has produced a flash rainbow of colors.
A Horse Hair pot is given a normal bisque firing to about 1850º Fahrenheit.  The pot is then fired in a raku kiln with no glaze or surface treatments.  When the pot has reached about 1500º the pot is removed from the kiln and horse hair or feathers or other combustible materials are laid against the pot.  This produces the black lines you see on the finished pot.  In some instances, the piece is then sprayed with an iron solution (ferric chloride) to give it a warm, toasty color.
Saggar fired pots are fired in a clay container (ex: clay flower pot) that can withstand high temperatures.  Pots are placed in a saggar container and surrounded with a variety of materials, such as sawdust, charcoal, salt and copper oxides. The saggar is then closed and placed in a kiln and fired to about 1650º F.  During the firing, materials inside the saggar will volatilize (evaporate or cause to evaporate) and flash colors onto the pots and produce areas of intense carbonization.  After the pots are cooled, they are removed from the saggar and coated with a coat of wax to protect the color from the elements.
Crackle pots are given normal bisque firings. The bisque pot is then painted with a crackle glaze and placed into the raku kiln.  When the glaze has melted at about 1850º F the kiln is turned off and the pot is allowed to cool slightly before it is placed into a reduction chamber (popcorn can or an air tight container) that has been lined with paper.  It will cool completely before it is removed from the can.  The carbon from the burnt paper penetrates the unglazed areas and into the cracks in the glaze.
7-Layer pots are given a normal bisque firing.  The bisque is sprayed with a matte glaze to cover up the bisque color.  When the matte glaze dries, a glossy crackle glaze is pored over leaving some of the matte glaze visible.  When that glazes dries, oxides are sprayed on the pot to give it different colors.  After all glazes has dried, the piece is fired in a raku kiln to about 1850º.  The kiln is turned off and allowed to cool to about 1650º.  The piece is removed from the kiln and placed into a reduction chamber (popcorn can or small air tight container) that is lined with a small amount of paper.  The lid is cracked open on the container for about 45 seconds allowing the carbon from the paper to penetrate the unglazed parts.
Vapor glaze or (Kosai) which means "hue of light".  The effect, unlike raku, is archival.  The colors will never fade.  Glazes, lusters, and surface treatments of these pieces are created from multiple firings to produce the desired iridescence by the vapor glazing process.