Each Raku piece is unique, the product of a complex firing process that tests the integrity of the form.
Sen no Rikyū, the 16th century Japanese tea master, developed the Raku firing process for tea ceremony bowls. Each piece is individually fired and reflects the specific conditions of that moment.
Raku pieces are considered “spiritually whole” since the firing process includes all the states of nature - earth, fire, air and water.
Earth - the clay that becomes the pot
Fire - the firing process that brings the clay to life
Air - feeds the fire and matures the glaze and the clay
Water - rapidly cools the pot and reveals any flaws in the piece
The Raku process is now popular around the world. It was brought to the United States in the 1950s.
Steps in the Raku Process
The piece is formed, dried, then bisque fired, which makes the clay ready to accept the glaze. Raku glazes are formulated to work at particular temperatures and to mature in a reduction atmosphere. Once glazed, the piece is put in a kiln and heated to about 1900 degrees Fahrenheit. At this temperature the clay is glowing hot and has sheen that indicates it is ready to be removed from the kiln.
The piece is removed (very carefully!) and put in a container with flammable material - such as a metal trash can with paper, straw and sawdust. The container is then closed, in this case by putting the lid on the trash can, to create the reduction atmosphere. The fire consumes the oxygen, even pulling oxygen from the clay and the glaze. This is how the glaze matures. Without a source of air the fire will burn itself out.
While still hot, the pot is removed from the can and submerged in water. This last thermal shock sets the glaze and if there is a flaw in the piece it will crack. If there is no crack, the piece has survived the Raku process and is considered spiritually whole.
Using Your Raku Piece
Always hand wash your Raku piece.
Raku is not entirely watertight. If you are using a vase it could “sweat” so put it on something that can get wet.
Glazes are food safe but could be very hard to clean. Ask if your Raku piece is appropirate for food use.