What is Raku Pottery?
Raku pottery is created with a specific ceramic firing process that uses both fire and smoke to create unique patterns and designs. The piece is first bisque fired, then it is glazed and undergoes a raku firing process. The firing process requires a special raku kiln that is fueled by propane and reaches temperatures of about 1,800°F (about 982°C).
In order to complete the firing process, the pottery must remain in the kiln for approximately 30 minutes. It is then removed from the kiln using specially designed raku tongs. While the raku pottery piece is still hot and glowing, it is placed inside a metal can full of combustible materials. The heat emitted from the pottery causes these materials to catch on fire.
After the materials inside the metal can catch on fire, a lid is placed over the can and the pottery is sealed inside. The piece is capable of withstanding these high temperatures and the fire within the can because it is made from a special type of clay that is capable of withstanding thermal shock. Traditional pottery clays, on the other hand, would crack from the drastic temperature changes.
As the fire consumes the oxygen within the can, it also draws the oxygen out of the pottery and its glaze. This process is called post fire reduction. It this stage that creates the unique look of raku pottery. The resulting patterns and colors are unpredictable, as they are created through the natural process of oxygen removal.
After the raku pottery remains in the sealed metal can for about 15 minutes, it is removed and placed in a can of water. This freezes the patterns that were created during the post fire reduction stage. The amount of time a piece should remain in the cooling water largely depends on the piece and its size.
Because the process of creating this pottery requires working with combustible materials and high temperatures, it is important for craftspeople to wear gloves, protective clothing, and eye protection at all times while creating a new piece.
Just to clarify, this is American raku or Paul Soldner's technique. It is not traditional Japanese raku.
I just had two items appraised: a large brown vase with a lid and a vase without a lid. Whey said the large vase was over 400 years old and quite valuable. Who can I contact about getting more info about these items?
How do you care for the raku pottery?
Having done Raku for a number of years, I know it is quite common to glaze, fire and cool a Raku pot within the span of a couple hours with great results.
A lot of the success comes from knowing the kiln, clay body and glazes and how they interact together, coupled with a fair degree of trial and error. Even then, time of day, moisture in the air, sawdust verses newspaper during reduction, etc, can effect the overall outcome.
It's the "surprise factor" that makes Raku such an interesting art form.
I am uncertain if I have learned anything or not.
I was really questioning whether Raku was a process/technique, if it was referring to the materials used, or both. Still don't know.
I was really interested in reading this article until I got to the part about raku being done with a propane fueled kiln. Raku has been around for four or five centuries. Last I checked, they weren't using propane kilns back then.
I have several raku pieces which I would like to place in our garden for the summer. What outdoor temperature can they withstand? I am concerned about low temperatures.
I have put hot raku from a wood kiln to a pail of water-incredibly dramatic, but apparently safe and effective!
Although I agree with Mr.Reply#1 that some information is incorrect in the text (traditionally earthenware was used; Raku refers to the name of a family of Japanese potters from 16th Kyoto who created the style, the distinctive characteristics being low-temperature and interrupted firing; obviously at that time they did not have access to propane kilns, their firing was fueled with wood; Raku doesn't necessarily imply "smoking", i.e. putting the ware in a reducing combustion atmosphere, as some potters simply left it to cool or..) that indeed it was quenched in water - and still is by some potter, one in Hagi that I know of.
Raku doesn't automatically relates to reducting combustion, just low-firing and interrupted firing. One must keep in mind that Raku was first the name of a family of potters, as mentioned, no a technique. Their own style became a style of its own, but it doesn't define a precise technique.
Besides, there is no "correct" way to do Raku ;-)
Some of your information about firing Raku is incorrect. First, any claybody can be used in the raku process. I use a regular hobby low-fired ceramic slip.
You don't need to pull the piece from the can after 15 minutes. This is dangerous because the can could flair up when the oxygen hits it. I leave the piece in the can for an hour and pull it from the can while it is cool.
Putting a hot piece of raku in water will never be a good thing. The colors will set as the piece cools in the can and water will only crack the piece and moisture if left in the piece will ruin the colors. There are way too many people doing raku the wrong way and not getting very good results.
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