Written by Cidinha Moss with the collaboration of Peter Bright, who kindly assessed and revised it. All photos are courtesy of the artists.
Explore the Unpredictable and Excitement of Raku Pottery
Raku is a low-fire process where pottery is removed from the kiln when red hot and cooled rapidly in combustible material like sawdust or newspaper. This type of firing is usually done in a fuel-burning outdoor brick kiln, not an electric one, and reaches temperatures of around 1000°C.
Our comprehensive beginner’s guide to raku pottery provides a thorough exploration of techniques and ceramic glazing, including Obvara methods and essential tips crucial for mastering the ancient art of raku firing.
This article will help you unlock your creative potential with our detailed step-by-step approach to raku firing. You’ll soon be a convert and understand why everyone is so thrilled about raku.
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Brief History of Raku
Raku pottery is a unique form of low-fired pottery technique that has captivated artists and collectors alike for centuries with its unique blend of simplicity and elegance. The term “raku” itself holds a profound meaning, translating to “enjoyment, pleasure” in Japanese, reflecting the joy and satisfaction that comes from creating and appreciating this art form.
The journey of raku pottery began in Korea in the 16th Century, when potters first experimented with low-fired techniques to create pottery with a distinct charm. However, it was the Japanese potters in the Momoyama period (1573-1615) who refined the fast-firing process and elevated raku pottery to new heights. The Japanese embraced the imperfections and spontaneity of raku, viewing them as integral to the beauty of the finished pieces.
Over time, raku pottery gained popularity not only in Japan but also across the globe. One of the first pioneers to introduce the raku firing process to the Western world was the renowned English potter Bernard Leach. In 1911, while living in Japan, Leach became captivated by the beauty and simplicity of Raku pottery. He studied the techniques and traditions of Japanese pottery and later incorporated them into his own work, helping to popularise raku in the Western art world.
The appeal of raku pottery lies in its organic and unpredictable nature. Each piece is a one-of-a-kind creation, shaped by the hands of the artist and the whims of the fast-firing process. The crackled glaze, smoky patterns, and irregular shapes of raku pottery reflect the philosophy of wabi-sabi*, embracing imperfections and impermanence as essential elements of beauty.
(*) Wabi Sabi = The Beauty in Imperfection. Wabi can be interpreted as “tranquil simplicity” and sabi as “patina or rust,” referring to the beauty that comes with age and wear from continuous use.
Eastern Style Raku Firing
The history of raku pottery is a testament to the enduring appeal of this ancient art form. From its humble origins in Korea to its transformation and adaptation in Japan and the West, raku pottery continues to inspire and enchant with its beauty, simplicity, and profound sense of enjoyment.
Eastern raku firing uses shorter firing cycles, sometimes as brief as 15 to 20 minutes, undergoing a rapid cooling in open air or immersed in water for cooling.
Western Style Raku Firing
In the Western world, raku pottery quickly gained a following among artists and collectors for its distinctive aesthetic and cultural significance. The process of creating raku pottery involves not just skill and technique but also a deep connection to the materials and the elements. The act of firing the pottery in an outdoor kiln, surrounded by the crackling flames and the scent of burning wood, becomes a ritual of creativity and contemplation.
Today, raku pottery continues to captivate artists and art enthusiasts around the world, with workshops and studios dedicated to preserving and celebrating this ancient craft. The fusion of Eastern tradition and Western innovation has led to a diverse range of styles and interpretations of raku pottery, each reflecting the unique vision and passion of the artist.
In the Western Raku Process, a secondary reduction was introduced, subjecting the pot to a combustible material. In this reduction, by depriving the atmosphere around the pot of oxygen, the clay body becomes blackened and produces unique, surprising effects in colour variations on the clay body. The pots are then taken out of the reduction box and plunged into water for rapid cooling.
The Volatile Raku Firing Process – What Is Raku Firing?
The Raku firing process starts with the creation of pottery pieces. Initially, the clay is expertly shaped. Following this step, the items undergo bisque firing in a kiln to eliminate any residual moisture and enhance the durability of the clay body. Once they have been successfully bisque-fired, the pieces are prepared for glazing. All raku pottery is delicate and has a porous structure, making it unsuited for practical use.
The elements of raku firing process:
Clays
The clay you use must contain enough grog or sand to endure the thermal shock associated with raku firing and rapid cooling. An appropriate quantity of grog or sand will mitigate both shrinkage rates and the effects of thermal shock during the raku firing process.
The colour of your clay significantly influences its interaction with compostable materials, the reduction chamber, and glazes. Darker clays tend to produce more subdued tones, while lighter clays generate brighter hues. Your colour selection should align with the artistic effect you wish to achieve and the specific reactions you desire from your raku glaze surface.
It is recommended that you make use of raku clays that have been specifically manufactured by most suppliers. You have the freedom to create raku pots in whichever manner you prefer. Whether you decide to throw, cast, or handbuild them, aim for uniform thickness and minimise joints. Keep in mind that any poorly executed join will become a weak point susceptible to thermal shock. Bisque fire your pots in the cone 010 to cone 04 range (900 – 1050 °C).
Glazes
The next step is applying raku glaze to your ceramic pieces. Glazing can often seem intimidating, but approach it with assurance and confidence, as any uncertainty will be evident. We suggest beginning with a single glaze base and using it to create a range of colours by incorporating stains and oxides. This approach will help minimise the occurrence of mismatched glazes across different types as they mature. Be aware that the stains may experience some loss of colour in reduction environments.
Raku Glaze
The glazes used in the raku process must be low-temperature or raku glaze, which has a low melting point. Raku glazes must maintain stability at lower temperatures while offering a variety of colour and texture variations when subjected to rapid cooling following removal from the kiln. Some glazes offer a nice crackle effect or you can add stains to create a unique look.
You can use reliable commercial raku glazes or your own for the raku firing process. In our group, we use both commercial and dedicated homemade prepared raku glazes. If you want to make your own, there are numerous recipes available. Look on the internet, consult any glazes or raku books, and ask knowledgeable friends. You can mix your own, but remember you will need the proper supplies, mixing equipment, and knowledge. Â
Applying the Glazes
You can use every technique imaginable to apply glaze to raku, including dipping, pouring, brushing, spraying, splashing, dripping, sponging, and every other kind of application imaginable. You can use glazes by themselves or mix them with different materials. Remember that the outcome is directly influenced by how you apply the glaze.
The thickness of the glaze affects its colour. For a glaze to exhibit a colour, it needs to be applied with a thickness of 3-4 ml. During the firing process, it transforms into glass, with only a small portion of its total volume—approximately one-twentieth—comprising colouring agents.
The glaze will fire unevenly across your pieces. It tends to melt first at the rim and last on the inner bottom, which means you need to arrange the pots in the kiln in a way that allows you to evaluate their maturation visually by observing multiple surfaces.
Be aware that the parts that remain unglazed or covered with wax resist will turn black due to the carbon released during the reduction process.
Most raku firing will be in the cones 010 – 06 range (low fire). Raku firing can occur in both oxidation and reduction environments, though it typically is in reduction as the rapid firing consumes oxygen. Variations in temperature within the kiln will have an impact on the finished piece. Generally speaking, low-temperature firings tend to produce satin matt glazes and soft hues, while higher temperatures yield brighter and more translucent colours.
Kilns
Two kilns are going to be used in the raku process. The first is for the bisque fire. The second is the raku kiln used for the raku firing process. Due to the rapid firing process and the lower temperatures utilised in raku firing, gas-fired raku kilns are generally more cost-effective to operate compared to other kilns. When you are firing, cover as much of your body as possible and never wear polyester or similar for obvious reasons.
As glaze maturing is determined visually, leave enough space when you position your pots in the kilns to check maturity (wet and reflective) and easy removal with tongs. You can use a pyrometer, but do not rely solely on it. Often, you will need to soak (maintain but not increase temperatures) to fuse the glaze evenly on the piece.
Post-Firing Reduction
When you remove your objects from the kiln, you will be doing what is called postfiring reduction. In this stage, you will be placing your red-hot pots in combustible materials—like dry leaves, grass clippings, sawdust, or newspaper—outside of the kiln within a closed environment, such as a metal garbage bucket.
In the post-firing reduction process, the low oxygen and free carbon surface areas will alter the clay’s colour to shades of grey or black. Additionally, glazes that include copper might acquire a shiny finish, which can be polished.
Timing is essential in this stage. Remove your pots from the kiln and place them on a non-flammable surface. Within seconds, you will see cracks forming as lines on the glaze. Using tongs, carefully pick them up and place them into your container filled with combustibles. Allow it to catch fire before quickly covering it. Leave them for 30 minutes – 1 hour in this oxygen-free atmosphere.
Then, immerse in water to cool, clean your pots with metal pot scrubbers and marvel at the colours and textures you have created.
Tools
Other important raku firing material you will need to complete the raku process:Â
- Long metal Tongs – To safely remove red-hot pottery from the kiln. We recommend selecting metal tongs with a minimum length of 90 centimetres for optimal safety and functionality.
- Safety Gear Equipment – For the firing process, it is essential to wear a pair of heat-resistant gloves and UV protection safety glasses. If you have longer hair, don’t forget to grab a hair tie or clip!
- Reduction Chamber – Use a garbage metal bucket or another form of fireproof container for your reduction chamber. Smaller trash cans or metal containers are often favoured as they provide better control over the pots. Your chosen container must be equipped with a fireproof lid to ensure safety during operation.
- Combustible Materials – Newspaper is often used, but make sure it is not a glossy or shiny paper. You can use other organic combustibles such as dried fruit or vegetable peelings, sawdust, dry leaves, branches, hay or woodchips.
Understanding How the Raku Process Works
In contrast to conventional fire, which can take up to twenty-four hours, raku firing only takes about one or two hours. As we mentioned before, the first step in the process is to glaze your bisque pieces with raku glaze. These raku glazes are engineered to melt at cone 06 in approximately one hour because of their low melting point.
Following this, add your goods to the kiln and wait for it to reach a temperature of 1000 °C. If everything is going according to plan, after 45 minutes of fire, check on the ware every 15 minutes. You can tell it’s working if you see bubbles forming in your glaze. To continue to the following step, wait another 15 minutes once you see the glaze bubbling on the ware.
When the pottery is red-hot…
When the pottery is red-hot and the glaze is glossy and liquid, it is time to take it out of the kiln. While you are waiting for the firing to finish, you can get your recipient ready to reduce the oxygen content of the item. We used garbage metal buckets with sawdust or shredded newspaper. One hint is to make sure the containers are somewhat larger than the items you intend to store in them. The narrower the space is around the object, the more effectively oxygen is reduced, leading to a more vibrant range of colours.
For the best results, we used three persons to handle the components of the raku process. One person opens the kiln door when the pieces have reached a red-hot glow. Another transfers the pieces from the kiln to the metal container using tongs, and a third seals the lid. At this stage, you should be wearing protective gear because you are handling extremely hot items.
To maintain the necessary heat as the pot is being removed from the kiln, close the kiln lid between each piece being removed. To keep the heat, put the pieces into the waiting buckets as soon as you can. Wait for the sawdust or newspaper to catch fire, then cover the pot immediately to create unique reduction effects.
The next step is to give the pieces 30 minutes to an hour to wait for the effects to kick in.
Carefully remove the lid; the smoke is quite hot and could burn your face if you aren’t careful. Remember, the pieces are still very hot. For the post-firing reduction, use a bucket of water to chill the pottery by pouring it on top, then removing individual pieces with tongs and submerging them in the water.
At this stage, you should be able to observe the wonderful effects the raku firing has produced on your pot.
The Cleanup of the Artwork
After the artwork has cooled, it is essential to clean it thoroughly. Although one might be inclined to view soot and smoke residue as integral components of the glaze finish, it is important to note that this sooty film is not permanently affixed to the piece and can be removed.
The black carbon that has penetrated the pores of the clay body is effectively permanent and cannot be removed through washing. To eliminate the soot accumulation produced during the firing, it is recommended to gently scrub the surface using a non-woven abrasive while immersed in water, either in a sink or bucket.
Further Exploration: The Obvara Firing Process
The Obvara firing process, sometimes called Baltic Raku, originated in Eastern Europe around the 12th Century. It involves scalding the finish on the pottery to seal the porous surface. Similar to the raku pottery process, a bisque pot is heated to 900°C and removed from the heat.
Peter Bright, our pottery tutor with many years of experience and knowledge, has been encouraging us to learn more about this unique firing technique, which produces stunning and unpredictable results. Ovbara is a firing process that employs ingredients that are typically used in the production of bread.
Obvara is essentially carbon discolouration, which provides ceramic surfaces with spontaneous decoration. Each wheel-thrown or hand-built pot is finished with this procedure, resulting in visually appealing surfaces that possess their own distinctive characteristics.
Obvara Mixture Recipe:Â Â
- Mix 9.8 litres of water
- 1 Kg of flour
- 1 tablespoon of sugar
- 2 packets of yeast.
Allow the mixture to ferment for about 3 days, stirring frequently.Â
The Obvara Technique
Before experimenting with the Obvara firing, quite a lot has to be done. Each piece has to be thrown and bisque fired. In the Obvara technique, your piece of pottery is taken from the kiln and promptly submerged in a fermented solution composed of water, flour, yeast, and sugar. This process causes the surface of the pot to become scalded, resulting in a striking array of colours ranging from creamy tans to rich browns and blacks. It is important to note that, similar to other low-temperature alternative firings, Obvara pieces are intended solely for decorative purposes and should not be used for food or liquid containment.
The Obvara technique produces unique and different effects. While certain elements can be manipulated, a significant portion of the outcome is influenced by variables beyond our control. This unpredictability is one of the many aspects that makes raku firing such an exhilarating experience.
Whether you are a beginner or an experienced potter, understanding the Obvara firing process can add a new dimension to your work and elevate your pottery creations to new heights.
The Enduring Significance of Raku Pottery
The activity’s intrinsic social element is an additional and crucial feature to highlight. Raku, as a trial by fire, does wonders for studio camaraderie, merging the beauty of this volatile, unpredictable blend of artistry with the enhanced creativity it promotes in our studio group.
The fast and furious raku firing technique is certainly a distinctive social experience. Rapid and exhilarating, it requires the assistance of friends, and it delivers immediate outcomes that are truly unique.
Raku is all about embracing imperfection and being unpredictable. Every piece exemplifies the idea of ‘pleasure in the accident,’ where the outcome is determined by chance and the specific firing conditions. The unique style, the randomness of each piece, and the profound philosophical ideas it conveys all contribute to its appeal. The modern world finds inspiration and evolution in this creative form, which ensures its relevance.
Conclusion
To wrap it up, raku glazing is more than just a cool art vibe—it’s like a fun mix of science and creativity all rolled into one. When you check out those amazing raku-glazed pieces, think about the crazy dance of molecules and the wild back-and-forth that happens during the firing process to make each piece pop. Raku glazing shows off how tech skills can mesh perfectly with artistic flair, taking ceramics to a whole new level where science and art really come together in style.
Are you ready to create Something Spectacular?
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