Raku Firing And Horse Hair Technique A Comprehensive Guide Using A Regular Kiln
Raku firing is an exciting and unpredictable pottery firing technique that originated in 16th-century Japan. Known for its dramatic effects and unique finishes, raku often involves rapidly firing and cooling pottery, resulting in metallic sheens, crackled glazes, and blackened clay. While traditionally performed in specialized raku kilns, it's entirely possible to achieve stunning raku effects using a regular kiln, particularly when incorporating the horse hair technique. This article delves into the process of raku firing in a standard kiln, focusing on the intriguing horse hair technique, while providing a comprehensive guide for pottery enthusiasts.
Understanding Raku Firing
Raku firing techniques offer a distinctive departure from conventional ceramic firing methods. The traditional raku process involves removing pottery from the kiln while it's still glowing hot—typically around 1800°F (980°C). The pieces are then placed in a container filled with combustible materials such as newspaper, sawdust, or leaves. This creates a reduction atmosphere, where oxygen is rapidly consumed, influencing the glaze colors and causing unique effects. The sudden temperature change and the reduction atmosphere are the core elements that give raku pottery its signature look.
Raku's appeal lies in its unpredictability and the immediate, hands-on nature of the process. Unlike standard kiln firings that can take many hours or even days, raku firings are quick, often completed in just a few hours. This rapid turnaround allows potters to experiment and see results almost immediately, fostering a dynamic and engaging creative process. The imperfections and surprises inherent in raku firing are embraced as part of the art form, making each piece truly one-of-a-kind. The crackle glazes, metallic flashes, and smoke-infused surfaces are highly prized by collectors and artists alike.
The reduction atmosphere plays a crucial role in the final appearance of raku pottery. When oxygen is deprived, the metallic oxides in the glazes react differently than in an oxidation firing. For example, copper-based glazes can turn a vibrant metallic copper, and other glazes may develop lustrous sheens or dark, smoky hues. This chemical transformation is what gives raku its distinctive and often iridescent qualities. The combustible materials in the reduction chamber not only create the necessary atmosphere but also contribute to the aesthetic by depositing carbon onto the pottery surface, enhancing the contrast and adding depth to the design. This interaction between fire, smoke, and glaze is where the magic of raku truly happens.
Adapting Raku for a Regular Kiln
While specialized raku kilns are designed for rapid heating and cooling, using a regular kiln for raku firing requires some adjustments and precautions. Regular kilns are typically built for slower, more controlled temperature changes. However, with careful planning and execution, it’s possible to achieve raku effects safely and effectively.
Modifications and Safety Measures
One primary concern when using a regular kiln for raku is the potential thermal shock from rapid temperature changes. To mitigate this, it's essential to heat the kiln more gradually than you would in a dedicated raku firing. A slower ramp-up and ramp-down in temperature will help prevent cracking and damage to both the pottery and the kiln itself. It’s also crucial to ensure adequate ventilation, as raku firing produces significant smoke and fumes. If firing indoors, use a well-ventilated space or a kiln vent system to remove harmful gases. Safety gear, including heat-resistant gloves, a face shield, and tongs, are indispensable when handling hot raku pottery.
Firing Schedule
A typical raku firing schedule in a regular kiln might involve a slow initial heating phase, reaching a temperature of around Cone 06 (1855°F or 1013°C). This slow climb helps to prevent thermal shock. Once the desired temperature is reached, the kiln is held at that temperature for a short period to ensure the glazes have fully melted. Then, the kiln is turned off, and the door is carefully opened slightly to allow for a more rapid cooling process. This controlled cooling, while not as abrupt as in traditional raku, still imparts the thermal shock necessary for the raku effects. Remember to monitor the kiln closely during this phase to prevent any extreme temperature fluctuations that could damage the pottery or the kiln.
Reduction Chamber Setup
Creating a reduction chamber is a critical step in raku firing. This can be as simple as a metal container filled with combustible materials. The container should be large enough to hold the pottery with ample space for the materials to ignite and create the smoky atmosphere. Common materials include sawdust, newspaper, wood shavings, and dried leaves. The pieces are transferred hot from the kiln to this chamber, immediately igniting the combustibles and creating a reduction environment. The duration the pieces remain in the reduction chamber affects the final outcome, with longer times typically resulting in more pronounced effects. Experimentation with different materials and timings is key to mastering the art of raku.
The Horse Hair Technique
The horse hair raku technique is a captivating method for adding unique surface decorations to pottery. This technique involves applying strands of horse hair directly onto the hot ceramic surface immediately after the piece is removed from the kiln. The intense heat causes the hair to combust, leaving delicate carbon tracings and intricate patterns on the pottery.
Preparing the Pottery
For the horse hair technique, the pottery should be bisque-fired as usual. Then, apply a raku glaze to the piece. A white or light-colored glaze is often preferred as it provides a stark contrast to the dark carbon markings, making the patterns more visible. However, experimenting with different glaze colors can yield interesting and unique results. Ensure the glaze is applied evenly and allowed to dry thoroughly before the raku firing.
Firing for Horse Hair Raku
When firing specifically for the horse hair technique, the pottery should be brought to a temperature where the glaze is molten but not overly fluid. This typically corresponds to Cone 06 (around 1855°F or 1013°C). Monitor the kiln closely and use witness cones to ensure the temperature is accurate. Once the desired temperature is reached, carefully remove the pottery from the kiln using tongs and place it on a non-combustible surface, such as a brick or metal sheet.
Applying the Horse Hair
This is where the magic happens. While the pottery is still glowing hot, take small strands of horse hair and carefully lay them across the surface. The heat will instantly ignite the hair, causing it to burn and leave a carbon residue on the glaze. Different patterns can be achieved by varying the amount of hair used, the way it’s applied, and the direction in which it’s placed. For finer lines, use thinner strands of hair; for bolder marks, use thicker clumps. The burning process is quick, so you’ll need to work efficiently but carefully.
Cooling and Finishing
After applying the horse hair, allow the pottery to cool naturally. The cooling process affects the crackle patterns in the glaze and the overall appearance of the carbon markings. Once the piece is cool enough to handle, you can gently wash it to remove any loose ash and reveal the final design. The carbon tracings will be permanently embedded in the glaze, creating a striking and unique pattern. Sometimes, a clear sealant can be applied to further protect the surface and enhance the contrast of the design.
Tips for Success
Glaze Selection
Choosing the right glaze is crucial for successful raku firing and horse hair decoration. Raku glazes are specially formulated to withstand the rapid temperature changes and reduction atmosphere inherent in the process. These glazes often contain metallic oxides, which react dramatically in the reduction environment, producing lustrous sheens and vibrant colors. For the horse hair technique, a glaze that melts smoothly and provides a good surface for the carbon to adhere to is essential. White or light-colored glazes are popular choices because they offer a clear backdrop for the dark carbon markings, but don’t hesitate to experiment with other colors to achieve different effects.
Hair Preparation
The type and quality of horse hair used can affect the outcome of the technique. Clean, dry horse hair works best. You can gather horse hair from a variety of sources, including grooming brushes, stables, or even online suppliers. Experiment with different lengths and thicknesses of hair to see how they affect the patterns. Some artists even use other types of hair, such as feathers or plant fibers, to create unique textures and designs.
Safety First
Raku firing involves high temperatures and potentially hazardous materials, so safety should always be a top priority. Wear heat-resistant gloves, a face shield, and protective clothing to prevent burns. Ensure the firing area is well-ventilated to avoid inhaling harmful fumes. Keep a fire extinguisher nearby and be prepared for potential flare-ups. When removing pottery from the kiln, use long tongs to maintain a safe distance from the heat. Always exercise caution and respect the power of the firing process.
Experimentation
One of the joys of raku firing is the opportunity for experimentation. There are countless variables that can influence the final result, from the type of glaze and the firing temperature to the combustible materials and the cooling process. Don’t be afraid to try new things and push the boundaries of the technique. Keep a detailed record of your firings, noting the materials, temperatures, and techniques used, so you can learn from your successes and failures. The more you experiment, the better you’ll understand the nuances of raku firing and the horse hair technique.
Conclusion
Raku firing, particularly when combined with the horse hair technique, offers a rewarding and creative outlet for pottery enthusiasts. While traditionally associated with specialized kilns, achieving stunning raku effects in a regular kiln is entirely feasible with careful preparation and execution. The horse hair technique adds an extra layer of artistry, resulting in unique, organic patterns that make each piece a true work of art. By understanding the principles of raku firing, prioritizing safety, and embracing experimentation, you can unlock the full potential of this captivating ceramic process. So, fire up your kiln and let the magic of raku transform your pottery into extraordinary creations.
