For experienced potters and those just beginning to explore the ancient art of clayworking, firing the clay is an important step in the process. Kilns – furnaces capable of reaching very high temperatures – are traditionally used to fire clay. However, if you don’t have a kiln, there are a few alternative methods available to you. From outdoor pits and open fires to creating your own soda kiln, let’s take a look at the types of non-kiln clay firing techniques you can use.
Types of Non-Kiln Clay Firing Techniques
Rather than using a standard kiln, outdoor firing techniques allow you to use natural elements as fuel. There are several different types of alternative firing you can do without a kiln, each of which will create unique effects on the finished piece. Here’s a rundown of some of the most common types of non-kiln filing.
Raku firing is a popular technique that involves removing the piece from the kiln while it is still hot and placing it in a container with combustible materials. This creates a smoky atmosphere that can give the piece a unique finish. Pit firing is another technique that involves burying the piece in a pit filled with combustible materials and then lighting it. This can create a range of colors and textures on the finished piece.
Building an Outdoor Pit
Outdoor pits are one of the most traditional ways to fire clay without a kiln. This method involves burning wood or other combustible material to create an intense fire in a shallow pit in the ground. If desired, you can also add combustibles to the fire as it burns in order to regulate the speed and intensity of the flames. As the fire burns down, cover the pit with a thick layer of sand or dirt to insulate and regulate the temperature of the fire.
Using An Open Fire to Fire Clay
The open fire method of firing clay involves safely building and maintaining an outside fire in an area that won’t pose a hazard to you or your surroundings. Typically, a mixture of crushed glass, sawdust, and combustible materials such as newspaper and cardboard are placed in an open fire. The combustible elements will create an intense flame, and pieces of clay should be placed securely in position in the direct path of the flame for firing. This method won’t achieve extremely high temperatures without prolonged exposure to the flames.
The Soda-Firing Technique
The soda-firing technique is a type of atmospheric firing that uses sodium bicarbonate – baking soda – during the firing process in order to achieve unique effects on the glazed surface of the piece. As the firing progresses, sodium bicarbonate is placed on the edges and surface of the piece, which produces a characteristic mottling effect on the clay. As with the open fire method, temperatures achieved with this technique are not as high as those reached with a kiln.
Raku Firing Clay
Raku firing is a popular firing technique used by many potters. This method involves creating intentionally thick walls on a piece and using combustibles such as newspaper, wood, or sawdust in order to increase the speed and intensity of the fire. Raku pieces are fired to temperatures between 1600 and 1800 degrees Fahrenheit before being quickly removed from the fire and compressed with a lid or other covering. As with soda firing, special effects can be achieved through this method.
Pit Firing Clay
Pits are one of the oldest methods used to fire clay, with written accounts of pit firing dating back to ancient civilizations. To pit fire your pieces, dig a shallow pit and cover it with combustible materials and pieces of clay resting on top. Place additional combustible materials such as newspaper, straw, and wood around the pieces and set the whole thing alight. Once the flame has died down, cover the pit with sand or dirt and allow it to naturally cool.
Safety Considerations for Non-Kiln Firing Techniques
When using any type of non-kiln clay firing technique, it’s essential to practice safe working habits. Clear away any flammable material from the perimeter of your work area, practice proper ventilation techniques, wear protective gloves and clothing, and never attempt to fire pieces without adult supervision.
Potential Benefits for Non-Kiln Clay Firing
Non-kiln clay firing techniques can offer a number of potential benefits compared to traditional kiln-firing methods. For one thing, some techniques such as raku and pit firing can be quicker and more spontaneous than firing in a kiln. Plus, as mentioned above, these techniques can also produce unique colors and effects on the surface of your pieces. Finally, non-kiln firing can be much more affordable than firing in a traditional kiln.
Troubleshooting Common Issues with Non-Kiln Clay Firing
In some cases, you may run into issues when firing your pieces without a kiln. One issue that often arises is warping due to uneven heating. To attempt to remedy this issue, consider using an insulated pit or covering your piece with insulation material prior to firing. Additionally, some pieces may benefit from attention in post-firing; for example, poorly-fitting lids may need adjustment before use.
All in all, firing clay without a kiln is certainly possible but should be done cautiously and with plenty of research first. By understanding the different techniques available and taking the necessary precautions, you should be able to achieve great results with non-kiln clay firing.
