Pottery making - Raku and Pit fire techniques

Ceramics is a versatile and expressive art form, The last few classes of the current session of my ceramics course Vrije Academie Maastricht were an enriching and memorable experience full of experiments and surprises. I learned Raku and Pit fire techniques. Both require different kinds of clay and different firing methods. The best part was the final day when together with my colleagues we went to our teacher Natascha Rieter 's art studio to do the firing. Safety precautions, such as handling the fire, flames, and smoke, were emphasized to ensure everyone's well-being. She showed us the tools and equipment used for firing and then we prepared for the fire. It was a very robust and visually striking thing to see burning hot fire, flames, and smoke, Observing the pots burning red hot was a captivating sight. The transformation of the clay as it undergoes the firing process is truly remarkable.

Raku and pit firing are two distinct pottery techniques that offer an element of surprise and unpredictability. These techniques create distinctive and unconventional surface effects, making them popular among ceramic artists seeking experimental and expressive outcomes.

Raku Firing is a traditional Japanese technique that originated in the 16th century. It is characterized by rapid firing and cooling processes, which result in distinctive and often dramatic surface effects. First, the pottery piece is bisque fired to a low temperature to remove any moisture. It follows by glazing that typically contains a high percentage of low-fire materials, such as frits, oxides, and colorants, that produce vibrant colors and unique crackling effects. The glazed piece is then placed in a small, fuel-fired kiln and rapidly heated to around 1000°C. Once the glazes have reached maturity, the piece is quickly removed from the kiln using tongs and placed into a reduction chamber, such as a metal container filled with combustible materials. The reduction chamber is sealed to restrict oxygen, creating an oxygen-starved environment. The combustible materials catch fire and produce smoke, which interacts with the glazes, causing reduction reactions. This process creates metallic and iridescent effects on the glazed surface. After the reduction process, the piece is removed from the reduction chamber and allowed to cool in the open air, alternatively, it can be plunged into a container of water. The thermal shock and cooling process create further crackling and color variations on the pottery surface.

Pit firing is an ancient firing technique that predates pottery kilns. The pit firing process is relatively straightforward. The pottery pieces are made from clay and dried thoroughly. They are then burnished with stones to create a polished surface and coated with copper and iron oxides for producing colors. A container is filled with sand and wood, lined with sawdust, newspaper, and other combustible materials. Pottery pieces are placed inside the pit, surrounded by organic materials, such as wood shavings, leaves, or sawdust. The pit is set on fire, and the flames are allowed to burn and envelop the pottery pieces. The fire's heat and smoke create an oxidizing or reducing atmosphere, depending on how the fire is managed. The process can take several hours to reach the desired temperature. Once the firing is complete, the pit is left to cool naturally. The pottery is usually covered with ashes, which can contribute to unique surface patterns and colors. When the pots were still hot, horsehair was scattered on the surface to produce design effects. After cooling, the pottery pieces are carefully taken out from the pit and cleaned to remove any residue. In the end, a protective wax was applied to make the surface shiny.?