Understanding Firing Processes

Firing is one of the most crucial steps in the ceramic-making process. It transforms soft clay into durable, finished pottery. At Chester River Pottery, we take great care in each stage of firing to ensure that our pieces are both functional and beautiful. In this post, we’ll explore the two primary stages of firing—bisque and glaze firing—and discuss the different types of kilns used for each process.

Bisque Firing: The First Transformation

Bisque firing, also known as the first firing, is a process that removes all residual moisture from clay and hardens it into a porous yet sturdy state. Typically, bisque firing occurs at lower temperatures, ranging from about 1730°F to 1940°F (cone 06 to cone 04). This stage is crucial because:

• It expels any remaining water, preventing pieces from exploding in the kiln.
• It makes the pottery strong enough to handle yet still porous enough to absorb glaze effectively.
• It incinerates organic material and chemically binds the clay particles, enhancing the piece’s durability.

At Chester River Pottery, we utilize both electric and gas kilns for bisque firing, each presenting unique advantages. Electric kilns offer precise temperature control, whereas gas kilns can produce subtle variations in surface texture due to their atmospheric influences.

Glaze Firing: The Finishing Touch

Glaze firing is the second firing where a thin layer of glaze applied to bisque ware melts into a smooth, glass-like surface. This firing occurs at a higher temperature, typically ranging from 2165°F to 2381°F (cone 5 to cone 10), depending on the type of glaze and clay body. This process:

• Seals the pottery to make it non-porous and safe for food.
• Enhances colors and textures, resulting in a glossy, satin, or matte finish.
• Enhances the piece by further vitrifying the clay body.

Gas and wood-fired kilns are often favored for glaze firing due to their capacity for greater atmospheric interaction, which influences glaze effects in distinctive and unpredictable ways. In contrast, electric kilns provide controlled and consistent outcomes, making them ideal for achieving specific finishes.

Choosing the Right Kiln for the Job

Different kilns create different effects, and each has its advantages:

• Electric kilns offer reliable, consistent results with accurate temperature control.
• Gas Kilns: Create atmospheric variables that produce unique glaze effects and richer surface textures.
• Wood-Fired Kilns: This is the most traditional method that produces natural ash glazes and unique color variations.

At Chester River Pottery, we enjoy experimenting with different firing methods to create unique results, merging tradition with modern techniques.

Final Thoughts

Understanding the differences between bisque and glaze firing helps both potters and collectors appreciate the complexity behind every ceramic piece. Whether you’re a beginner learning the craft or an enthusiast admiring completed works, these firing processes provide pottery with its strength, beauty, and character.

Stay tuned for more insights into our pottery-making techniques, and we invite you to visit our studio to witness the firing process in action!

You can continue the journey by subscribing to “All Things Ceramic,” our monthly newsletter, or arrange a Virtual Visit to discuss your custom pottery ideas.