Must Knows for K-12 Teachers Firing Electric Kilns!

Working with clay is one of the most rewarding hands-on experiences for students. From shaping their first pinch pot to seeing a finished piece come out of the kiln, the process combines creativity, science, and patience. If you’re new to ceramics—or just need a refresher—here are the essential things every K–12 classroom should know about using clay and firing kilns safely and successfully.

1. Understanding Cones: Low Fire, Mid Range, and High Fire 

When working with clay, one of the most important concepts to understand is firing temperature. In ceramics, we don’t just talk about temperature in degrees—we also use something called cones to measure heatwork inside the kiln. 

What are Cones?

Pyrometric cones (usually just called “cones”) are small, pyramid-shaped tools made from ceramic materials. They bend at specific temperature ranges, helping you know how much heat your kiln has absorbed over time.

Think of cones as a more accurate way to measure what’s happening inside the kiln than temperature alone—they account for both heat and time. Digital kilns don't use cones, but instead a thermocouple. Cones are still how we refer to firing temperature. 

Even with a digital kiln, you should always confirm the correct firing temperature for your clay and glazes. This information is typically listed on the clay box or packaging, and it will reference a cone range (for example, Cone 06 or Cone 6).

There is a HUGE difference between Cone 06 and 6. If your clay is designed to be fired to 06 (1860F) and is fired to 6 (2230F) you will melt the clay into a puddle! Confirm that you have entered the correct program before hitting start. 

2. Understanding Bartlett Controllers (Digital Kilns Made Simple)

Many school kilns use Bartlett controllers, which are designed to make firing simple and consistent—even for beginners. These controllers come with pre-programmed firing options, so teachers don’t need to build custom programs from scratch.

• Slow Bisque (S-BC) → Best for student work
• Fast Bisque (F-BC) → For drier, more experienced loads
• Slow Glaze (S-GL) → Safer, more even glaze firing
• Fast Glaze (F-GL) → Faster turnaround for reliable pieces

For classroom use, it’s always safest to start with Slow Bisque when firing student projects. Student pieces often have uneven thickness or hidden moisture, and a slower firing helps prevent cracking or breakage.

S-BC (Slow Bisque)

• A preset program that slowly heats the kiln
• Helps remove moisture safely from clay
• Ideal for beginners and K–12 classrooms

PRHT (Preheat)

• Holds the kiln at 180°F for a set amount of time before firing
• Helps remove any remaining moisture from clay pieces
• Especially useful for thicker or recently finished student work

CONE

• The target firing level (like Cone 06 or Cone 6)
• Always match this to the cone rating listed on your clay or glaze packaging

HOLD

• Keeps the kiln at its top temperature for a set time
• Can improve glaze finish or ensure even firing
• Typically used in glaze firings more than bisque
• Most teachers don't use this function, screen should read 0.00

3. Kiln Safety Basics Every Classroom Should Know

Kilns are incredibly useful tools—but they also reach extremely high temperatures and must be handled with care. Following a few simple safety rules can help prevent accidents and keep your classroom running smoothly.

Always check the controller before opening the lid:

• The display should read “CMPT” (Complete) or “IDLE”
• The temperature inside the kiln should be below 250°F

Opening a kiln too early can expose you to dangerous heat and can also damage your pieces due to sudden temperature changes.

Keep the lid closed:

• Always keep the kiln lid fully closed when not loading or unloading
• Never leave the kiln open and unattended

Maintain Safe Clearance Around the Kiln

Even when the kiln is not in use, the area around it should stay clear:

• Keep at least 18 inches of space on all sides
• Do not store supplies, boxes, or materials on or near the kiln
• Avoid placing anything on top of the kiln lid

This reduces fire risk and ensures proper ventilation.

This helps maintain proper firing conditions and reduces safety risks.

Know Your Emergency Shut-Off

Every teacher using a kiln should know:

• Where the breaker for the kiln is located
• How to shut off power quickly in an emergency

In a situation where something doesn’t seem right, turning off power immediately is the safest first step.