What Holds Your Pots Up
The inside of a kiln is not just an empty oven. It is a precisely arranged structure of shelves and posts (collectively called kiln furniture) that holds your pots at different levels and allows heat to circulate evenly around every piece.
Kiln Shelves
Kiln shelves are flat, refractory (heat-resistant) slabs that pots sit on. They are typically made from cordierite or mullite, materials that can handle repeated thermal cycling without cracking.
- Half shelves are useful for flexibility: you can arrange them at different heights in the same level.
- Full shelves are more efficient for large loads.
- Shelves conduct and store heat, contributing to an even temperature inside the kiln.
Kiln Posts
Kiln posts are columns (cylinders or squares of refractory material) that support the shelves at different heights. They come in various heights (typically 1cm to 15cm).
- You always use three posts per shelf (never four). Three points define a plane; four can rock and make the shelf unstable.
- Posts are placed in a triangular arrangement, usually near the outside edge of the shelf.
Why Furniture Matters
Kiln furniture directly affects the firing. Poorly arranged shelves restrict heat flow, creating hot and cold zones. Over-loaded shelves can bow and crack. Understanding your furniture is essential for consistent, even firings.
Furniture Setup Checklist
Before loading pots:
- Verify shelves are level and stable
- Use three-post support pattern per shelf
- Keep element-side clearance for airflow
Stable furniture is the foundation of a safe firing.
Go Deeper
Kiln shelves and posts are made from the same refractory materials used to build the kiln itself, engineered to survive thousands of degrees of thermal cycling. Potters use pyrometric cones placed among the furniture to verify that heat is reaching every shelf level evenly.
