Loading a kiln is the last step you control before the controller takes over, and it decides how evenly the heat moves through your work. Good habits when loading a kiln protect your pots, your shelves and your elements, and they cost nothing but a little care.
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Quick Answer
When loading a kiln, place shelves level on aligned posts, keep work away from elements and walls, leave air gaps between pieces for a glaze firing, wipe glaze off every foot, and put witness cones where you can see them. Bisque ware can touch, but glazed ware must never touch anything.
Before You Start Loading a Kiln
Preparation takes five minutes and saves a lot of grief when loading a kiln. Inspect the kiln interior, the shelves and the posts every time before loading a kiln, because small cracks and glaze drips are far easier to fix on the bench than inside a hot kiln.
Quick pre-load checklist
- Vacuum dust and loose bits of brick from the floor and walls.
- Check shelves for cracks, warps and old glaze drips.
- Confirm the shelves have a fresh coat of kiln wash if your manual recommends it.
- Make sure the posts are all the same height within each stack.
- Have witness cones and cone supports ready.
- Confirm the correct program is selected on the controller.
Gear that makes it easier
A good set of kiln furniture, such as half shelves, a few sizes of posts and a rolling stand, makes loading a kiln faster and safer for your back. Browse our kiln shelves to see the sizes available.
Bisque vs Glaze Rules for Loading a Kiln
The rules for loading a kiln differ depending on what is in it. The table below compares the two most common loads at a glance.
| Question | Bisque load | Glaze load |
|---|---|---|
| Can pieces touch? | Yes, if stable | No, leave a gap |
| Can pieces be stacked? | Yes, rim to rim or inside each other | Only if the contact points are bare clay |
| Do feet need cleaning? | No | Yes, wipe every foot ring free of glaze |
| Lids | Fire in place | Fire in place with the contact rim bare |
| Kiln wash needed? | Helpful on shelves | Important on shelves |
| Main risk | Trapped moisture, cracks | Stuck pieces, glaze drips |
Setting Up Shelves and Posts
Shelves carry the weight of the whole load when loading a kiln, so the stack must be square and stable. Poor stacking is the most common cause of a tipped shelf, and a tipped shelf can take half the kiln with it.
Align posts, always
Stack posts directly above one another so weight travels straight down to the floor. Use three posts for a round shelf, or four for a rectangular one, and place them near the edges for support without blocking airflow. Give each shelf a gentle push to confirm it does not rock.
Choose the right shelf
Thicker shelves resist warping but hold more heat and slow the cycle, a trade-off we cover in our post on kiln shelf thickness. Match the shelf to the kiln, and never use a shelf that is thin or cracked for heavy loads.
Stay off the floor
Raise the bottom shelf on short posts so it clears the kiln floor. This improves airflow, protects the floor from glaze drips, and keeps the bottom pots from sitting in the coldest part of the kiln.
Spacing Work When Loading a Kiln
Heat needs a path, so spacing is the heart of loading a kiln well. Crowded pots shade one another and heat unevenly, so allow space for air to circulate around each piece. Our guides on kiln shelf spacing and loading a pottery kiln for even firing go deeper into layout patterns.
Distance from the elements
Keep pots at least an inch away from the elements and the kiln wall, or follow the distance in your manual. Pieces too close to an element can overheat on one side and may stick to the brick. Never let pots touch the elements at all.
Space between glazed pieces
A gap of about half an inch (1 to 1.5 centimeters) between glazed pots is a sensible minimum. Leave more room for runny glazes or large pieces, as glaze can bubble and move during the melt.
Clearance at the top
Leave a couple of inches between the top shelf and the lid so heat can circulate and so you can close the lid without catching a pot. Do not stack work against the lid or the lid hinge.
Where to Put Heavy and Thin Work
When loading a kiln with mixed work, remember that large, thick pieces take longer to come up to temperature, while thin pieces heat quickly. Mix them so both are exposed to similar conditions. Put heavy platters and tall vases on the middle shelves, and place smaller cups and bowls near the top and bottom.
Place the tallest work where the posts and shelf spacing allow it, and keep tall thin forms away from the elements. If a piece is very tall, give it its own shelf rather than forcing it into a narrow gap.
Cone Placement and Kiln Furniture
Witness cones show what the kiln actually did. Place at least one cone pack in the cooler and hotter areas, and set them where you can see them through a peephole. Our guide to witness cones for pottery kilns shows how to read them.
If your kiln uses a sitter, set it as the manual describes, and see the details in our article on how a kiln sitter works. Place a cone in the sitter and a witness cone on the shelf nearby so you can compare them afterward.
Step-by-Step Method for Loading a Kiln
If you like a clear order of operations, follow this routine each time. It works for bisque and glaze loads, with the glaze-specific steps noted.
- Let the kiln cool and switch off power at the disconnect.
- Vacuum the floor and walls, and inspect shelves and posts.
- Place the bottom shelf on posts and check that it sits level.
- Load the lowest shelf first, working from the back to the front.
- For glaze firings, wipe all feet, check for runs and confirm gaps between pieces.
- Add the next set of posts directly above the first, then the next shelf.
- Place witness cones where they are visible through a peephole.
- Check clearance to the lid, close it, set the program and record the load in your log.
Working from the bottom up when loading a kiln means you never have to reach over finished shelves, which is when most accidents with pots happen. If you are loading a kiln alone, take your time and keep a clear surface nearby for resting pieces.
Loading Different Shapes and Sizes
Pots are not all alike, and loading a kiln with mixed shapes means thinking about each one. A little extra thought about the shape can prevent warping, sticking and cracking.
Plates and wide platters
Wide flat forms can sag or crack, especially in a glaze firing. Place them on a dedicated shelf or a setter of the same clay, and avoid placing them at the very edge of the shelf. Dry them evenly before the first firing.
Tall vases and bottles
Tall forms need clear vertical space and a stable base. Keep them away from the walls and from the center of the kiln if the manual warns about hot spots. A tall piece on a narrow foot should be wedged with a small support, if needed.
Lidded jars and teapots
Fire lids in place so they warp along with the base and still fit afterward. Wipe glaze off the lid seat and off the matching gallery so the two pieces cannot fuse. Setting a tiny piece of bare clay between them is another tidy habit.
Small items and tiles
Small pieces like tiles, beads and ornaments fill gaps nicely, but keep them well away from the elements. Use tile setters or small stilts and place them on a spare shelf rather than loose among large pots.
How Often to Check and Replace Furniture
Kiln shelves and posts wear out. A shelf that rings dull when tapped, has a hairline crack or is visibly curved should be retired before it fails mid-firing. Posts with chipped ends can make a stack unstable, so replace them as soon as you see damage.
Keep a few spare posts in different heights so you can adjust spacing to suit tall and short work. Having two or three half shelves also gives you freedom to load awkward shapes without leaving big empty spaces. Inspect furniture regularly as part of the kiln upkeep described in the manual.
Common Mistakes When Loading a Kiln
- Glaze on the foot. One glazed foot can weld a pot to the shelf. Wipe the bottom clean with a damp sponge.
- Overloading. Packing the kiln tight gives cold spots and underfired glazes.
- Misaligned posts. A leaning stack can fail halfway through the firing.
- No kiln wash. Without it, glaze drips can fuse permanently to the shelf.
- Pieces too close to the elements. They can overheat or damage the coil, so loading a kiln with a margin is smart.
- Forgetting to check the program. Loading a kiln perfectly and then running the wrong cone is a very costly slip.
Safety When Loading a Kiln
Switch the kiln off at the disconnect and let it cool fully before loading. Wear a dust mask when you vacuum the interior, and gloves when handling rough shelves. Silica dust from old shelves and clay is a health risk, so sweep gently or use a vacuum with a proper filter.
Always follow your kiln manufacturer manual for operation and clearances. Any wiring problem, flickering power or burning smell should go to a licensed electrician, not to a guess. Keep the area around the kiln clear of flammable material.
Frequently Asked Questions About Loading a Kiln
How full should I load a kiln?
Full enough to be efficient, but loose enough for air to move. A crowded kiln fires unevenly, while a nearly empty one wastes power and may heat unevenly in a different way.
Can I stack pots in a glaze firing?
Only when the surfaces that touch are bare clay, such as a fully unglazed rim or foot. Even then, keep the stack stable and leave a little room. When in doubt, keep glazed pieces apart.
Do I need kiln wash on every shelf?
Kiln wash protects shelves from glaze drips and is recommended for most glaze firings. Apply a thin, even coat, let it dry fully, and scrape and recoat when it flakes. Check your shelf maker for advice on your specific shelves.
Is loading a kiln different for gas and electric?
The basics are the same, but gas kilns also need clear paths for flame and flue gases. Follow the manufacturer manual for placement relative to burners, and have a licensed professional handle gas connections.
Final Thoughts
Loading a kiln well is a small, repeatable routine: clean the interior, build square shelf stacks, space the work, clean the feet and set your cones. Do this each time and your firings become more even and your losses drop.
When you need replacement shelves or posts, look through our kiln furniture, or send us a question through the contact page. For technical reference on materials and firing, visit Digitalfire.
