How you load your kiln directly affects how evenly your work fires. A poorly loaded kiln creates cold spots, uneven glaze results, and damaged shelves. A well-loaded kiln uses space efficiently and gives every piece the same heat exposure. This guide covers the principles that apply to any electric kiln load — bisque or glaze.
Kiln Wash Your Shelves
Coat the top surface of every shelf with kiln wash before loading. Kiln wash prevents glaze drips from fusing pieces to the shelf permanently. Apply it with a wide brush in two or three thin coats, letting each dry before the next. Do not coat the underside of shelves — kiln wash on the underside flakes off into the kiln and onto your work.
Wipe glaze off the bottom quarter inch of every piece before loading. Even if you waxed the foot ring, check it. One drip at the base can ruin a shelf.
Shelf and Post Placement
Use three posts per shelf arranged in a triangle — never four. Four posts create a wobble if the floor is uneven; three points always sit flat. Place posts at equal intervals around the shelf, not clustered toward the center.
Set shelf height based on your tallest piece on each level, with just an inch or two of clearance above it. Unnecessarily tall gaps waste space and can affect temperature distribution. Use the shortest posts that safely clear the tallest piece on each shelf.
Keep shelves and pieces at least half an inch from the kiln wall. Elements run along the walls and anything touching them will be overfired or damaged.
Arranging Pieces on Each Shelf
No pieces should touch each other or the kiln wall. Glazed pieces that touch during firing will fuse together permanently. Leave at least a quarter inch of space between pieces — more for runny glazes.
Load the heaviest and tallest pieces on the bottom shelf. Taller pieces in the upper part of the kiln are more vulnerable to the temperature differential between top and bottom. Smaller, lighter pieces can go higher.
Distribute weight evenly across each shelf. A shelf loaded heavily on one side and lightly on the other can crack over time from uneven thermal stress.
Bisque Loading vs Glaze Loading
Bisque firing allows much denser loading than glaze firing because unfired clay pieces can touch and even stack. Bowls can be nested inside each other, cups can be rim to rim. The main limit is structural — pieces must be able to support the weight above them without distorting.
Glaze firing requires spacing between every piece with no exceptions. Glazed surfaces that touch will fuse. The only contact allowed is unglazed foot rings resting on kiln-washed shelves.
Witness Cone Placement
Place a witness cone pack on at least one shelf — ideally both the top and bottom shelf to check temperature distribution across the kiln. Position cone packs where you can see them through the peephole so you can check them during firing without opening the kiln.
Witness cones tell you the actual heat work your pieces experienced — not just the thermocouple temperature. See How to Read Witness Cones and Set Them Up for the full guide.
Loading Checklist
- Shelves coated with kiln wash on the top surface
- Glaze wiped off the bottom quarter inch of every piece
- No pieces touching each other or the kiln wall
- Three posts per shelf in a triangle arrangement
- Shelf height set to just clear the tallest piece on each level
- Heaviest and tallest pieces on the bottom shelf
- Weight distributed evenly across each shelf
- Witness cone pack positioned at peephole level
- Nothing loose that could fall and damage elements
Related Posts
- How to Load a Kiln: Bisque Firing, Tumble Stacking, and Glaze Firing
- Kiln Firing Guide: Bisque, Glaze, Schedules, and Cooling
- How to Read Witness Cones and Set Them Up
- Electric Kiln Maintenance Guide
