How to Load a Kiln for Bisque and Glaze Firings

Loading a kiln is part Tetris, part safety check. A good load fires evenly and keeps every pot intact. A bad load wastes a firing, damages shelves and sometimes cracks the work of a dozen people.

The rules for bisque and glaze are different, so we will take them one at a time. Always follow your kiln's manual and your studio's rules over general advice.

Before you load

Check that every piece is bone dry for a bisque load. Damp clay can crack or explode. See pottery clay stages.
Check that shelves have fresh kiln wash and no cracks.
Look over your posts for chips and wobble.
Know your cone and firing schedule.

Bisque loading: pots can touch

Bisque ware has no glaze, so it can be stacked more closely than a glaze load.

Pots can touch each other, as long as they sit stably. Rim to rim, foot to foot or nested bowls all work.
Smaller pieces go inside larger ones to use space.
Keep weight low and balanced. Heavy pieces go on lower shelves.
Leave space for heat to move. Don't pack the kiln solid.
Lids can be fired on their jars to keep them flat and matched.

Our lesson on the rules of bisque loading goes deeper.

Glaze loading: nothing touches

Glaze melts into a liquid and will fuse any surfaces that touch.

Wipe the foot clean of glaze before loading.
Leave clearance between pots. A common rule is about a finger width or more (roughly 1 to 2 cm), but check your studio's rule.
Don't let glazed surfaces touch shelves, other pots or kiln walls.
Keep pots away from elements. Stay well back from the walls and any heating element as your kiln manual specifies.
Be careful with tall pieces, which can sit too close to the next shelf.

See why clearance is everything.

Placing shelves and posts

Place posts in a stable pattern, usually three or four per shelf, with the shelf level.
Line up each tier so weight passes straight down through posts, not onto a shelf's edge.
Match post height to your tallest pot plus clearance.
Don't block peepholes, thermocouples or vents.
Test for wobble by gently pressing the shelf before the next layer.

Practice with a practice shelf with posts.

Plan on paper first

Sketch the kiln as stacked rings and assign each pot a position. It takes five minutes and prevents rearranging heavy shelves. Our exercise on planning a bisque load on paper shows how.

Common mistakes

Overloading a shelf so it bends or the load shifts.
Putting wet or damp pieces in a bisque.
Letting a glazed foot touch the shelf.
Ignoring cone differences. Don't mix clays or glazes with very different cones in one load.
Not recording the load. Write down who put in what.

Use a loading record

A written list of what went in, where, and which cones were used, helps trace a problem later. Many studios keep a clipboard. A shared digital record is easier to search. Claybook can tag every piece in a load with the firing and update them all at once after the kiln opens.

After the firing, learn how to read the results with the cone chart and check for runs with why did my glaze run.