How you load your kiln directly affects how evenly your work fires. A poorly loaded kiln results in cold spots, glaze defects, broken pieces, and damaged shelves. A well-loaded kiln fires evenly, protects your work, and extends the life of your shelves and elements. Loading a bisque fire and a glaze fire follow different rules — understanding both helps you get the most out of every firing.
Kiln Furniture: What You Need
Kiln shelves — flat shelves that hold your work. Half shelves give more flexibility for odd-sized pieces and allow you to mix heights on the same level.
Kiln posts — support shelves at different heights. Use the shortest posts possible for stability. Three posts per shelf is standard — more posts are needed for larger or heavier shelves.
Kiln stilts — small pointed supports to raise pieces off shelves when glaze covers the base. Only use at low fire — at cone 6 and above stilts can fuse to the piece.
Kiln Wash: Why It Matters
Kiln wash prevents glaze drips from fusing pottery to shelves. Always coat the top surface of shelves — never the bottom. The standard recipe is 50% alumina hydrate and 50% EPK kaolin mixed to a thin cream. Apply two or three thin coats and let each dry before the next. Reapply wherever glaze drips have been scraped off. Check shelves before every glaze firing and touch up bare patches.
Loading a Bisque Fire
Bisque firing is far more flexible than glaze firing because there’s no molten glaze to fuse pieces together. Pieces can touch, be nested inside each other, and be stacked — which means you can fit significantly more work into a bisque firing than a glaze firing.
Standard Stacking
Bowls can be stacked rim-to-rim or nested foot-to-foot. Mugs can be placed upside down with the rim on the shelf and a second mug placed inside. Small pieces can be placed inside larger ones. The only caution is weight — don’t stack so heavily that lower pieces are crushed or deformed. Thin-walled or delicate pieces should not be stacked under heavy ones.
Tumble Stacking
Tumble stacking is a specific bisque loading method where pieces are laid on their sides — literally tumbled — and loaded in a dense, interlocking mass without kiln shelves. Mugs, bowls, and cylinders are placed on their sides and nested against each other in layers from the bottom of the kiln up. The kiln is packed densely with the pieces supporting each other, and firing proceeds normally.
This method dramatically increases the number of pieces you can fit in a bisque firing — sometimes two to three times the volume of a standard shelf-loaded bisque. It’s widely used in production studios and community kilns where bisque efficiency matters. The method works because bisque temperature is low enough that pieces don’t deform from their own weight when lying on their sides, and there’s no glaze to fuse them together.
Tumble Stacking Tips
Start with a base layer of larger, more robust pieces on the kiln floor — bowls face down, mugs on their sides
Fill gaps with smaller pieces — espresso cups inside mugs, small bowls inside larger bowls
Don’t stack handles directly under heavy pieces — handles are the most vulnerable point under weight
Keep the load away from elements and the kiln wall — at least 2cm clearance on all sides
Place a witness cone pack where you can see it through the peephole — even without shelves you need to monitor temperature
Tumble stacking works for greenware bisque only — never for glaze firings
Tip: Porcelain and thin-walled pieces are more vulnerable when tumble stacked. For your best or most delicate work, standard shelf loading with pieces upright is safer.
Loading a Glaze Fire
The Most Important Rule: Glaze-Free Bases
Keep glaze off the bottom 6mm of every piece. Glaze melts and flows downward — any glaze that reaches the kiln shelf fuses the piece permanently. Check every piece before loading by running your finger around the base. Wipe off any glaze with a damp sponge. Wax the foot ring before glazing to make this step unnecessary. See: Wax Resist.
Spacing: Pieces Must Not Touch
Glazed pieces that touch each other in a glaze firing will fuse together permanently. Leave at least a finger-width between every piece on all sides. Check spacing from above and from each side before closing the kiln — a piece that looks clear from the front may be touching another from a different angle.
Loading for Even Firing
Balance the load — distribute weight evenly across each shelf and throughout the kiln height
Do not block airflow — leave a gap between pieces and the kiln wall for heat circulation
Largest pieces at the bottom — thick-walled pieces need more heat and are best near the bottom where elements are strongest in most electric kilns
Minimise shelf height gaps — set shelf height based on your tallest piece plus 2cm clearance. Unnecessary gaps waste space and affect temperature distribution
Runny glazes on lower shelves — if a glaze is known to run, place those pieces on the bottom shelf nearest the kiln floor so any runs drip onto the shelf rather than onto pieces below
Witness Cone Placement
Place a witness cone pack on at least one shelf — ideally top and bottom to check temperature distribution. Position cone packs where you can see them through the peephole. In a tumble-stacked bisque, prop the cone pack against the kiln wall at a height you can see. See: How to Read Witness Cones.
I am a visually impaired ceramic artist. I have been making for around 8 years now. I specialize in functional colorful pottery. Mainly nerikome and other decorative processes.
