Kiln Loading Checklist: 12 Steps Before You Close the Lid
You wedge the clay carefully, throw with intention, glaze the pot evenly — and then undo all of it with one loose kiln post. Loading is where good work quietly goes wrong: a shelf that tilts, a cone you cannot see through the peephole, a glaze drip that fuses a teapot to the tile beneath it. None of it is mysterious. It is a routine problem with a routine answer.
Once you know the routine, it takes ten or fifteen minutes. Work in order: kiln first, then furniture, then cones, then ware. The goal is not perfection; the goal is predictability. A kiln that is clean, level, and easy to read will forgive a lot of other small sins.
Look at the kiln before a single shelf goes in. It should be cool and disconnected from power. Shine a light along the side walls and check the elements — look for sagging coils, corrosion, or gaps in the brick grooves. An element that has popped out or is touching a shelf can arc, short, or leave a cold spot. Run a gloved finger along the grooves only after the power is off, and use a mirror to see the back wall. If you find a loose element, do not load the kiln until it is repaired.
Check the thermocouple, kiln sitter, or controller next. A bent thermocouple can read low, causing an overfire. A kiln sitter that sticks can fail to shut off. A digital controller with a frayed wire can reset mid-firing. Look at the lid and lid seal: a warped lid or missing brick can let heat escape and make the top shelf fire unevenly. Vacuum the floor and walls. Dust from previous firings, glaze chips, and bits of kiln wash can fuse to shelves or ware. Finally, confirm the peephole is clear and the plug is nearby. You will need to look in without opening the lid.
Kiln furniture is not a pile of random props. It is a structure. Start with clean, flat shelves. Reject any shelf that is cracked, deeply warped, or coated with lumps of old kiln wash. A shelf that rocks on the floor will rock all the way up. Apply a fresh, thin coat of kiln wash if the old surface is bare or flaking. Let it dry before loading.
Use posts of matching height. Mixing a 4-inch post with a 3-inch post is a recipe for a tilted shelf and a glaze pool. For round shelves, three posts can work, but four is more stable, especially for heavy loads. Place posts directly over the supports below so the weight travels straight down to the kiln floor. If you stagger them, the shelf may sag. Check that no post or shelf touches an element. In most kilns, you want at least a half-inch of clearance, but follow your manufacturer's instructions. A shelf that touches an element can crack, short the kiln, or leave a cold line across the load.
Level each shelf as you go. A small spirit level is enough. If the shelf is not level, glaze will run downhill. A mug that looks fine on the wheel can arrive with a thick foot ring and a bare lip. A plate can warp. A teapot can fuse to its lid. Leveling takes seconds now and saves hours later.
Cones are your proof. The controller may say cone 6, but the witness cone tells you what the ware actually experienced. Place self-supporting cones on each shelf, or use a cone pack with guide, target, and guard cones. At minimum, put one cone where you can see it through the peephole. If the kiln fires unevenly, place cones front, back, top, and bottom to map the heat. A top shelf might bend cone 6 while the bottom shelf only reaches cone 5. That is useful information, not a failure.
Keep cones away from elements, ware, and direct drafts. Do not bury them behind a tall vase. Do not let a shelf block the peephole. If you use a kiln sitter, set the correct bar and cone for the firing. If you use a digital controller, double-check the program, ramp, and hold. Then look through the peephole one last time. If you cannot see the cone, move it. A firing you cannot read is a firing you cannot repeat.
If you cannot see the cone, you cannot trust the firing.
Heat needs to move. Leave space between pots — usually a quarter-inch to a half-inch for glazed ware, more for tall pieces. Do not let glazed surfaces touch each other or the shelf. Use stilts, wadding, or a thin cookie of clay under risky pieces. A cookie catches drips and can save a shelf. A stilt lifts a glazed foot, but it must be stable and clear of elements.
Put heavier pieces low and lighter pieces high. Keep tall work away from elements and the thermocouple. If you are firing plates, consider firing them on edge in a plate setter or on a bed of sand, rather than flat, to prevent warping. If you are firing bowls, nest them only if you know the glazes will not run together. For lids, leave them slightly ajar or use wadding to keep them from fusing. For teapots, separate the lid from the body if there is any chance of glaze bridging. For mugs, keep handles from touching the shelf or other pots. A handle that sags onto a shelf can weld the mug in place.
Glaze drips are the most common kiln-loading disaster. Leave a clean margin at the foot of each pot. Wax the foot ring if needed. Wipe away any glaze that has crept onto the shelf. If a glaze is runny, place the piece on a cookie. If you are unsure, test a tile first. The kiln is not the place to discover that your new glaze flows like honey.
Photo: 9nails / Pixabay
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