The bottom shelf should be 1/2" at least or 1" at most- up off the kiln floor. If there is an element in the floor of the kiln the bottom shelf should be right under the bottom-most side element.
The next shelf should be 8" higher minimum (7" higher if there is an element in the kiln floor). Lower shelves near the bottom make the kiln fire slower.
The next shelf can be closer, with shorter posts, but should never be within 1" of a Thermocouple (Thermocouples or TCs are what is reading the temperature in the kiln- they stick into the kiln a couple of inches).
As you near the top of the kiln, it is better to not have shelves as close to each other again. It is best to have 8 inches between the topmost shelf and the lid (when it is closed).
It is not always possible to have shelves placed like this. The kiln will fire slower with a tighter load, especially if the load is tight in the bottom of the kiln.
Post Placement
Place posts 3 or 4 inches in from the edge of the shelf. Posts on the shelf edges tend to allow the shelves to warp sooner.
Use 3 posts per shelf, this will allow the shelf to sit without a wobble. Use more for heavier loads, especially on the very bottom.
Always put the posts for the next shelf right on top of where the posts are holding up the shelf below. All the posts should be in a line from top to bottom.
Placing posts on their sides under the bottom shelf to distribute the weight is best as long as the bottom shelf's height is not even with or higher than the bottom-most side element.
Half shelves at the same height as each other can share the posts where they meet.
Pottery Loading
Be sure the shelves are kiln-washed if this is a glazed load.
Load pottery on the shelves with tall things in the center of the shelves and shorter things on the edges. This allows the radiant heat to reach the ware in the center of the shelf.
Never load something within 1" of a TC.
Never load something over the edge of the shelf. When you look down on the kiln load from the top (if possible) nothing should be sticking out over the edges of the shelves.
Large flat surfaces should be angled away from the elements and TCs so the reflected radiant heat does not overheat the elements or artificially increase that TC's temperature.
Be sure you close the kiln without breaking anything. Should be a 1/2" space between the tallest piece and the kiln lid when closed.
Greenware pieces to be bisqued can touch each other. Sometimes not all the carbon and impurities can burn out of the clay where clay may be touching it if there is a lot of surface area involved.
Glazed ware cannot touch each other- maybe 1/4" is enough between pieces. (This depends on the expansion amount of your clay body.)
