Packing a kiln is like a very tedious game of jenga/tetrus. The shelves have to be placed in the center to assure even temperature flow and the kiln posts have to be placed properly to provide the most support. Pots have to be organized according to height to maximize the use of the kiln space though they can't touch one another. I've gotten very good and eyeing out how many pots will fit in the kiln and packing it full for maximum efficiency.
The large pyrometric cones called witness cones are colored to help distinguish them from one another. During the firing process they become calcified and loose their color. They are set in a piece of clay riddled with holes to allow the water and any air bubbles in the clay to escape. Without the holes, the water in the clay would boil and the air would expand causing the clay to explode and leaving little shards of raw clay all over the surrounding pots.
I use an electric kiln with a mechanical automatic shut off mechanism called a Kiln Sitter. It is controlled by a small lever inside the kiln that rests on a small cone that melts at a specific temperature. When the cone melts, the lever drops down, releasing the latch on the outside and breaking the flow of electricity turning the kiln off.
The kiln stays on low for an hour and then an hour on medium and 9 hours on high. Once its on high all we can do is wait and cross our fingers and make sure that its off after 9 hours. It cools for at least 8 hours before we can open it. The waiting is SO hard but I'm learning to keep myself busy.