Before loading the ceramic pottery kiln, make certain that the kiln is cold and turned off. Then, place a two- or three- inch kiln support beneath the kiln’s bottom shelf. There is no point in firing on the kiln’s floor, since the bottom is always cooler than the upper part of the kiln. Also, you would be running a risk of having the glazes run onto the floor in case of over firing and thereby damaging the kiln. Be sure that the shelves have been treated with kiln shelf wash on the upper surfaces. After putting in the first shelf, if multiple shelves will be needed then arrange the ware so that the taller pieces are fired on the first shelf and shorter pieces are fired on upper shelves. This arrangement helps to distribute the heat since heat rises, so opening up space in the lower portion of the kiln allows for better air circulation and even heat distribution throughout the chamber.
If you are firing Bisque (first firing) then it is okay to load Amaco kilns tightly; you can even place pieces on top of one another. Remember to leave enough room to put the cone in, which should be able to bend without touching any ware. On the other hand, when firing glazed pottery enough room must be left between each piece since they will stick together if they touch ceramic pottery. This means allowing a space of one to two inches between pieces themselves and the kiln wall. If the underside or foot of the ware is unglazed, then it can be placed directly on shelves which have been treated with kiln shelf wash. But if the ware is glazed on the bottom, it must be placed on stilts. Be sure that the ware is well-balanced on the stilts so that it doesn’t tumble off. Once the ware is glaze-fired, the stilts’ marks can be ground off with either a carborundum stone or with an electric grinder. Use goggles when grinding, and remember that the broken-off stilts are quite sharp.
Most kilns have an electronic control or a kiln sitter. Either of these are adequate for indicating temperature, and they are practical since they shut the kiln off automatically when the firing process is completed. The most accurate reading, however, is obtained from using guide cones – whether self-supporting or regular. It is a good idea to put a cone on every shelf of the kiln, particularly when you begin using a kiln. This will indicate temperature differences from the top of the kiln chamber to the bottom. Put the witness cone in front of the middle peephole, in front of the Amaco ceramics. As the temperature in the kiln rises, the witness cone bends. Correct firing causes the cone to bend to a ninety-degree angle. Junior bars or cones are part of the kiln sitter, and they automatically shut off the kiln as they heat and bend.