How to Improve Heat Distribution in a Ceramic Kiln
1) Load more ware in hot sections of the firing chamber and less ware in cool sections. The greater the density of ware, the more heat required in that section of the firing chamber. By changing the load balance inside the kiln, you can alter the heat distribution by about half a pyrometric cone. For instance, to reduce the heat in a hot section of the kiln, load short pieces of ware that require extra shelves. Load fewer shelves in the cooler sections of the kiln. The shelves are heavy and require extra heat energy.
2) On digital kilns, program a hold of around 15 minutes at the end of the firing. This will help even out the temperature. Firing slower also helps.
3) A down-draft kiln vent that is operating properly helps even out the heat distribution by as much as 1/4 - 1/2 cone. While the kiln is empty and unplugged, turn on the down-draft vent. Hold a lighted match inside the kiln just above a vent hole in the bottom. The flame of the match should be pulled toward the hole. Turn off the vent and load the kiln. Insert the peephole plugs and close the lid. Then turn on the vent and hold a lighted match above and level with a lid vent hole. The flame should be sucked toward the hole. If the lid rises during firing, the down-draft vent will lose efficiency, because it must create negative pressure inside the kiln. Opening the lid or removing peephole plugs reduces the negative pressure.
With best wishes,
Arnold Howard Paragon Industries, L.P. - Better designed kilns 2011 South Town East Blvd. Mesquite, TX 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 firstname.lastname@example.org / www.paragonweb.com