How do i kiln fire clay projects?
I need to know the basic steps of how to kiln fire clay projects. Namely, times and temperatures (cones) and the difference between firing grog clay and grogless clay. also any tips on how to pack a kiln would be appreciated.
- Anonymous1 decade agoFavorite Answer
2 different firings:
For Bisk Ware, most clays like cone 6 ... will fully fuse the clay and the pieces will then be ready for glazing.
Make sure all greenware is fully dry, has NO air pockets in clay when throwing or casting (air pockets will cause the greenware to literally explode in the kiln, wiping out all that is around it.
Greenware can be stacked on top of each other, touch each other, etc....pack the kiln as full as possible, but not too much weight on any one item, for it could break due to weight..use kiln shelves after that weight has been met in stacking. Bring the kiln up very slowly at first, hour by hour for about 4 hours to drive out any water in the greenware. PLease note..greenware must be as dry as it can get in the room you are working in BEFORE it goes into a kiln. Leatherware is NOT greenware! Leatherware is still workable for carving, etc. You cannot carve greenware, and greenware is very delicate until it is fired.
Glazing: Make sure that the glazes you use on the fired "bisk ware" all fuse/melt at about the same temperature. Usually, cone 05 - 06 are used for glazes. Again, bring up the kiln slowly at first, hour by hour for about 4 hours, then set timer (cone type turn off) and the kiln will do the rest. DO NOT allow glazed products to touch eachother, do not allow glazing to get on the bottom of the bisk ware...keep about 1/4" off bottom, or you will fuse the pottery to your kiln shelves...very expensive lesson! All the above assumes you are doing oxidation firing. Reduction firing requires other considerations, and usually these kilns are fired by gas. Oxidation kilns are fired by either gas or electric. When bring up the temperatures, leave plugs out of kiln to allow release of any moisture. Once everything in the kiln is very hot and ready to go to kiln cone temps, place all plugs in kiln, remove ONLY to see cones. IF you have a kiln sitter, it will turn off automatically when the cone goes down. If you do not, then use a 3 cone system, one cone number on either side of the desired cone temp...when the lower goes down, you are near temp. When the center goes down, you are at temp, IF the higher goes down, you have left the kiln on too long.
Porceling firings are at cone 10....very high temp. Good luck