Tennessee Tech University - Appalachian Center for Crafts - Clay Studio 

Vince Pitelka, 2006

General Hoggama Firing Schedule

First Day
Finish loading in afternoon or early evening.  Brick up door to leave stoke hole approximately 12" wide by 15" high in center of door.  Build temporary “fireplace” in front of kiln so that it exhausts into upper air ports.  Close off other air ports and stoke hole.  Open kiln dampers halfway.  Build and maintain small fire in front fireplace, burning odd small and medium scraps that are laying around.  Watch pyrometer, hold kiln temperature around 250F for four hours, and then allow to climb 100 degrees per hour.  Do not stir the coal bed at all at any point during the firing except very gently when necessary to raise uncombusted material from within the coal bed.  The fire alone creates plenty of turbulence to promote a reasonable amount of fly ash.    

Second Day
12:00 Midnight - Move fire inside firebox.  Stoke a mix of small and medium hardwood and pine every 15 to 20 minutes, increasing temperature 100 to 150 degrees per hour. 

8:00 AM - Stoke mix of medium and large hardwood and pine every 15 minutes. 

12:00 Noon - Should be around 1400F.  Stoke hardwood and pine every 10 to 15 minutes. 

3:00 PM - Should reach cone 010.  Stoke large hardwood every 10 to 15 minutes.  When cone 010 is down in front, close dampers enough to begin observing flame at rear crown port, and begin breathing cycle stoking, allowing flame to recede back into crown port for at least five minutes before stoking.

7:00 PM (Approximately) -   When the back is good and red, start backstoking a few sticks alternating with each frontstoke of a mix of hardwood and pine.  Through the evening, watch temperature and do not allow kiln to climb more than 150 to 200 degrees per hour.  As evening progresses, try to have cone 8 softening around midnight .

10:00 PM - Continue to alternate backstoking a few sticks to each frontstoke.  Do not allow a coal bed to build up in back.  It serves no purpose, because it gets no oxygen from beneath, and it damages adjacent pots.

Third Day
12:00 Midnight - Cone 8 should be starting to bend in front.  Slow down frontstoking (main firebox), and proceed very gradually.  At this point it is critical that kiln not climb more than 15 to 20 degrees per hour.  Backstoke a few sticks twice to each frontstoke.  Adjust the amount to assure that no coal bed builds up in back.  Through the night and morning, stoke cautiously in order to prevent front of kiln from climbing excessively. 

6:00 AM - Cone 8 should be down, cone 9 just softening.  Watch cones and pyrometer carefully, and do not let front of kiln go beyond cone 9 softening.   Continue backstoking twice to each front stoke to raise temperature in back. Adjust backstoking as needed for desired temperature.  Do not let a coal bed build up in back. 

12:00 Noon - Ideally, cone 9 should be bending front and back.  Stoke mix of hardwood and pine every 10 to 15 minutes. Watch rear cones carefully, and regulate frequency of backstoking to keep back even with front if possible.

8:00 PM - Cone 9 should be down in front with cone 10 bending, cone 8 down in back.  Regulate frontstoking to carefully to maintain temperature with very slow climb, and don’t let the temperature drop.  Adjust backstoking to keep back climbing with front. 

Fourth Day
12:00 Midnight - Cone 10 bending or down in front, cone 9 down in back.   Try to hold the kiln at this stage through the night, without further cone movement, but without heat loss.  Continue to stoke mix of hardwood and pine every 8 to 15 minutes, backstoke as needed.  Be sure to avoid excessive stirring or agitation of coal bed.

8:00 AM - cone 10 down, cone 11 soft.  Backstoke as needed to get cone 10 bending in back.  Try to hold this through the day with no significant temperature increase or loss. 

4:00 PM - Assuming firing is on schedule to this point, and back is at least cone 10 bending or down, prepare for the final stretch of frontstoking (no more backstoking).  Stoke every five or six minutes with eight or ten pieces of mixed pine and hardwood inserted gently to minimize fly ash.  Try to control climb so that over several hours cone 12 starts to bend.  When cone 12 is bending, open the mouse holes to feed air into the coals, continue stoking lightly as you seal up the other air ports, and feed smaller pieces of wood in as you brick up the stoke hole.  Once all other air ports and the stoke hole are sealed, close the mouse holes with bricks and cover the openings with dirt.  Seal the crown ports and backstoking hole, and cap the stack with kiln shelves. Go have a beverage.