Kiln rebuilding
Feb. 23rd, 2015 07:06 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
offcntrWe last rebuilt the car kiln at Club Mud in 2013, and though the walls and arch are holding up well, the door has been a problem. The hot and cold sides of the brick had separated, bricks were cracking, bulging inward and interfering with the flame path. Gaps also opened up, allowing air leaks which foster patches of oxidation in the clay and glazes. We nursed it through critical holiday firings, then set aside time to rebuild the door in the new year.
I budgeted a couple of weeks for the project, but in fact, it took two working days with two potters, Jon King and myself. We recycled some brick from the old door, used up most of the club's back stock, and wound up ordering four boxes of K23 soft brick, of which we used two.
The old door. You can see some cracks and sooty air leaks, but the worst damage is only visible edge on, where the brick on the inside, hot surface separated and bulged away from the outside.
The first few rows. The heat damage seemed worst on the bottom, so we incorporated some rescued K26 brick (rated for 2600° F.) at this level. At first, we stacked recycled whole brick from the old door on a ware board on the kiln floor, but couldn't shut the door, so we moved them onto the car, then couldn't reach them when the door got too high. Seems like everything got moved at least three times…
Making progress. We're trying to be more conscious of staggering seams between front and back, and tying the two layers together with brick every third row instead of fourth.
Cutting soft brick to fit is fussy, but not terribly difficult--it's very friable. Light streaks on the wall show where we've used cement block to rasp down bricks that don't quite fit.
At the end of Tuesday, we've torn down the old door, and rebuilt to a couple rows beneath the top peep. We've also completely run out of brick, and need to wait until Jon goes up to Portland Thursday to pick up a clay order. Back to work on Friday.
Reaching a tricky section: the inner layer of brick goes in under the arch. We've saved a couple of curved bricks from the old door, but much of what we put in will be sculpted to fit with saw and surform.
Almost done. The steel beam across the top is up and the tie rods connecting it to the bottom are tight. All that's left is to cement thin splints of brick across the front of the steel to protect it from flame leaks during body reduction.
Finished! And a celebratory picture… Maybe Jon could send me one he took…
Next firing is Jon's, early in March. I'm scheduled for the 29th, so it's back into the studio for me.
I budgeted a couple of weeks for the project, but in fact, it took two working days with two potters, Jon King and myself. We recycled some brick from the old door, used up most of the club's back stock, and wound up ordering four boxes of K23 soft brick, of which we used two.
The old door. You can see some cracks and sooty air leaks, but the worst damage is only visible edge on, where the brick on the inside, hot surface separated and bulged away from the outside.
The first few rows. The heat damage seemed worst on the bottom, so we incorporated some rescued K26 brick (rated for 2600° F.) at this level. At first, we stacked recycled whole brick from the old door on a ware board on the kiln floor, but couldn't shut the door, so we moved them onto the car, then couldn't reach them when the door got too high. Seems like everything got moved at least three times…
Making progress. We're trying to be more conscious of staggering seams between front and back, and tying the two layers together with brick every third row instead of fourth.
Cutting soft brick to fit is fussy, but not terribly difficult--it's very friable. Light streaks on the wall show where we've used cement block to rasp down bricks that don't quite fit.
At the end of Tuesday, we've torn down the old door, and rebuilt to a couple rows beneath the top peep. We've also completely run out of brick, and need to wait until Jon goes up to Portland Thursday to pick up a clay order. Back to work on Friday.
Reaching a tricky section: the inner layer of brick goes in under the arch. We've saved a couple of curved bricks from the old door, but much of what we put in will be sculpted to fit with saw and surform.
Almost done. The steel beam across the top is up and the tie rods connecting it to the bottom are tight. All that's left is to cement thin splints of brick across the front of the steel to protect it from flame leaks during body reduction.
Finished! And a celebratory picture… Maybe Jon could send me one he took…
Next firing is Jon's, early in March. I'm scheduled for the 29th, so it's back into the studio for me.