In the past week my friend and studio mate Lavinia and myself finished an epic 9month quest to refurbish our new/old kiln that we scored for free from Bath Spa University where we both got our degrees in ceramics. And yes, it is FINISHED!!!!!!
We scored a Kilns and Furnaces 3phase front loader that used to be at Bath Spa University (we even used it while studying there).
The final stage in being the actual refurbishment. I was encouraged to post about this as there are surely more than a few potters out there daunted by the prospect but too strapped for cash to pay someone to do it for them. I should point out now that we did not do ANYTHING electrical, we did get a professional kiln electrician to do the elements and whatnot.
So that is the before…. what we planned to do is only replace the sides and hearth. Before anyone goes cringing about wasting elements, those were knackered too.
Thanks to the very helpful advice of AG our wonderful local kiln electrician, who spent over an hour of his free time on the phone talking me through what to do. As well as Clive ‘the Kiln Man’ , now retired (mostly) who wound the new elements.
So for our part, I contacted Kilns and furnaces and got a quote for a new set of bricks, we chose this as neither myself nor Lavinia had the time or skill to carve channel bricks etc. K&F were quite reasonable, when you factor in the time and skill factor which we didn’t possess.
top tip: have pliers, rubber mallet, chisel, spray bottle for water, and a vacuum handy. The mortar we used is the same as K&F use to make their kilns. Don’t forget a metal spatula to spread the mortar.
The first thing we did was put the isolator switch to OFF and cable tie it in position, this is very important, you cannot be too careful. Then I started ripping the elements out, they snapped like twigs they were so brittle. Its much easier to rip them out with a pair of pliers rather than bare hands, they are excellent on the pins. Then Lavinia knocked out the left hand side and all of the hearth, she being R-Handed. I took out the right side the following day.
Once all of the rubble was removed, we vacuumed all of the bits out and did a dry run of laying the bricks to make sure they would all fit. Then we started actually laying them. first, we sprayed the sides to hold mortar with water, this was to help prevent the mortar from going off too fast. Halfway up the first side, we got the hang of it.
The bricks provided were for a 1,1,1/2 lay. That meant with each row we changed the position of the 1/2 brick to stagger the lines as best we could. Also we had to make sure the channels would meet up with the holes in the back for the elements. It took me a while to get into the swing of spreading the mortar thinly and evenly, but I got there in the end. There was a little room at the top, but we left it un-mortared (will explain later).
Once we finished that side, we put boards up against both sides of the kiln and wedged them in place, This was to ensure the bricks wouldn’t move while the mortar finished setting. When we got back the next day, they were rock solid.
I left the board we had used to brace new bricks, in place when I started on the right side. The reason for this was to protect the new bricks from my mallet. It doesn’t matter how careful you are, there is always a chance they will get damaged on the backswing. Once the rubble was removed and the area vacuumed again, we did a dry run with the hearth and the first few rows up the side. I was very happy and thought we didn’t have to put all the bricks in (IDIOT!!!). So we laid the side, leaving the hearth empty until we were done. Of course by the time we got to the top row I was getting pretty cocky about it all, and when the last row wouldn’t quite fit, I thought all it would need was a board over the brick and tap the board….. As I mentioned earlier, these bricks are very soft.
After that I refused to put anymore bricks in. But what we did to help them fit is take a little of the top sides of the bricks with a rasp to fit them in. Then we did the boards and brace routine after laying the hearth.
The next day, I started wedging the gaps with kiln fibre. Using a firm, blunt yet fine tool, I stuffed the cracks with bits, building it up till it filled the space. I also filled the gaps along the tops of the sides with fiber until I could stuff no more. Why use kiln fibre instead of the mortar we used on the bricks? The mortar does funny things when used on cracks where the bricks are set particular way, like the doors and roofs. It shrinks away and makes the problem worse. The best way is to wedge it full of kiln fibre which is just as refractory as the bricks and won’t shrink away. We also used fibre along the front of the hearth, the front doorframe bricks got damaged, so we decided not to add mortar as we will replace the damaged ones in the near future.
The roof bricks were ‘repaired’ with mortar, so were the door ones. Both look awful because the cracks are caused by the bricks being pulled apart, when they were stuffed with mortar and the kiln fired, the mortar shrank and pulled away from one side of the crack, degrading the exposed side further. Our problem there is those bricks can’t really be replaced by novices such as us. I think the metal frame of the door is constructed around the bricks, which means any replacement will never be the same. See the first picture and look at the roof, it’s a mess, but it it’s still sound. When I have more time to just sit back and chill, I’ll carefully chip back that mess.
So please please please, do yourself a favour if your kiln needs a little tlc. If you break a bit off, use mortar, but if there’s a crack to fill, stuff it with kiln fibre, your kiln will love you for it. But most cracks don’t need filling
If you were wondering why I have kiln fibre around the door frame, the door got twisted at some point before we got it, I think that’s why there’s a dirty great crack in the bricks. Anyway, the first time I fired Patrick, before the refurb, I went back late at night to check on the firing and found a huge gap along the bottom shining a glowing strip of light on the floor. With shaking hands I stuffed a bit of fibre in there using a longish metal tool, the kiln was over 1100C at that point and about 100C behind schedule. So I sat there one evening after work and framed the door. For that I used the merest smear refractory glue rather than mortar.
The final job was the elements. AG did a sterling job on that, he even fiddled with the thermocouple so it could be placed in the back instead of through the chimney. Here is the shiny new Patrick….
Another thing AG advised me to do, the maintain the new elements, was to do an empty low bisq cycle, then do a bisq for the first filled cycle. When you are only going to get a max of 100-150 (stoneware) glaze firings, proper kiln care is important.
I hope this proves as incentive to anyone else out there daunted by the prospect of refurbishing their kiln. It’s not as hard as it seems, and there is a fantastic network of potters and technicians out there that can guide you through it. But please, don’t do the electrical stuff unless you are a qualified electrician.
I live in Bath, Somerset, UK. So I can’t advise who your local experts are, but I’m sure if you ask a fellow local potter or pottery supplier, they can point you in the right direction.