Monday, March 30, 2015

Kiln Repair

Well, it finally happened. I finally had to replace the muffle in my SC-2 kiln. The muffle is the white ceramic fiber box that lines the inside of the blue metal casing. The muffle doesn't always need replacement, I know artists who have had their kiln for years and never had to fix anything but the occasional thermocouple. But, this kiln was showing the evidence of wear and tear for a long while. The time had come.

Fiber muffle kiln with crack
The kiln had endured a long car trip from the west coast to the east with a forgotten ceramic post rattling around inside. That's what caused the original ding in the wall. Numerous carbon firings later, the fiber really began to degrade, cracks got larger, and eventually my metal clay pieces were coming out either under-fired or over-fired. The photo to the left shows how it looked in 2012. I contacted the manufacturer and they thought that as long as the elements weren't exposed, it didn't need to be repaired and that the kiln should operate well. It did for another couple of years (although, I finally had to lower the top temperature that I fired to 1640ºF instead of 1650ºF for my fine silver work). Then, it didn't work as well at all.

Crack after being ignored for two years
I decided to order another muffle and googled 'kiln repair' in my city to find a repairman. There is a material called Pyrolite that I might have chosen to use to patch the crack, but I decided to go for the more expensive option. Hmmf! I don't remember ever seeing exposed elements, but this is what the crack looked like by the time the repairman had removed the muffle from the kiln (the black stuff is just carbon dust).

It took about 1.5 hours for the professional to complete the transformation. Even though there is a fabulous video tutorial available, I don't think I would have had either the tools or the nerve to manage it on my own. The muffle itself was about $300.00 plus shipping, and the labor added to that total. Pricey, but less than the cost of a new kiln. Maybe I should have looked into the Pyrolite patching compound first.

Naked muffle
The muffle was relatively light and small, easy to handle even in the shipping carton. The repairman had a tall toolbox of screwdrivers, a vacuum, and other tools of the trade. The repair was completed on my studio's table top. He even came to me! No muss, no fuss. Now I have a pristine kiln that I can't wait to mess up!

Here are my tips if you ever have to fool with your own kiln.
1. Make sure to note exactly what's going on. If there are error messages on the digital readout, write them down.
2. Visit the company's website or call them to see if they can offer some tips.
3. If necessary, ask for an employee's email address so you can keep a record of your 'conversation'.
4. Take pictures to help the employee understand the nature of the problem.
5. Proceed in the way that makes you most comfortable. It's not 'better' to do it yourself if you'd rather not.
6. Replacing the thermocouple is super easy! Don't be afraid of that. I've done it myself.
7. Loosening or tightening the door closure/knob is also easy. As is loosening the door hinges for easier/smoother access for enameling.

Beautiful new muffle installed in my smoke 'tattooed' kiln!

Posted by Lora Hart
Artistic Advisor

1 comment:

Janet Alexander said...

Thanks Lora! I didn't know about Pyrolite! I'm purchasing a tube before my kiln becomes worse! Cost is $28 + shipping.