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Kilns

Posted: Wed Feb 19, 2014 1:33 pm
by BobbieMatus
I have a 28 inch JenKen which is now completely rusted out, husband says it needs to be rewired and he hates the quality of it. I fire everyday, kiln is about 12 years old . I replaced the lid two years ago.I burn out elements a lot and my husband replaces them cursing as he does it. My question is should I keep repairing or buy a new one. Is there a better made kiln out there

Re: Kilns

Posted: Wed Feb 19, 2014 4:00 pm
by Kevin Midgley
Don't buy a kiln with nichrome elements. Nichrome is a cheaper wire than Kanthal A1
Kanthal A1 is the way to go so long as you do not fire with combustibles in the kiln. Burning anything will damage the Kanthal element's protective coating that develops .
That means using kiln wash instead of the alternatives.
I can't recall ever having to replace elements in 35 years of firing glass from breakages inside the kiln.
They can go at the pigtails where you connect to the power supplies if you use cheap connectors not tightened correctly.
Elements also have to be stretched correctly prior to installation or they will burn out.

Re: Kilns

Posted: Wed Feb 19, 2014 4:53 pm
by BobbieMatus
kiln wash is not an option for me as I fire everyday. didn't know about stretching the elements

Re: Kilns

Posted: Wed Feb 19, 2014 5:03 pm
by Brock
kiln wash is not an option for me as I fire everyday.

So? I did it for decades . . .

Re: Kilns

Posted: Wed Feb 19, 2014 6:57 pm
by Morganica
So let's talk about why you're burning out elements so often, and why daily firing means you can't use kilnwash?

I've had my Skutt for more than 12 years and I'm still on the original elements. It's not rusted out, although it's pretty beaten up because I've been casting in that kiln for years. I also use kilnwash.

So...I'm wondering what it is you're doing that's different?

Re: Kilns

Posted: Wed Feb 19, 2014 8:08 pm
by Jeanne
Just wondering what the environment is where you keep your kiln?

Re: Kilns

Posted: Wed Feb 19, 2014 10:09 pm
by Lynn Perry
I have a 24" JenKen that I purchased in 1997 and it has been used extensively for the last 10 years. I do not have any rust on the metal, and I have only replaced the heating elements once about 5 years ago. The relays failed about the same time, so those were also replaced. My kiln has lived in an unheated basement for 17 years. I have also used only ceramic fiber or a paper so the kiln has experienced plenty of combustibles and glue, too. I wonder if the metal they used for your kiln was from a bad batch.

Re: Kilns

Posted: Wed Feb 19, 2014 10:37 pm
by dee
i doubt it is the kiln wash. i have a jenken that i have fired in daily with kiln wash for 11 yrs, my mentor had 3 jen kens she fired in with kiln wash daily for many years and they never had this level of trouble. i live in the southeast, land of the humid with my kilns in what would be a garage. there is something going on that is not related to kiln wash here. i've yet to have to replace my elements...

Re: Kilns

Posted: Thu Feb 20, 2014 12:11 am
by Bert Weiss
Kevin, Nichrome is far more expensive than Kanthal A-1. I have always used nichrome in the kilns I have built, but I reluctantly will switch to Kanthal A-1, due to cost. I really like nichrome elements, for one thing, they burn out around 2000 or 2100, so a runaway will not get so dangerously hot. I use a heavy gauge wire strung straight, not coiled.

I don't really know why Bobbie has her problems with element burnout.

Re: Kilns

Posted: Thu Feb 20, 2014 3:07 am
by Mark Kemp
Kevin, can you explain what you mean about elements needing to be stretched correctly?

My Jen-Ken is 10 years old, or maybe more -- can't remember -- my brain is old. But I've replaced the elements quite a few times, and I'm not burning weird stuff much. They were going at 6 months for awhile, then I was finally told they had been sending me the wrong element -- I had the impression they were the wrong length. But when I called this last time, he said it must have been something else, and would send me a heavier one. But I've had to stretch every one to make them fit -- so I wonder if that is harming them. This last one did last several years, and may have just burned out because the drooping got so bad.

Re: Kilns

Posted: Thu Feb 20, 2014 10:42 am
by BobbieMatus
I think it rusted out because I was venting through the peep hole. Mike at JenKen told me to crack the top open and vent to 1000 degrees. How are all of you venting.

Re: Kilns

Posted: Thu Feb 20, 2014 10:52 am
by Bert Weiss
elements are engineered according to a calculation called watt loading, or the number of watts per square inch of element surface. Elements on a rod, sitting in open air, can handle the highest watt loads. As you embed elements in a groove in insulating firebrick, the watt load must go down. Totally embedding them in fiberboard requires the lowest watt load. As a wire gets shorter, it draws more wattage. Increasing the wire gauge will lower the watt load. Watts = Amps x Volts. Surface area is circumference x length.

So, if you are having trouble with burnouts, one solution is to get an element with the same wattage in a heavier gauge. However there are limits to the stretched length of an element. Elements have a recommended range of lengths where they work well.

To get even heat from a coiled element, you must stretch it evenly.

I recommend Duralite in CT to provide after market elements. They can engineer anything different, and they know all the kiln manufacturer specs.

Bobbie, you should be able to do routine things like kilnwash, vent, and peep. Crashing is harsh though...

Re: Kilns

Posted: Thu Feb 20, 2014 11:01 am
by Brock
Crashing a kiln is hard on bricks, not elements . . .

Re: Kilns

Posted: Thu Feb 20, 2014 11:10 am
by Jeanne
BobbieMatus wrote:I think it rusted out because I was venting through the peep hole. Mike at JenKen told me to crack the top open and vent to 1000 degrees. How are all of you venting.

It is recommended to keep the lid propped a little to 1000F if you are using glue, thinfire or other additives. How close are you to the ocean?

Re: Kilns

Posted: Thu Feb 20, 2014 1:33 pm
by BobbieMatus
I use thin fire so I'm keeping the lid open just a little to 1000 degrees should I keep the peep hole open as well or close it? Is this crashing?? How does everyone vent their kiln. I tried doing the kiln wash but doing shows alsmost every week-end and constantly working made thin fire a must for me. Really hated the kiln washing .I'm 8 miles from the ocean. Kiln is in the garage.

Re: Kilns

Posted: Thu Feb 20, 2014 2:43 pm
by Jeanne
I don't keep my peep hole open - just the top. I would think the humidity in Florida, your proximity to the coast, plus your kiln in the garage (not climate controlled) might play a factor in the rusting.

I don't crash cool my kiln anymore. Too many here have mentioned that it's tough on the bricks (I have 2 brick kilns). I just program my firings for either a slightly lower temp and/or a shorter hold to account for the retained heat.

Re: Kilns

Posted: Thu Feb 20, 2014 6:20 pm
by Morganica
Brock wrote:Crashing a kiln is hard on bricks, not elements . . .

Really not elements? I'd heard it was difficult on both, and would wear the elements out faster. Now trying to figure out where I've heard that.

Re: Kilns

Posted: Thu Feb 20, 2014 6:24 pm
by Morganica
BobbieMatus wrote:I use thin fire so I'm keeping the lid open just a little to 1000 degrees should I keep the peep hole open as well or close it? Is this crashing?? How does everyone vent their kiln. I tried doing the kiln wash but doing shows alsmost every week-end and constantly working made thin fire a must for me. Really hated the kiln washing .I'm 8 miles from the ocean. Kiln is in the garage.

No, that's not crashing, and it's correct. If you're in Florida that close to the ocean, this may be just be the salty air/humidity thing (does your car have the same rust problem? mine did when I was that close to the sea)

I vent the same way--I crack the lid an inch or too. And the salt air may have something to do with the kilnwash durability, I don't know...but I generally get months and months out of a kilnwashed shelf, even with constant firing. What kilnwash are you using?

BTW, I very much like your flapper series. Reminds me of Wendy Saxon Brown, one of my favorites.

Re: Kilns

Posted: Thu Feb 20, 2014 6:50 pm
by Brock
Morganica wrote:
Brock wrote:Crashing a kiln is hard on bricks, not elements . . .

Really not elements? I'd heard it was difficult on both, and would wear the elements out faster. Now trying to figure out where I've heard that.


I'd be interested too. I just used common sense. The element is firing at it's temperature, opening the door for a short while will make the interior temperature drop. Why would that affect the element? It's far hotter than the ambient temperature of the kiln, closed or open.

Re: Kilns

Posted: Thu Feb 20, 2014 10:20 pm
by Brad Walker
Brock wrote:
Morganica wrote:
Brock wrote:Crashing a kiln is hard on bricks, not elements . . .

Really not elements? I'd heard it was difficult on both, and would wear the elements out faster. Now trying to figure out where I've heard that.


I'd be interested too. I just used common sense. The element is firing at it's temperature, opening the door for a short while will make the interior temperature drop. Why would that affect the element? It's far hotter than the ambient temperature of the kiln, closed or open.


I had always believed that ventilation -- even leaving the vent hole open -- increases the life of the elements by getting rid of potential contaminants. If that's so, then I suppose that opening the kiln would help, too.