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kiln element failure diagnosis

updated fri 2 dec 11


jonathan byler on thu 1 dec 11

I did a little more poking about in the kiln with the burned up
elements today while cleaning up in our kiln room. It appears that
all of the element staples have corroded away, and that the spots
where they were are now discolored on the kiln's elements. I have
been able to rescue a few little scraps of the staples as evidence,
but they are extremely brittle and crumble when I try to extract
them. I think mismatched alloys between the elements and the staples
is probably the source of the failures. The elements were coated with
ITC 100HT when I coated the inside of the kiln and replaced the
elements the last time. I am guessing that this is why they only just
started to fail: the ITC was keeping the elements and the staples
from touching much if at all, so it too longer than normal for the
mismatched elements and staples to fail. Now that the ITC has been
slowly flaking off of the elements, it is allowing contact with the
staples and causing the burned out sections

I will be contacting my supplier about this, hopefully they can remedy
the problem by sending a new set of elements with the correct
staples! in the mean time, I will be trying to get what remains of
the staples out of the element grooves and hope for the best. end of
semester crunch time here...


On Nov 3, 2011, at 2:02 PM, Arnold Howard wrote:

> Hi Jon,
> I've been thinking about your elements. Have the elements burned out
> in the same location as the previous elements?
> How deep has the discoloration penetrated the firebrick grooves?
> Maybe you could dig out the discoloration with a screwdriver.
> Sincerely,
> Arnold Howard
> Paragon Industries, L.P., Mesquite, Texas USA
> /
> On 10/29/2011 7:39 PM, jonathan byler wrote:
>> Hi arnold,
>> the parts that were burned out never had kiln wash on them before,
>> so i
>> can't imagine that is what caused it. I put the kiln wash on the
>> brick
>> after the element had burnt out hoping to keep it from touching the
>> damaged brick. I was worried that the stuff on the brick might get on
>> the element again and burn it out. the only powder in there that I
>> can
>> see is from the ITC coating that I sprayed on the klin a few years
>> ago.
>> On Oct 28, 2011, at 5:22 PM, Arnold Howard wrote:
>>> Hi Jon,
>>> The kiln wash that you brushed onto the firebrick groove probably
>>> burned out the element. Though it is difficult to tell from the
>>> photo,
>>> the area of the burnout appears to be covered with firebrick powder.
>>> That can cause the element to overheat, too.
>>> Do you think the debris in the groove is firebrick powder?
>>> Sincerely,
>>> Arnold Howard
>>> Paragon Industries, L.P., Mesquite, Texas USA
>>> /
>>> On 10/27/2011 8:16 PM, jonathan byler wrote:
>>>> Hi Arnold,
>>>> The element burned out the same way as the previous ones (at
>>>> least it
>>>> looks the same). the firebricks looked like they had been
>>>> attacked by a
>>>> glaze drip where the element burned out, but blackish color. The
>>>> color
>>>> is the same as the ends of the element where it burned, so I am
>>>> thinking
>>>> either they got REALLY hot in one spot, or something got on them
>>>> and
>>>> fluxed them and they melted. whatever it is, it melted into the
>>>> brick
>>>> like a glaze run. unlikely that kiln wash got on that section of
>>>> the
>>>> element, but it is possible. I actually painted kiln wash (2/3
>>>> alumina
>>>> hydrate : 1/3 epk) onto the bricks where they were stained before
>>>> by the
>>>> previous element failures. the kiln wash that I applied to the
>>>> bricks
>>>> was to cover up the discoloration and hope that it would keep
>>>> whatever
>>>> caused the discoloration from touching the elements and ruining
>>>> them
>>>> again (if they were the culprit).
>>>> The stuff you see in this picture is bricks sprayed with ITC 100.
>>>> the
>>>> elements were in place (and new) when I sprayed the kiln a little
>>>> over
>>>> two years ago. the pinkish stuff on the elements is the remains
>>>> of the
>>>> ITC 100 - I think I got it a little thick on the elements and it
>>>> flaked
>>>> off again. I think that is what is responsible for the pinkish
>>>> tinge in
>>>> the element grooves. it is like this all around.
>>>> the only stuff falling into the kiln is crumbly bits from around
>>>> the
>>>> edge of the lid. there are sulfur/chrome compounds forming
>>>> between the
>>>> firebrick and the stainless steel covering where they touch. we
>>>> have had
>>>> a lot of off gassing problems with our clay since I have been
>>>> working
>>>> here and possibly before. it's possible that some of that stuff
>>>> fell
>>>> from the roof, but I can't see how it would fall sideways into an
>>>> element groove. I suppose I could try to place a bit of that
>>>> crumbly
>>>> stuff from the lid on part of the twisted together sections of the
>>>> temporarily repaired elements and see what happens.
>>>> -jon
>>>> On Oct 27, 2011, at 5:45 PM, Arnold Howard wrote:
>>>>> Hi Jon,
>>>>> Thanks for sending the picture of the burned out element.
>>>>> The area around the element break looks reddish. Is that firebrick
>>>>> powder? If not, what do you think it is?
>>>>> Is it possible that contaminants such as glaze or kiln wash
>>>>> particles
>>>>> are falling into the kiln? I have heard of this burning out the
>>>>> top
>>>>> elements. Someone brushed kiln wash off of the ware. The kiln wash
>>>>> landed into an element groove.
>>>>> Does the element have the same type of break as the other elements
>>>>> that burned out?
>>>>> Are the firebricks stained where the element burned out?
>>>>> Sincerely,
>>>>> Arnold Howard
>>>>> Paragon Industries, L.P., Mesquite, Texas USA
>>>>> /
>>>>> On 10/27/2011 5:12 PM, jonathan byler wrote:
>>>>>> Hi Arnold,
>>>>>> I had another of the elements blow on this kiln we have. I have
>>>>>> attached
>>>>>> a picture so you can see what happened. would have posted this to
>>>>>> clayart, but I couldn't put a picture up then.
>>>>>> This is the third of these to go out like this. the first two I
>>>>>> thought
>>>>>> had maybe gotten glaze on them. this one is almost at the top
>>>>>> of the
>>>>>> kiln and I can't see how a pot would have touched it, and I
>>>>>> have only
>>>>>> done one bisque firing since the last inspection of these
>>>>>> elements. I
>>>>>> didn't notice anything wrong with these before, and they weren't
>>>>>> reading
>>>>>> particularly high on my ohm meter. any thoughts? I had
>>>>>> considered that
>>>>>> maybe it was a bad element staple, but these elements have been
>>>>>> in
>>>>>> this
>>>>>> kiln for well over two years now without any problems until
>>>>>> recently. we
>>>>>> probably fire it on the high side about 48 times a year? maybe
>>>>>> 6 of
>>>>>> those total were up to about cone 6, and the kiln (a bailey) is
>>>>>> supposed
>>>>>> to be good for ^10.
>>>>>> Thanks for you help with this and of course all the good advice
>>>>>> you
>>>>>> give
>>>>>> on clayart.
>>>>>> -jon byler
>>>>>> auburn university art dept