Kiln Element Longevity.

[yedrow]

I've almost exclusively glaze fired with gas. I was wondering, how many firings at ^6 should one expect to get out of an element.

[Marcia Selsor]

this was originally posted may 2011

but I will repost it for you.

I read an analysis of element life by Linda Arbuckle that was interesting. She posted the different life spans depending on the temperatures fired.These are just numbers I am making up to illustrate what she said. It went something ilk this:

590 firing for bisque

300 for ^6 glaze

There were significant differences. ALso if you are firing down for a slow cool , you will probably shorten the element life If you have a sulfurous clay body or use glazes that burn off certain chemicals, that would also shorten your element life. If you protect your elements with a coating of ITC for metal, you may extend the element life

Marcia

[Guest JBaymore]

If you protect your elements with a coating of ITC for metal, you may extend the element life

 

The amount of extension of useful life will depend on how well the coating forms an absolutely perfect "ceramic shell" around the entire elements surface. Difficult to actually do and maintain when installing.

 

best,

 

...............john

[neilestrick]

Element life will vary greatly depending on how hot you fire. If you only ever fire to earthenware temps, your elements will last years. If you fire to cone 6, their lifespan goes down exponentially. I switched from cone 8 to cone 6 and got about 30% longer life out of my elements.

 

I tell my customers who fire to cone 6 to have me check their elements yearly. My production potter customers who fire a lot at cone 6 need new elements every 1-2 years. It's something that should be factored into operating costs. Elements for most round kilns are around $50 each. 27" tall kilns usually have 6 elements. Paying someone like me to do the work will cost about $500 total with parts and labor.

[yedrow]

Thanks folks, that was very helpful. Oh, and only rich potters can afford ITC, and from the looks of thing, Neil, lol.

[Mark C.]

While on the ITC info-It should be noted that a ITC was recently bought out and  new pricing went into effect August 1st-it went up about 1/3. I know this as I have a gallon sitting here that came that I ordered while at a show on the 30th of July before the increase.<div>I like the product for some applications.</div><div>Mark</div>

[Guest JBaymore]

Oh, and only rich potters can afford ITC, and from the looks of thing, Neil, lol.

 

While ITC is not the "snake oil" it is often cracked up to be, it DOES improve the emissivity of the typical refractory surface, and thereby does decrease firing costs by both decreased thermal transmission through the walls (keeps the wall surface temperature slightly lower) and particularly by improving radiational transfer to the load. It also evens out the firing a bit beacause of the latter, improving the wares and decreasing re-fires, seconds, or wasters.

 

So ITC pays for itself if you fire often. You can pay for it now... or pay fuel bills over time.

 

Yes, if you fire infrequently...... it is going to take a LONG time to recoup the investment.

 

best,

 

........................john

[BRL]

this was originally posted may 2011

but I will repost it for you.

I read an analysis of element life by Linda Arbuckle that was interesting. She posted the different life spans depending on the temperatures fired.These are just numbers I am making up to illustrate what she said. It went something ilk this:

590 firing for bisque

300 for ^6 glaze

There were significant differences. ALso if you are firing down for a slow cool , you will probably shorten the element life If you have a sulfurous clay body or use glazes that burn off certain chemicals, that would also shorten your element life. If you protect your elements with a coating of ITC for metal, you may extend the element life

Marcia

 

[BRL]

this was originally posted may 2011

but I will repost it for you.

I read an analysis of element life by Linda Arbuckle that was interesting. She posted the different life spans depending on the temperatures fired.These are just numbers I am making up to illustrate what she said. It went something ilk this:

590 firing for bisque

300 for ^6 glaze

There were significant differences. ALso if you are firing down for a slow cool , you will probably shorten the element life If you have a sulfurous clay body or use glazes that burn off certain chemicals, that would also shorten your element life. If you protect your elements with a coating of ITC for metal, you may extend the element life

Marcia

 

How do you apply ITC? Apply to elements only inside the kiln?

[Guest JBaymore]

fast answerr... on the way out the door.

 

Has to be on brand new elements before installing. The elements get fully cleaned, extended to the appropriate length, then fully dipped into the ITC metal coating. Then they are installed very carefully trying not to screw up the coating. Then the elements (and kiln element groove interior) are sprayed with a different ITC coating.

 

best,

 

......................john

[Marcia Selsor]

You should let the ITC dry before installing. Like hang them on a clothes line by the pony tail ends and let them dry so your fingers don't wipe off the ITC. If yoou use a long pan like a joint compound for sheetrock , you can dip them from one end to the other. Then hang and dry.

You need to clean the new elements. I think alcohol works but you can call Feriz and ask him. Or google it. Clayart discussed this about 10-15 years ago.

 

Marcia

[yedrow]

John, since you got all technical, I was wondering how ITC actually worked. My guess is that it changes the index of refraction in the infrared range. I know that IR can be changed by coatings, but I've only worked in the thin-film side of it, and that was years ago. What puzzles me is that if it is sprayed on the sides of a refractory substrate it apparently reflects radiant energy away. But on a metal substrate does it increases transmission? It doesn't seem to be applied thick enough to have any insulative value. Or, is it a blackbody of some sort? If so, I'm guessing there must be some destructive interference in the interface between the ITC and the refractory substrate. Hmm, I'm scratching my head. How does this stuff work?

[Mark C.]

While on the ITC thing I just noticed they shipped me the wrong kind-I have a gallon of 213 for metal coating instead of the HT 100 the paperwork says I ordered. Looks like ups will be back soon .

John is right on the lots of firing which is why it works for me. Its also great in the salt kiln.

 

Mark

[BRL]

fast answerr... on the way out the door.

 

Has to be on brand new elements before installing. The elements get fully cleaned, extended to the appropriate length, then fully dipped into the ITC metal coating. Then they are installed very carefully trying not to screw up the coating. Then the elements (and kiln element groove interior) are sprayed with a different ITC coating.

 

best,

 

......................john

 

[BRL]

ITC sounds as tricky as 'snake oil.' Thanks to all.

[LilyT]

John, since you got all technical, I was wondering how ITC actually worked. My guess is that it changes the index of refraction in the infrared range. I know that IR can be changed by coatings, but I've only worked in the thin-film side of it, and that was years ago. What puzzles me is that if it is sprayed on the sides of a refractory substrate it apparently reflects radiant energy away. But on a metal substrate does it increases transmission? It doesn't seem to be applied thick enough to have any insulative value. Or, is it a blackbody of some sort? If so, I'm guessing there must be some destructive interference in the interface between the ITC and the refractory substrate. Hmm, I'm scratching my head. How does this stuff work?

 

 

Hmm, I'm trying to get an understanding of this also. I think that we may be

looking at [at least] 2 different properties, IR Reflectance (as a function of

wavelength and perhaps temperature) and Emissivity (blackbody-like behavior).

 

Now that ITC is sold, maybe someone could talk a bit about what it's

actual properties are... shouldn't there be data sets with actual numbers

somewhere? (we're not asking for the secret formula, but if that's

available, that would help us break down the properties.)

 

A friend of mine who is a glass guy had this comment about our

question ... "the problem is when engineers and artists talk... :-)"

I guess maybe we don't speak the same language. I will follow

this topic and will post again if I get any further insight.

 

-Lily

[DAY]

You can, said the wise man, lengthen the life of you car by only driving at 25MPH.

If this 'stuff'- that has been around for some years now-is as good as they say, why aren't the kiln makers using it at the factory? Or at least offering it as an option- like L&L's heavy duty elements?

[yedrow]

I dig the technical and the art, Lily! I have been wondering about this for a while. The use of the term 'emissivity' suggests a blackbody type of material, but being a layman I expect such materials to be, well, black (at least at room temp.). I do know that some materials cause increases of refractive index at their interfaces (air-material, material-substrate). But in my experience that is thin-films at thicknesses measured in wavelengths of light. That being said, the reflectiveness of an object can be a matter of its surface, like the reflectiveness of polished aluminum. Such considerations put it in the realm of refraction. As well, if I remember right, a material can increase in reflection when the interface between mediums is air and the material (IFB) and increase transmission when the interface is between the material and the substrate (elements).

 

Emissivity though suggests that energy is taken in and emitted as infrared radiation, at least to this layman. That seems problematic though since we are talking about a bodies capacity to hold energy, at least to some degree. I would think that it would take more than the thin layer of material in a proper ITC coating to 'manage' the level of energy generated in a high temp. kiln. I'll admit though that I don't know a great deal about blackbodies. It's entirely possible that the scales are beyond my comprehension of the subject. I'm seeing this as excited molecules within a medium, and thus as electrons in metastable states of excitement. The duration of those states could be quite small.

 

Sorry if that gets kinda nerdy, its just that this question has been eating me alive, lol.

 

Joel.

[Mark C.]

John, since you got all technical, I was wondering how ITC actually worked. My guess is that it changes the index of refraction in the infrared range. I know that IR can be changed by coatings, but I've only worked in the thin-film side of it, and that was years ago. What puzzles me is that if it is sprayed on the sides of a refractory substrate it apparently reflects radiant energy away. But on a metal substrate does it increases transmission? It doesn't seem to be applied thick enough to have any insulative value. Or, is it a blackbody of some sort? If so, I'm guessing there must be some destructive interference in the interface between the ITC and the refractory substrate. Hmm, I'm scratching my head. How does this stuff work?

 

 

Hmm, I'm trying to get an understanding of this also. I think that we may be

looking at [at least] 2 different properties, IR Reflectance (as a function of

wavelength and perhaps temperature) and Emissivity (blackbody-like behavior).

 

Now that ITC is sold, maybe someone could talk a bit about what it's

actual properties are... shouldn't there be data sets with actual numbers

somewhere? (we're not asking for the secret formula, but if that's

available, that would help us break down the properties.)

 

A friend of mine who is a glass guy had this comment about our

question ... "the problem is when engineers and artists talk... :-)"

I guess maybe we don't speak the same language. I will follow

this topic and will post again if I get any further insight.

 

-Lily

 

 

Lily ITC is a proprietary formula ( its a BIG SECRET)

I had a gas spectrum analysis done on this stuff back in the 90's and learned very little but enough to start mixing my own salt coatings.

Which after years of testing works good.

My sense of this stuff is it reflects energy or at least slows down the energy absorption-thats why kiln shelves do not warp as fast-less heat work on them.

Back in the Day the owner of ITC said any good potter we let in the door of the back room would figure the formula out in a jiffy. That door was always off limits I'm told.

Its the same deal with Mars family chocolates-like snickers

Mark

[LilyT]

John, since you got all technical, I was wondering how ITC actually worked. My guess is that it changes the index of refraction in the infrared range. I know that IR can be changed by coatings, but I've only worked in the thin-film side of it, and that was years ago. What puzzles me is that if it is sprayed on the sides of a refractory substrate it apparently reflects radiant energy away. But on a metal substrate does it increases transmission? It doesn't seem to be applied thick enough to have any insulative value. Or, is it a blackbody of some sort? If so, I'm guessing there must be some destructive interference in the interface between the ITC and the refractory substrate. Hmm, I'm scratching my head. How does this stuff work?

 

 

Hmm, I'm trying to get an understanding of this also. I think that we may be

looking at [at least] 2 different properties, IR Reflectance (as a function of

wavelength and perhaps temperature) and Emissivity (blackbody-like behavior).

 

Now that ITC is sold, maybe someone could talk a bit about what it's

actual properties are... shouldn't there be data sets with actual numbers

somewhere? (we're not asking for the secret formula, but if that's

available, that would help us break down the properties.)

 

A friend of mine who is a glass guy had this comment about our

question ... "the problem is when engineers and artists talk... :-)"

I guess maybe we don't speak the same language. I will follow

this topic and will post again if I get any further insight.

 

-Lily

 

 

Lily ITC is a proprietary formula ( its a BIG SECRET)

I had a gas spectrum analysis done on this stuff back in the 90's and learned very little but enough to start mixing my own salt coatings.

Which after years of testing works good.

My sense of this stuff is it reflects energy or at least slows down the energy absorption-thats why kiln shelves do not warp as fast-less heat work on them.

Back in the Day the owner of ITC said any good potter we let in the door of the back room would figure the formula out in a jiffy. That door was always off limits I'm told.

Its the same deal with Mars family chocolates-like snickers

Mark

 

 

What, and you didn't peek, Mark, even to satisfy your own curiosity? :-)

Probably wise, they'd probably posted an armed guard on the lookout

for potters.

 

So you must tell us how you got gas chromatography done!

 

And whether you'd subjected the snickers bar to the same test...

 

And since I'm peppering you with questions tonight, won't you

give us any tempting details about the performance of your

top secret salt kiln coating, if only to make us salivate? And by

way of creating some media hype to shoo in your IPO, come

the day when you have time?

 

Curiously yours,

Lily

[LilyT]

I dig the technical and the art, Lily! I have been wondering about this for a while. The use of the term 'emissivity' suggests a blackbody type of material, but being a layman I expect such materials to be, well, black (at least at room temp.). I do know that some materials cause increases of refractive index at their interfaces (air-material, material-substrate). But in my experience that is thin-films at thicknesses measured in wavelengths of light. That being said, the reflectiveness of an object can be a matter of its surface, like the reflectiveness of polished aluminum. Such considerations put it in the realm of refraction. As well, if I remember right, a material can increase in reflection when the interface between mediums is air and the material (IFB) and increase transmission when the interface is between the material and the substrate (elements).

 

Emissivity though suggests that energy is taken in and emitted as infrared radiation, at least to this layman. That seems problematic though since we are talking about a bodies capacity to hold energy, at least to some degree. I would think that it would take more than the thin layer of material in a proper ITC coating to 'manage' the level of energy generated in a high temp. kiln. I'll admit though that I don't know a great deal about blackbodies. It's entirely possible that the scales are beyond my comprehension of the subject. I'm seeing this as excited molecules within a medium, and thus as electrons in metastable states of excitement. The duration of those states could be quite small.

 

Sorry if that gets kinda nerdy, its just that this question has been eating me alive, lol.

 

Joel.

 

 

hi, Joel!

 

I saved your wonderful post for last to respond to tonight because there's lots of good meaty stuff to

think about in here. You've certainly put a lot more (and better) thinking into it than I have (or may be

capable of, for that matter, eh?)

You know, this is going to drive me crazy, too, thinking about this, because now there's more to

wonder about. How is the energy transfer from the heat source to the walls/furniture moderated

by ITC? What is the mechanism by which real bodies absorb and emit energy across wavelengths?

That these interesting properties may be associated with coating thickness in a non-linear

way is also... interesting. And I'm too tired (or old) to think!

So, I'm in a wondering mood tonight... what's your background that you can mix the technical and

the art so fluently? And, if I may ask, what do you do (or have done), and where do you find

people to have conversations with mixing the science/tech and art? Don't be as mysterious as ITC please :-).

Do you work in an academic environment where you can get a master's student interested in

materials and art who needs a thesis topic?

I will show this thread to my husband, who is a physicist, maybe he can comment on your

thoughts and add to the fray.

 

Do you use ITC? What's your experience?

 

Looking forward to hearing your thoughts more,

Lily

[Marcia Selsor]

I use to get my ITC directly from Feriz and Alice, his wife. Alice and I talked for long times about growing up in NE Philadelphia.. we were about the same age. Unfortunately Alice died rather quickly from Breast cancer in the 1990s.. They were both very lovely and generous people. Feriz did invent ITC for industrial use but he also loved to see how artists and potters used it. Nils Lou gave a demo at NCECA once where he built a kiln out of plywood coated with ITC. It did work. I wouldn't use it for production, it merely demonstrated the insulating qualities of ITC. other uses used in advertising the material was patching a furnace wall with ITC coated plywood just to get the job done until further repairs could be made.

Some kiln companies will coat your new kilns and elements as part of a special order. I got two kilns that way about six years ago. It is an added expense , but I think it is worth it.

In the Mid to late1990s Feriz gave ITCto some of the techie folks on Clayart like Linda Blossum , Nils Lou and Mel Jacobson and other just to see how they used it.

Linda coated rods in her tile supports and said it prevented the rods from warping at high temperatures. she coated her burner tips to protect the metal from oxidizing.

And of course she sprayed the bricks inside her kilns.

 

You are suppose to dilute the ITC 100 with 50% water. I spray it with a sand blaster and usually have a drill with a mixer attachment stirring the solution at the same time I have the hose in the bucket for the sand blaster. I used it on the kilns where I taught both gas, electric, and soda kilns.

Marcia

[Guest JBaymore]

John, since you got all technical, I was wondering how ITC actually worked. My guess is that it changes the index of refraction in the infrared range. I know that IR can be changed by coatings, but I've only worked in the thin-film side of it, and that was years ago. What puzzles me is that if it is sprayed on the sides of a refractory substrate it apparently reflects radiant energy away. But on a metal substrate does it increases transmission? It doesn't seem to be applied thick enough to have any insulative value. Or, is it a blackbody of some sort? If so, I'm guessing there must be some destructive interference in the interface between the ITC and the refractory substrate. Hmm, I'm scratching my head. How does this stuff work?

 

 

Yedrow,

 

Sorry it took a while to get back to you.... busy.

 

Unfortunately, Ferez was very "protective" about the nature of the product as a proprietary formula. VERY! When he and I talked on a number of occasions he told me that it increased both reflectivity and emmisitivty of the wall surface. "Prying" into the workings was not effective <g>. He did not specifiy wavelengths, so I have to assume that it is mainly in the IR range.

 

You are right, the coating is applied so thinly that there is not appreciable "insulating value" even if the material was highly insulating. However, one thing it MAY do to improve energy consumption is tend to seal the micro-cracks in the brickwork that allow timy bits of hot gasses to leak out and air to infiltrate into the chamber. And in the case of being applied to refractory ceramic fiber, to help seal the highly porous fiber to the same factors....since many "potter usages" of fiber do not also involve a sealed steel shell encasing the fiber refractories to prevent this.

 

So-called "blackbody" radiation does not imply that the material must BE "black". The emissivity of different surfaces are being compared here....... the factors of ITC 100 HT versus those of insulating firebrick. The ITC can simply be better than the IFB while still not being a perfect radiator by any means. All it has to be is "better". And I do not know (scientifically tested) that is IS....... that is the just claim.

 

And when ITC 100 HT is applied to the typical highly rough pockmarked IFB surface it smooths it out greatly. So it is also possible that this smoothing action simply improves the surfaces reflectivity to IR and "bounces" more of the energy from the glowing radiative elements or flames into the stacking of ware.

 

So a slight improvement (over typical brickwork or rough surface fiber) in emmisivity, a slight improvement from sealing cracks, and a slight improvement in reflectivity might be all that there is involved here.

 

To bond to the substrates (brickwork or metal) the coating must interact in some manner with that material. Otherwise it would just flake right off. So yes.............there has to be some interaction between the two and a change to the developing interface layer of both compositions. When I've applied ITC 100HT it clearly makes a ceramic bond with the underlying brickwork.

 

The stuff on the metal elements is applied so thinly that there is minimal impact on the transmission through that extra coating over the normal oxide coating that forms anyway. Don't know for sure... but the transmission and emissivity factors for the ITC coating might actually be "better" than the same factors for the oxide coating that naturally forms on the metal when exposed to oxygen. At a highly technical level with lots of zeros after the decimal point, there HAS to be some impact from the ITC.... but likely so little as to be negligible in what we do.

 

It is basically acting as a "ceramic shell" to help protect the elements from whatever gasses happen to surround them. Likely you could get the same protection effect with any ceramic materials that you could get formulated to encase the elements into. In fact some industrial kilns actually embed the elements JUST inside the cast walls surface. So the main radiating surface is the refractory just to the chamber side of the element.... not the element itself.

 

To my knowledge no one has "reverse engineered" the product to see what it actually is. A materials analysis should be relatively simple with the right equipment available at a good university lab.

 

My own total GUESS on the 100 HT is that the carrier is simply a colloidal silica. And that the particulate contents involve both a zirconium compound and a silicon carbide compound. Then some fluxing material to make it bind to the substrate when fired.

 

Nor to my knowledge has anyone studied it at a highly "scientific level" (there's a project for someone, folks!). Some very basic "potter studies" have been done like checking energy consumption of a kiln before application and after, and that shows energy usage improvment. Not some astronomical "pie in the sky" thing, but significant. I've tested that factor once on a single unit......... and that test seems to indicate that it works. Maybe about 10-12% energy usage decrease on a test electric kiln. So significant.... but not earth shattering.

 

Most of the "data" out there in the handcraft pottery field that I have seen is apochrophal, and usually without good controls.

 

best,

 

..................john

[Mark C.]

Lily

I had friends at the science Dept at university who gas tested this.They could not reverse engineer it with the equipment they had.

 

John I would agree on your guess -the ITC material does have a binder which works well-I have no idea on what it is. His binder is great.

There are many types/forms of colloidal silicas and the ITC one seems different than my colloidal liquid -on say your hand

I got turned on to this stuff from Lou Niles and Mel Jacobson back in the day.

This stiff has a large particle mesh size thats why you need the sandblaster to apply.

Mark

[Guest JBaymore]

I had friends at the science Dept at university who gas tested this.They could not reverse engineer it with the equipment they had.

 

 

Really? Do you know what kind of equuipment they tried to use? Were these students or the faculty?

 

best,

 

................john