[Clayart] Extra insulation

[Edouard Bastarache via Clayart]

My friend Michel wants to know if it would a good idea to increase insulation on the cover and under his electric kilns, and why.

----- Original Message -----
From: Michel Lemire
To: Édouard Bastarache
Sent: Monday, December 29, 2014 5:01 PM
Subject: Économie, rendement énergétique, durabilité et longévité des matériaux

salut,
je ne sais pas si tu as déjà eu des discussions avec le fait du peu de souci d’isolation des fours céramiques opérant à l’électricité,
j’ai décidé de couvrir les extrémités (haut et bas) avec la laine: Ceramic Insulation Fiber 1” thickness (Kaowool) pour tenter de couper le temps de fonctionnement, les coûts énergétiques et pour conserver les paliers au besoin pour une meilleure uniformisation des glaçures du haut et du bas du four;
un avis des “gourous” céramiques serait apprécié et me signaler autres suggestions s’il y a lieu.
salutations,
Michel Lemire
MAILMAN_MIMEDEFANG WRAP
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[Paul Gerhold via Clayart]

First step have to be putting cones from top,to bottom of kiln several times while firing a load. That will tell him if insulation will improve the evenness of his firings. For energy usage insulating sides would help but has to go under the outside metal and is probably not worth the effort.

Paul

Sent from home

[Bill Schran via Clayart]

Edouard,
Most of the heat in top loading kilns is lost from the top and bottom, so that would be the reason to add additional insulation in these areas. One of the simplest ways would be to add an additional lid and bottom from an old salvaged kiln of the same diameter. One could use ceramic fiber blanket but this would need to be secured with some type of metal wire/fencing. Having the fiber blanket on top of the kiln lid could potentially be a health hazard were it not secured such that fibers are not disturbed and released. Perhaps rigid ceramic fiber might be better, such as this: http://armilcfs.com/refractory-products/ceramic-fiber/boards.html

Bill
---- Edouard Bastarache via Clayart <cla...@lists.clayartworld.com> wrote:

=============

My friend Michel wants to know if it would a good idea to increase insulation on the cover and under his electric kilns, and why.

----- Original Message -----
From: Michel Lemire
To: Édouard Bastarache
Sent: Monday, December 29, 2014 5:01 PM
Subject: Économie, rendement énergétique, durabilité et longévité des matériaux

salut,
je ne sais pas si tu as déjà eu des discussions avec le fait du peu de souci d’isolation des fours céramiques opérant à l’électricité,
j’ai décidé de couvrir les extrémités (haut et bas) avec la laine: Ceramic Insulation Fiber 1” thickness (Kaowool) pour tenter de couper le temps de fonctionnement, les coûts énergétiques et pour conserver les paliers au besoin pour une meilleure uniformisation des glaçures du haut et du bas du four;
un avis des “gourous” céramiques serait apprécié et me signaler autres suggestions s’il y a lieu.
salutations,
Michel Lemire
MAILMAN_MIMEDEFANG WRAP
_______________________________________________
Clayart mailing list
Cla...@lists.clayartworld.com
http://lists.clayartworld.com/cgi-bin/mailman/listinfo/clayart

MAILMAN_MIMEDEFANG

--
William "Bill" Schran
wsc...@cox.net
www.creativecreekartisans.com

[Snail Scott via Clayart]

On Jan 2, 2015, at 6:27 PM, Edouard Bastarache via Clayart wrote:
> My friend Michel wants to know if it would a good idea to increase insulation on the cover and under his electric kilns, and why.

I added insulation on top and under my electric kilns, and have
found the evenness of the firing to be noticeably improved. This
seems especially true of tightly packed loads.

I always loaded shelves spaced to avoid short distances between
the lowest shelf and the kiln-floor 'shelf', and between the top shelf
and the lid, when using multiple shelves. The logic of this is pretty
basic: the lid and floor have no elements in most kilns, so heat is not
added where it is lost; instead, it is added from the side elements of
the kiln. Heat is lost pretty equally everywhere, but only added from
the walls. If those top and bottom areas are walled off by shelves from
the main volume of the firing chamber, they will fire cooler than the rest.
Tightly-spaced shelves are OK in the middle levels, where they are
heated form the sides, and also by heat penetrating from above and
below. It's not OK at the top and bottom.

Most of my work is one piece per kiln, so I don't have the heat blockage
issue very often myself, but when I fire the occasional load of pottery
or tiles, it becomes very obvious.

I use a lid from my old 'beater' kiln under the floor of my main electric
kiln, permanently. It not only keeps the floor from firing cool, but allows
me to use a shorter kiln stand - enough to lower the height of the top
edge in spite of the thicker bottom - a few inches difference is a big
help to someone as short as I am, and saves me having to unstack
the kiln more often than I do.

I have 1" thick refractory fiberboard cut to fit the top, but I mainly use
it when I am stacking with multiple shelves for tiles, etc. (Just lazy -
it's never a bad thing to use it!) Keeping the extra insulation on the
bottom matters more to me. First, the aforementioned height reduction.
Second, the fact that my work, when loaded, doesn't always block the
heat from reaching the top near the lid, but it's almost always going to
be sitting on the floor shelf creating its own heat blockage at the
botttom. Third, odds are that the kiln is a bit leaky, and if so, even
minimal convection will result in heat rising and cooler air falling to
the bottom. Fourth; I ain't unstacking that puppy just to get the extra
insulation out from under it when it's not needed! :-)

-Snail

[David Woof via Clayart]

The kiln sides were not in the original question, but if the side metal is stainless, AKA "stainless steel" one may wrap the exterior of the existing metal shell with ceramic fiber because stainless steel can withstand temperature upwards plus/minus of 1700 f. Of course one would no doubt wish to wrap another metal or expanded metal jacket around the new exterior to secure the fiber. Quick fix re the shedding of exterior fiber is to spray the fiber surface with high temp auto exhaust manifold paint to lock the fibers.. Works like a trick.
***Use all known and published safety precautions when working with fiber material or you may cough up your lungs some day.***
David Woof****************************************

> Date: Sat, 3 Jan 2015 08:30:14 -0500
> To: edou...@colba.net; cla...@lists.clayartworld.com
> Subject: Re: [Clayart] Extra insulation
> From: cla...@lists.clayartworld.com

[Jim Brown via Clayart]

"My friend Michel wants to know if it would a good idea to increase

insulation on the cover and under his electric kilns, and why." - Edouard

Short answer, heat rises so top is a great idea.

But think of a kiln as just a vessel to hold heat - more heat in, less heat
out and the temp goes up. The less heat that is lost through the top,
bottom and walls the less energy needed to reach temp and the faster it
will reach that temp.

Adding more insulation anywhere will make a big improvement in holding that
heat in. But wrapping a kiln with fiber everywhere would be an outstanding
idea. Only downside, fiber is not cheap. Doing top is best bang for the
buck if one can't do it all.

* JIM BROWN*

* Brown's Pottery Hiddenite*

* "Making handmade pottery . . . *

* . . . since the 1700's" *
* 386 479-4515*
* www.brownpotters.com <http://www.brownpotters.com>*

[Jim Brown via Clayart]

"For energy usage insulating sides would help but has to go under the

outside metal and is probably not worth the effort." - Paul

OK - I give, Why?

[Jim Brown via Clayart]

" Perhaps rigid ceramic fiber might be better, such as this:

http://armilcfs.com/refractory-products/ceramic-fiber/boards.html" - Bill

Wow - I had not checked the price of fiber in many years. I am sitting on
a gold mine - I have over a pickup load of both fiber batts and rolls I
have had for over 30 years. Also hundreds of soft insulating brick. I
have built several kilns over the years, taken then down and re-used the
material.

I cut some 2" batts the size of the top of the kiln and lay them on top.
Also cut some the size of shelves and use them for the top shelve - so far,
no problem with warping but I don't put too much weight on them. And also
use one as the top cover shelve in the Torchbearer kiln - put that about
1.5 to 2 inches from the top to hold more heat from going out the top too
fast.

* JIM BROWN*

* Brown's Pottery Hiddenite*

* "Making handmade pottery . . . *

* . . . since the 1700's" *

* 386 479-4515 <386%20479-4515>*

[Joe Brecha via Clayart]

Do not cover the metal of your electric kiln with fiber. This will kill
your kiln skin. Do not do it!

[Vince Pitelka via Clayart]

Edouard wrote:
"My friend Michel wants to know if it would a good idea to increase insulation on the cover and under his electric kilns, and why."

Hi Edouard -
Increasing insulation atop the lid is easy, but if you want to increase the insulation on the sides of a toploader electric kiln it must be done beneath the metal jacket. It is not that big a deal to remove the metal jacket and fabricate an extension from stainless steel sheet metal so that it will fit around the kiln with the new insulation in place. If your controller box is mounted in the surface of the kiln you would have to remount that farther out, and that could get into real complications. If you insulate outside the metal shell, it will overheat and fail quickly. If you add insulation in such a way that it blocks off any air circulation around and through the controller box, it could cause electrical components to overheat, and then you'll have expensive repairs.
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpit...@dtccom.net
http://iweb.tntech.edu/wpitelka/

[Paul Gerhold via Clayart]

Well because I actually added a layer of fibre to the outside of my Paragon and the stainless disintegrated at an amazing rate. The Skutt next to it with no extra insulation stayed in great shape. Maybe the Skutt had a better grade of stainless but probably not. My guess is that the insulation on the outside either trapped some of the corrosive gasses next to the stainless or trapped more moisture against the stainless, or both.

If anyone wants to verify my unfortunate experiment with their own kiln I would be curious about the results. My recollection is it took about three years to turns the stainless to a total mess. Course I only found this out when it became necessary to take the kiln apart.

Paul

Sent from home

[Jim Brown via Clayart]

Paul, when I posted I didn't think of the older kilns not having stainless
around them - they will, of course, deteriorate quickly. Ref your last,
are you sure it was stainless and not aircraft grade aluminum? No matter
the grade, aluminum will not stand up - I would think the stainless would
not be a problem.

[Jim Brown via Clayart]

The post about overheating the electronics is important to remember. I
would think it a good idea if kiln makers added a small fan inside them
anyway but certainly if one puts insulation where it would block air flow.
Just aiming a small house fan at the electronics would work and I think
would be a good idea at any rate - especially computer controlled kilns.

[Joe Brecha via Clayart]

Stainless is a problem. This does not work. The metal degrades quickly. Joe
Brecha

-----Original Message-----
From: Clayart [mailto:clayart...@lists.clayartworld.com] On Behalf Of

[Paul Herman via Clayart]

Jim,

Stainless kiln skin will not hold up to wrapping in fiber and firing. It turns into a warped, scaly rusty mess. don’t do it.

Paul Herman

Great Basin Pottery
Doyle California
greatbasinpottery.com
potte...@frontiernet.net

[Paul Gerhold via Clayart]

Well they sold it as stainless. My cradles that I used to lift really large Raku in and out of the electric kiln were built from 3/16 stainless and they showed signs of disintegrated over time. There are many grades of stainless.

A friend of mine builds large stainless sculptures and found out the hard way that the grade of stainless he was using didn't do well near salt water.

Paul

Sent from home

[Paul Gerhold via Clayart]

I don't use electronic controlled kilns but on my antiques I added angle brackets to move the control boxes another 2 inches away from the kiln heat.

Paul

Sent from home

[L TURNER via Clayart]

Joe,

Can you explain why please?

LT

[Vince Pitelka via Clayart]

Joe Brecha explained that the stainless will degrade quickly if you put insulation outside the jacket on a toploader electric kiln, and Lou Turner asked him to explain why.

Lou -
Joe is right, and he might be able to explain why it happens, but I cannot. I have just seen it happen several times. As you know, there are many different kinds of stainless steel, and the one on kilns works fine as long as it doesn't get too hot. But when it does get too hot (as when someone puts additional insulation outside the stainless), perhaps in combination with the corrosive gases produced by the kiln, it does degrade quickly.
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpit...@dtccom.net
http://iweb.tntech.edu/wpitelka/

[Eva Gallagher via Clayart]

When I bought some stainless steel pins to reinforce some castable for my
kiln the engineer at RHI mentioned that it probably was not a good idea to
use them if there is a reducing atmosphere - I think that you probably get
a reducing atmosphere around the steel when the you cover the steel with
insulation - with the heat the gases given off from the kiln burn but
probably not good oxygen turnover.
Eva Gallagher
Deep River, Ontario
http://newfoundoutpotter.blogspot.com/

----- Original Message -----
From: "Vince Pitelka via Clayart" <cla...@lists.clayartworld.com>
To: "'L TURNER'" <magnolia...@gmail.com>; "'Clayart international
pottery discussion forum'" <cla...@lists.clayartworld.com>;
<j...@clayartcenter.net>
Sent: Monday, January 05, 2015 3:37 PM
Subject: Re: [Clayart] Extra insulation

[Bill Schran via Clayart]

I don't imagine kiln makers use the most expensive and corrosion resistant type of stainless steel and would expect if the stainless steel skin of a kiln were wrapped in insulating fiber the combination of heating and corrosive fumes from the firing would degrade it rather rapidly. Out of curiosity I looked up types of stainless steel and found this: http://www.bosunsupplies.com/StainlessInfo2/
Perhaps Arnold might chime in and advise what type stainless kiln makers use.
Bill

---- Paul Herman via Clayart <cla...@lists.clayartworld.com> wrote:

=============
Jim,

Stainless kiln skin will not hold up to wrapping in fiber and firing. It turns into a warped, scaly rusty mess. don’t do it.

Paul Herman

Great Basin Pottery
Doyle California
greatbasinpottery.com
potte...@frontiernet.net

On Jan 5, 2015, at 8:23 AM, Jim Brown via Clayart <cla...@lists.clayartworld.com> wrote:

> Paul, when I posted I didn't think of the older kilns not having stainless
> around them - they will, of course, deteriorate quickly. Ref your last,
> are you sure it was stainless and not aircraft grade aluminum? No matter
> the grade, aluminum will not stand up - I would think the stainless would
> not be a problem.
>
>
> * JIM BROWN*
>
> * Brown's Pottery Hiddenite*
>
> * "Making handmade pottery . . . *
>
> * . . . since the 1700's" *
> * 386 479-4515*
> * www.brownpotters.com <http://www.brownpotters.com>*

> MAILMAN_MIMEDEFANG WRAP
> _______________________________________________
> Clayart mailing list
> Cla...@lists.clayartworld.com
> http://lists.clayartworld.com/cgi-bin/mailman/listinfo/clayart
>
> MAILMAN_MIMEDEFANG

MAILMAN_MIMEDEFANG WRAP
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--

William "Bill" Schran
wsc...@cox.net
www.creativecreekartisans.com

[Hank Murrow via Clayart]

On Jan 5, 2015, at 1:50 PM, Eva Gallagher via Clayart <cla...@lists.clayartworld.com> wrote:

> When I bought some stainless steel pins to reinforce some castable for my kiln the engineer at RHI mentioned that it probably was not a good idea to use them if there is a reducing atmosphere -

Now we ARE getting a bit off-topic here. I am confused at your engineer's suggestion that reducing atmospheres would damage the pins. I have used Stainless Alloy "RibTek" or RibCon" needles in the castable base of my Doorless Fiberkiln for 35 years without deleterious effects. The needles are crimped and hold the castable together when the inevitable cracks form. This is a very different application than the one discussed in the original thread, and deserves a separate thread for discussion if there is ongoing interest.

Cheers, Hank in Eugene

[Fredrick Paget via Clayart]

The problem with insulating an existing kiln with a wrapper of kao
wool fiber is that the wool is a better insulator than the firebricks
and you must consider the make up of the kiln wall with 2400 degrees
F on the inside and maybe about 150 degrees on the outside. There
will be a drop in temperature through the wall . It can be
calculated. Engineers would do that and get the temperature at the
boundries of the bricks the SS shell and the fiber. That is not the
kind of engineering I did when I was working so I don't know how off
the top of my head. I bet though that the steel would get up to
around 1000 degrees and that is red heat.

There are dozens of different alloys called "stainless steel" and
some can take a lot of heat. There are hastelloy aloys that would
work in that environment but they are not stainess steel as there is
very little iron in them. And they are very expensive.

If you want to insulate a kiln, take off the stainless wrapper,
insulate it and put back the stainless wrapper and you will find it
too short but the gap can be filled with a patch of stainless steel
and it should work. Now you will have a kiln similar to mine which is
a Cone Art that is made with 1 inch of insulating bat over the bricks
inside the shell. It is avalable for purchase.You will find that
instead of cooling down overnight like a Scutt, that it takes two
days to cool down from hifire temps. That is aggrevating.

Fred Paget
--
Twin Dragon Studio
Mill Valley, CA, USA

[Ivor Lewis via Clayart]

For those of you who wish to advance your knowledge of metallurgical science
I suggest reading "Metals in the service of Man". William Alexander and
Arthur Street" published by Pelican.
My own experience with 18Cr-8Ni group was that high rates of corrosion could
be expected at ambient temperatures along welded seams of un-stabilised
metal. This effect was observed in unstable metal used to make fermentation
vessels. Alongside all welded seams the metal was deeply etched by raw
un-distilled whisky.
If you need a heat resistant alloy select one from the Stellite Range of
Cobalt Alloys (Deloro Canada)
All the best,
Ivor Lewis.

[Paul Gerhold via Clayart]

You need to use inconel.

Paul

Sent from home

[Arnold Howard via Clayart]

On 1/5/2015 12:25 PM, Paul Gerhold via Clayart wrote:
> I don't use electronic controlled kilns but on my antiques I added
> angle brackets to move the control boxes another 2 inches away from
> the kiln heat.
>
> Paul

If the kiln's switch box gets too hot, you can significantly reduce the
temperature of the switch box with 1/4" stand offs. They are small tubes
that slide between the switch box and kiln case where the screws are
inserted.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
aho...@paragonweb.com / www.paragonweb.com

[Arnold Howard via Clayart]

On 1/3/2015 4:10 PM, Vince Pitelka via Clayart wrote:
Increasing insulation atop the lid is easy, but if you
> want to increase the insulation on the sides of a toploader electric
> kiln it must be done beneath the metal jacket. It is not that big a
> deal to remove the metal jacket and fabricate an extension from
> stainless steel sheet metal so that it will fit around the kiln with
> the new insulation in place.

After adding ceramic fiber blanket between the firebrick walls and the
stainless steel case, you will notice that the edge of the blanket shows
at the top of the case. To cover that edge, slide a ceramic rope between
the stainless case and the firebrick walls. The ceramic rope will cover
the fiber blanket.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
aho...@paragonweb.com / www.paragonweb.com

[Paul Gerhold via Clayart]

I just did it with a few pieces of angle iron and some bolts and sheet metal screws that were lying aground. Just went a lot farther than 1/4" since I was doing it anyway.

Paul

Sent from home

[Eva Gallagher via Clayart]

Hi Hank,, Paul - my pins are crimped as well - they are about 1' long. I
bought them at the same place as the insulating castable. The name Inconel
rings a bell but not sure if the pins were made of that. I was to use them
in casting 4" thick slab lids for my train kiln but ended up not using the
pins as was told that probably they would not hold up to the hot temps and
redux. I thought that if they ended up coroding then I would end up with
empty spaces which would end up weakening the slab.
Anyway the slabs after about 12 firings are beginning to crack so will have
to replace soon with something else or a different castable. I have also
used high alumina shleves coated with ITC as well as 4" thick hard brick
slabs (about 12 x 24) and both of these are cracking too:(
Probably have been bringing the temp up too fast:(
Eva Gallagher
Deep River,Ontario
http://newfoundoutpotter.blogspot.com/

--- Original Message -----
From: "Hank Murrow" <hmu...@efn.org>
To: "Eva Gallagher" <ga...@magma.ca>; "Clayart international pottery
discussion forum" <cla...@lists.clayartworld.com>
Sent: Monday, January 05, 2015 6:14 PM
Subject: Re: [Clayart] Extra insulation

[Eleanora Eden via Clayart]

Hi All,

My late husband installed a little fan from radio shack on the side of
the control panel.
When I replaced the control panel with a brand new one I didn't know
how to do that,
so I am using two little 6" fans taped to the top of the panel,
directed down into the box.
Works fine.

As for the added insulation, we added a layer of kaowool blanket all
around the
kiln and wrapped that with chicken wire. Then spread a layer of
cement used
for chimneys. It has worked fine, since late '80s. The idea of
worrying whether
the metal sheathing is affected is not an issue. Not like I am
selling this kiln, or
moving it. This is a kiln that comes in sections and I know the heat
savings
is big.

Now for the lid, I have 2 lids that I add on top of the main one. The
top of the kiln
gets warm, never hot.

So, this is something that has worked well for me for a long time.

Eleanora