barblund on fri 8 apr 05
I wanted to get a kiln with more insulation than the regular round =
kilns, but the company I wanted to get it from took the space out of the =
inside of the kiln when they made their thicker model. I do not =
understand why cutting the stainless steel jacket a few inches larger to =
accommodate extra brick or fiber on the outside is so hard? I know it =
is more complicated than that, but... I was willing to pay the extra $ =
for a better insulated kiln, but the manufacturer made the insides =
smaller and that would mean making smaller plates, and casseroles(4 fit =
on the shelf just fine but wouldn't with the space taken out of the =
middle) and getting new kiln shelves as well. I really like the kilns =
this company makes and didn't want to go with another brand so I had to =
settle for the old style kiln which heats up the kiln room way too much- =
even with a kaowool blanket put on top to help keep the heat in!
so there are thicker brick customers out there- the kiln makers just =
have to be aware of the potters desires! I have discussed this with the =
owner of the kiln company.
Barb from Bloomington
heading off to Philadelphia next weekend to see the Dali exhibit!
barblund@bluemarble.net
520 West 6th St.
Bloomington, IN 47404
812 339 8476
Craig Clark on sat 9 apr 05
Barb, this issue has come up on the list before and has been
responded to by at least one of the folks in the kiln building business.
THe story was basically that a few years back there was an effort to go
ahead and produce a more well insulated kiln but that there just weren't
enough folks willing to cough up the exrta bucks to buy them.
As an alternative, and one I'm going to try, there have been several
people who have used the fiber blanket to not only cover the top of
their kilns but also as a wrap around the insulating bricks. The blanket
is applied to the bricks and then the stainless jacket is placed over it
by using threaded rod in place of the shorter bolts which are no longer
long enough do to the expanded circumference from the blanket. If you
check the archives I believe there are some specific instructions. One
thing not to do is to put the blanket over the steel. It will end up
causing the steel to heat repeatedly and will eventually fail.
Additionally, it seems that the ITC products work wonders in
increased firing efficiency. HTC 100 at a minimum is a good way to go.
Potters have been slow to embrace the product but industry has certainly
taken off running with it.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
John Rodgers on sat 9 apr 05
I am getting ready to rebuild my old Crusader and I too wanted to get=20
some kind of greater heat efficiency out of the kiln. It is a cone 10=20
kiln,, and has the thicker bricks anyway, and has a sheet of insulating=20
fiber between the bricks and the stainless sheet wrapped around the out =
side. This kiln is very old and the bricks are crumbling badly thus the =
need to rebuild it. It is a very large diameter kiln and becasue of that =
I have decided to custom order the new bricks cut to lay flat instead of =
on edge as is the kiln building tradition. This is going to make it=20
heavier as there are going to be more bricks in the kiln, but instead of =
3 inch thick wall it will now have 5 inch walls - or there abouts -=20
given whatever the width of a brick is.
The Crusader is basically a shell with a separate flat bottom, The lid=20
is attached to a hinge on the metal jacket. This construction allows me=20
to play with it a bit to get it just the way I want it. I am having a=20
metal frame made and will build a new bottom that the shell just sits=20
on. The bottom will be one layer of hard brick and on top will be one=20
layer of K-26 insulated brick. I have not resolved the new lid=20
construction yet, but it too will be thicker.
I plan to use ITC on the interior, and also rig this kiln out for the=20
combo electric/gas for reduction firing. But it will definitely be able=20
to get to Cone 10 without any strain.
With the very large diameter of this kiln, I will not suffer any=20
significant loss of interior space.
Regards,
John Rodgers
Chelsea, AL
barblund wrote:
>I wanted to get a kiln with more insulation than the regular round kilns=
, but the company I wanted to get it from took the space out of the insid=
e of the kiln when they made their thicker model. I do not understand wh=
y cutting the stainless steel jacket a few inches larger to accommodate e=
xtra brick or fiber on the outside is so hard? I know it is more complic=
ated than that, but... I was willing to pay the extra $ for a better insu=
lated kiln, but the manufacturer made the insides smaller and that would =
mean making smaller plates, and casseroles(4 fit on the shelf just fine b=
ut wouldn't with the space taken out of the middle) and getting new kiln =
shelves as well. I really like the kilns this company makes and didn't =
want to go with another brand so I had to settle for the old style kiln w=
hich heats up the kiln room way too much- even with a kaowool blanket put=
on top to help keep the heat in!
>
>so there are thicker brick customers out there- the kiln makers just hav=
e to be aware of the potters desires! I have discussed this with the own=
er of the kiln company.
>
>Barb from Bloomington
>
>heading off to Philadelphia next weekend to see the Dali exhibit!
>
>barblund@bluemarble.net
>520 West 6th St.
>Bloomington, IN 47404
>812 339 8476
>
>________________________________________________________________________=
______
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pcli=
nk.com.
>
>
> =20
>
Michael Wendt on sat 9 apr 05
Barb,
Several factors come into play here.
1) Precut stainless steel sheet comes in 8' and 10' lengths. The other
choice is a huge continuous roll and if the manufacturers get this size, it
might actually be cheaper in the long run. Maybe they already do.
2) Stock bricks are 9" x 4.5" x 2.5" or 3" so this controls the maximum
outer diameter of the kiln. They don't want a small wedge missing at each of
the junctions. Increasing the OD would require longer specialty bricks.
3) Fitting through doors. Imagine you get the kiln home and can't get it
into the house. Making it in sections can help in this regard but then you
have electrical connections to contend with.
4) Cost: Most people are looking for the cheapest kiln they can get. They
look at the initial purchase price because the higher electrical cost is
spread out over many years and is covered more or less by the revenue
generated at the time by the actual firing.
These are only some of the reasons the size was removed from the inside.
Only if almost all purchasers request the heavily insulated versions so that
their volume was high enough will they appear in more supply houses.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Barb wrote:
I was willing to pay the extra $ for a better insulated kiln, but the
manufacturer made the insides smaller and that would mean making smaller
plates, and casseroles(4 fit on the shelf just fine but wouldn't with the
space taken out of the middle) and getting new kiln shelves as well. I
really like the kilns this company makes and didn't want to go with another
brand so I had to settle for the old style kiln which heats up the kiln room
way too much- even with a kaowool blanket put on top to help keep the heat
in!
so there are thicker brick customers out there- the kiln makers just have to
be aware of the potters desires! I have discussed this with the owner of
the kiln company.
Barb from Bloomington
pdp1@EARTHLINK.NET on sat 9 apr 05
Hi Barb,
I would think, that so long as one accomidates the area of
the controll box attatched to the side, and does not intend
to seperate routinely the stacked rings of Bricks, I see no
reason why any approximately 'roundish', 'hexagon' or the
likes ( or square for that metter, if with a little more
sheet metal bending ) of electric Kiln could not have it's
sheet metal jacket removed, have as much additional
insulation as one wants added to the outside, and for the
sheet metal jacket to be added to, or augmented, to surround
the new diameter nicely.
Nor would the additional sheet metal for the jacket have to
be Stainless Steel per-se, for that matter, but could be
plain steel of some appropriate gauge held overlapping and
in addition to the gap of the old jackets' ends, with the
whole snugged up with some tightenable thin straps, so no
welding or riveting or other physical fastening of the old
jacket to the new gap-spanner would be necessary.
Phil
el ve
----- Original Message -----
From: "barblund"
I wanted to get a kiln with more insulation than the regular
round kilns, but the company I wanted to get it from took
the space out of the inside of the kiln when they made their
thicker model. I do not understand why cutting the
stainless steel jacket a few inches larger to accommodate
extra brick or fiber on the outside is so hard? I know it
is more complicated than that, but... I was willing to pay
the extra $ for a better insulated kiln, but the
manufacturer made the insides smaller and that would mean
making smaller plates, and casseroles(4 fit on the shelf
just fine but wouldn't with the space taken out of the
middle) and getting new kiln shelves as well. I really
like the kilns this company makes and didn't want to go with
another brand so I had to settle for the old style kiln
which heats up the kiln room way too much- even with a
kaowool blanket put on top to help keep the heat in!
so there are thicker brick customers out there- the kiln
makers just have to be aware of the potters desires! I have
discussed this with the owner of the kiln company.
Barb from Bloomington
Gary Lee on sun 10 apr 05
Craig writes:
As an alternative, and one I'm going to try, there have been several
people who have used the fiber blanket to not only cover the top of
their kilns but also as a wrap around the insulating bricks. The blanket
is applied to the bricks and then the stainless jacket is placed over it
by using threaded rod in place of the shorter bolts which are no longer
long enough do to the expanded circumference from the blanket. If you
check the archives I believe there are some specific instructions. One
thing not to do is to put the blanket over the steel. It will end up
causing the steel to heat repeatedly and will eventually fail.
This sounds like a great solution but has it drawbacks. Fiber insulation
works because of the air pockets in the fiber. If you wrap the kiln in a fiber
blanket, then wrap the steel back around the kiln, you compress the fiber which
reduces the insulating property of the fiber. Not to mention that unless you
tighten the bolts down tight enough now your bricks are loose. I am not sure
what type of insulating fiber the kiln company that tried that was using but
it may have been a type of rigid foam insulation which would work without
compressing. The idea to ramp down slow with computer kilns or reset the kiln
setter with one or more switches on low for an hour or so is probably the best
way to do it. As to wrapping the fiber blanket around the outside of the kiln,
I am unsure how that would cause the stainless steel to fail? Stainless is
designed for the high temperatures it is exposed to from the kiln firing. That
is why they use it. The outside of a kiln firing to cone 6 will be about 150
degrees or slightly more. Wrapping a fiber blanket around it would increase
the temperature by only about 50 - 75 degrees more which will be well within
the tolerance level of the stainless steel.
The idea that was posted to stay with your glazes as they are at the
temperature you now fire and the rate of cool down is good advice. I have two
KS-1027's and one KM-1227 and fire them each over 110 times a year. Our glazes turn
out constant with each firing. With no holds or ramp downs. This works for
me but experiment, experiment, experiment is always fun.
Gary
Rising Sun Pottery
In beautiful, everything is blooming, it's Spring in NC.
Vince Pitelka on sun 10 apr 05
> As to wrapping the fiber blanket around the outside of the kiln,
> I am unsure how that would cause the stainless steel to fail? Stainless
> is
> designed for the high temperatures it is exposed to from the kiln firing.
> That
> is why they use it. The outside of a kiln firing to cone 6 will be about
> 150
> degrees or slightly more. Wrapping a fiber blanket around it would
> increase
> the temperature by only about 50 - 75 degrees more which will be well
> within
> the tolerance level of the stainless steel.
Gary -
Having seen this attempted, I can attest to the destructive effect. First,
the outside of an electric kiln with only 2.5" of IFB often gets hot enough
to burn instantly. I have not measured the surface temperature, but would
guess it to be in the 350-400 degree Fahrenheit range. The only reason it
doesn't get hotter is that convection causes constant air circulation over
the surface. When you eliminate that air circulation by adding a layer of
superior insulation outside the stainless shell, you hold in the heat that
is coming through the brick, and the stainless jacket would get up to red
heat, especially adjacent to the element grooves, where the brick is much
thinner.
Repeatedly reaching red heat might not hurt the stainless steel itself, but
it would quickly destroy the screws and fixtures that hold the stainless
shell together, mount the lid, mount the control boxes, etc.
Regarding your other comments about adding a layer of fiber beneath the
stainless jacket, it is true that using rigid fiber insulating board would
be a superior solution, but using the fiber works very well also. The
compressive force of the stainless steel shell does mash the fiber down
quite a bit, but it is still a vastly superior insulation as compared to the
IFB, and a thin layer of compressed fiber makes a big difference. Remember
that in Z-block and other accordion-fold fiber installation methods, the
fiber is under considerable compression.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Arnold Howard on mon 11 apr 05
Paragon makes a kiln with the bricks turned sideways. Each row of bricks has
one element groove. The walls are 4 1/2" thick. It is designed for crucible
glass artists who maintain a temperature of 2200 deg. F continuously, for
weeks at a time.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
----------------
From: "John Rodgers"
I am getting ready to rebuild my old Crusader and I too wanted to get
some kind of greater heat efficiency out of the kiln. It is a cone 10
kiln,, and has the thicker bricks anyway, and has a sheet of insulating
fiber between the bricks and the stainless sheet wrapped around the out
side. This kiln is very old and the bricks are crumbling badly thus the
need to rebuild it. It is a very large diameter kiln and becasue of that
I have decided to custom order the new bricks cut to lay flat instead of
on edge as is the kiln building tradition. This is going to make it
heavier as there are going to be more bricks in the kiln, but instead of
3 inch thick wall it will now have 5 inch walls - or there abouts -
given whatever the width of a brick is.
James and Sherron Bowen on mon 11 apr 05
I think that air pockets being the main factor in the insulating properties
of materials is generally true, but the literature I have seen on ceramic
fiber talks more about its ability to reflect heat than about trapping air.
JB
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