Nan Rothwell on sun 22 dec 96
This is in response to the question about soft bricks in salt kilns. I have
been firing salt for nearly 20 years and during that time have tried a number
of combinations of low-quality used firebrick, new and expensive hard brick,
softbrick, castable, etc. This is not to suggest I'm an expert on kilns --
I'm NOT. But I can share some of my hit and miss results. In my experience,
the only softbrick that holds up well to repeated saltings is the K23 brick
originally made by Babcock and Wilcox. That brick is now available from
Thermal Ceramics in Augusta -- phone 706-796-4200 and they can give you a
local supplier. (I got this info from Clayart -- thanks Heather!) I looked
into the promotional literature from ITC, but don't know how ITC coatings
would hold up to salt. But if I wanted to experiment with it, I would
certainly start by building the basic wall with the Thermal Ceramics brand
K23 brick. (A warning: B&W used to make higher grades bricks too, and I
suspect that Thermal Ceramics still does. BUT only their K23's did well in
salt.)
As a gross generalization, I have found that high-alumina formula products
which are formulated to "resist" salt have not stood up well during repeated
firings. Over the years, I have tried special shelves and a variety of kiln
furniture. What generally seems to happen is that the surface resists salt
nicely, but the interior binders break down over time. So the products
remained beautifully clean on the surface, but lost their structural
strength. (I m just guessing that it was the binders that broke down -- I
can only tell you for sure that they got soft and crumbly.) I have tried
several high-alumina castables inside salt kilns, some commercially
available, some homemade. They reacted the same way the shelves did -- e.g.,
they resisted salting and stayed clean-looking; but they lost their
structural integrity. In fact, the castables all expanded over repeated
saltings. The fireboxes and bottom of my first kiln expanded so much they
bent the iron corner-bracing and eventually pushed out so far that I had to
take the kiln down. These days, I stick with high-quality hard brick for
anything structural in my kilns. But when I was recently resurrecting my
old salt kiln, I did buy some beautiful new Thermal Ceramics K-23's for the
door. I'm still enjoying the luxury of bricking up the door with so many
unbroken bricks!
Hope this helps!
Nan Rothwell
In Nelson County, Virginia where it is 18 degrees and windy...
Brooks Burgess on mon 23 dec 96
At 11:05 AM 12/22/96 EST, you wrote:
>----------------------------Original message----------------------------
>This is in response to the question about soft bricks in salt kilns. I have
>been firing salt for nearly 20 years and during that time have tried a number
>of combinations of low-quality used firebrick, new and expensive hard brick,
>softbrick, castable, etc. This is not to suggest I'm an expert on kilns --
>I'm NOT. But I can share some of my hit and miss results. In my experience,
>the only softbrick that holds up well to repeated saltings is the K23 brick
>originally made by Babcock and Wilcox. That brick is now available from
>Thermal Ceramics in Augusta -- phone 706-796-4200 and they can give you a
>local supplier. (I got this info from Clayart -- thanks Heather!) I looked
>into the promotional literature from ITC, but don't know how ITC coatings
>would hold up to salt. But if I wanted to experiment with it, I would
>certainly start by building the basic wall with the Thermal Ceramics brand
>K23 brick. (A warning: B&W used to make higher grades bricks too, and I
>suspect that Thermal Ceramics still does. BUT only their K23's did well in
>salt.)
>
>As a gross generalization, I have found that high-alumina formula products
>which are formulated to "resist" salt have not stood up well during repeated
>firings. Over the years, I have tried special shelves and a variety of kiln
>furniture. What generally seems to happen is that the surface resists salt
>nicely, but the interior binders break down over time. So the products
>remained beautifully clean on the surface, but lost their structural
>strength. (I m just guessing that it was the binders that broke down -- I
>can only tell you for sure that they got soft and crumbly.) I have tried
>several high-alumina castables inside salt kilns, some commercially
>available, some homemade. They reacted the same way the shelves did -- e.g.,
>they resisted salting and stayed clean-looking; but they lost their
>structural integrity. In fact, the castables all expanded over repeated
>saltings. The fireboxes and bottom of my first kiln expanded so much they
>bent the iron corner-bracing and eventually pushed out so far that I had to
>take the kiln down. These days, I stick with high-quality hard brick for
>anything structural in my kilns. But when I was recently resurrecting my
>old salt kiln, I did buy some beautiful new Thermal Ceramics K-23's for the
>door. I'm still enjoying the luxury of bricking up the door with so many
>unbroken bricks!
>
>Hope this helps!
>
>Nan Rothwell
>In Nelson County, Virginia where it is 18 degrees and windy...
>
>I have heard rumors of a sucessful salt kiln built of IFB's (soft brick)
either at Penland or Arrowmont or Appalachian Center for Crafts that had its
interior coated with zirconium.Rumors are rumors but may be worth investigating.
LYN PEELLE on sat 28 dec 96
Does anyone outhere do anything with Low fire salt
firings? I have an old elec. kiln I would like to use for
this end and any adivse would be greatly appreciated!
H N Y
Lyn
Vince Pitelka on thu 2 jan 97
>>I have heard rumors of a sucessful salt kiln built of IFB's (soft brick)
>either at Penland or Arrowmont or Appalachian Center for Crafts that had its
>interior coated with zirconium.Rumors are rumors but may be worth
investigating.
Brooks -
Our salt kiln is hardbrick, but it has a hinged softbrick door (single 4
1/2" thickness in a steel frame). It has been used heavily for at least
five years, and has held up extraordinarily well. I do not know what the
original coating was, but since I arrived here we have simply coated it
periodically with a salt-kiln-wash - 60% alumina hydrate, 30% kaolin, 10%
ball clay. We are finally experiencing some breakdown on the hotface of the
IFB, and have been repairing the surface with APGreen Greenpatch-421. I
expect that soon we will have to completely re-do the door, so I am very
interested in this line of discussion.
In this particular door design, the bricks are dry-stacked in the heavy
angle-iron door frame, with space left down one side and across the top. A
piece of steel flat-bar is slipped into this space, and bolts are screwed
into nuts welded onto holes in the top and side of the outer frame, so that
as the bolts are screwed in they press the flat-bar against the softbrick,
firmly clamping the whole assembly in place. This has worked extremely well
with no adjustments in the tension over the years.
- Vince
Vince Pitelka - vpitelka@Dekalb.Net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts, Smithville TN 37166
mel jacobson on thu 9 jan 97
we have a soft brick salt kiln at the farm... the inside looks like hell, a
lot of surface melting, peeling, repaired areas, sprayed stuff, salt on
everything and it works like a dream.. it is a 25 cu ft. flat top...free
stack door of k-26's.
we have fired it many times and of course some of the surfaces of the k-26's
melt, but with some repair at the end of the flame way and some hard brick
deflectors it does work, is very fast (6 hours to cone 10) and is classic
salt. but do not expect softbrick to hold up to salt...it does not... but it
does sort of self seal, then peel, but it will take many firings before we
have to replace any brick. and if i had to build another one i would do it.
compared to the firing time of an equal hardbrick kiln this one is
perfect. i would do more spraying of coatings for they do work... it is
the future for all kilns in my opinion. for what it is worth. mel
jacobson/minnesota
NU POTTERY on sun 18 jan 98
The question was asked about soft brick and salt kilns. I built my salt
kiln in 1993. I ended up using hard brick on the inside walls, soft brick on
the outside and a soft brick arch and door. I Fire about once a month. I had
been putting a high alumina wash on the interior hard brick but I was
experiencing deterioration on the walls of hard brick and around the fire box.
Last year I coated with ITC. This seems to have stopped the deterioration. I
have replaced about 6 or 7 softbrick in the arch, and one in the door. My door
goes completely across the front of my kiln, so there is a lot of soft brick
being exposed to the salt. I should mention that this is a 40 cubic foot
kiln. My experience has been, that there is little or no salt build up on the
softbrick arch or door, but I used some bricks that were given to me, they
were K23's made by Kaiser, no longer available. Nothing wants to stick to
them not even ITC. I had put a kiln wash on the door but nothing on the arch.
I won't hesitate to use soft brick throughout the next time I build.
Having fired salt kilns made of all hard brick before, the savings in
fuel, firing time, ease of firing and ease of building should encourage you to
give it a try.
Nancy Utterback
Fay & Ralph Loewenthal on fri 17 jul 98
Jack salt vapour rusts away anything and everything. It
sounds as if there is plenty of that coming out of the salt
kiln. We moved to the coast 3.5 years ago. In that time my
Volkswagen Mikrobus has almost rusted away in parts. I
was told to have it treated when I came down here, but due
to lack of funds and memory it was not done. Hope this
answers your question Ralph in PE SA
William on fri 19 apr 02
I am looking for a salt kiln in the Atlanta area that I can help fire in
exchange for kiln space. Any help would be very much appriciated.
Ben Morrison on mon 23 apr 12
Has anyone ever used SiC bricks for a salt or wood kiln? The SiC shelves st=
=3D
and up well for me so I figured it would stand to reason the SiC bricks wou=
=3D
ld as well. =3D0A=3D0A=3D0A-Ben=3D0A=3D0A=3D0A=3D0A________________________=
________=3D0A Fr=3D
om: mel jacobson =3D0ATo: Clayart@LSV.CERAMICS.ORG =3D0A=
Sent=3D
: Monday, April 23, 2012 5:15 PM=3D0ASubject: salt kilns=3D0A =3D0Awe are b=
uildin=3D
g a new one at our farm.=3D0Ai am taking vince's advice and building it=3D0=
Aent=3D
irely of hard brick...sealed as tight as we=3D0Acan get it.=3D0A=3D0Athis s=
hould =3D
be the last salt kiln we ever build.=3D0Ait should last a long time.=3D0A=
=3D0Ai m=3D
ade a huge mistake in my post to clayart=3D0Aabout salt kilns.....i was mak=
in=3D
g reference to=3D0Asoftbrick coated kilns, partial hard brick, fiber=3D0Aet=
c.=3D
=3D0Anone of them ever totally worked for us.=3D0Athey got longer life with=
itc=3D
coatings, but=3D0Anot fool proof.=3D0A=3D0Ahard brick is the only kiln tha=
t will=3D
hold up to=3D0Asalt.=3DA0 (i still do not love salt.)=3D0Ai glaze all my p=
ots th=3D
at go into salt...just a=3D0Apreference.=3DA0 it does not mean good or bad.=
=3DA0 =3D
just=3D0Aan aesthetic feeling.=3D0Athanks vince.=3D0Amel=3D0Afrom: minneton=
ka, mn=3D
=3D0Awebsite: http://www.visi.com/~melpots/=3D0Aclayart link:=3DA0 http://w=
ww.vis=3D
i.com/~melpots/clayart.html
mel jacobson on mon 23 apr 12
one thing i know for sure.
salt kills kilns.
if you fire with salt:
it takes a long time to load.
the shelves go to hell.
the posts go to hell.
the kiln crumbles.
and, i don't know if the
salt glaze is that great.
(my opinion.)
it is a good learning experience.
and, you will have to throw away
the kiln after about 30-50 firings.
shino glaze makes the inside of the kiln pretty.
what else it does?....i don't know.
we just had an old bucket around, and sprayed
it in.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
Vince Pitelka on mon 23 apr 12
mel jacobson wrote:
"salt kills kilns. if you fire with salt it takes a long time to load, the
shelves go to hell, the posts go to hell, the kiln crumbles, and, i don't
know if the salt glaze is that great. (my opinion.) it is a good learning
experience, and, you will have to throw away the kiln after about 30-50
firings. shino glaze makes the inside of the kiln pretty. what else it
does?....i don't know. we just had an old bucket around, and sprayed it in.=
"
Hi Mel -
Having used salt kilns back in Humboldt County quite a bit, and having used
salt kilns continuously at the Craft Center for the past 18 years I'd like
to comment on the above. It is appropriate to say that salt and soda
corrode kilns and refractory, but ultimately every kind of firing kill
kilns. Salt-fired ware can be exquisite, depending on the design and
craftsmanship of the ware, the glazes and slips used, etc., just as with an=
y
other firing process.
Except for that one salt kiln I mentioned that was constructed from
high-alumina Kruzite hardbrick, we get at least 300 firings out of our
high-duty hardbrick salt kilns. I have not kept exact track of the exact
number of firings, but the one we tore down last spring lasted ten years in
institutional use. We use cut firebrick pieces as kiln furniture in our
salt, soda, and wood kilns, and they last almost indefinitely. Silicon
carbide shelves also last almost indefinitely. The thinner nitride-bonded
shelves don't hold up quite as well, especially when a student knocks a
stack of them over - oh that hurt!
The shino glaze helps to seal the porous surface of the brick more quickly,
decreasing the amount of sodium vapor penetrating the brick and perhaps
postponing breakdown a little longer. It's probably a more important
technique to use on soda kiln, because salt kilns generally develop a shiny=
,
smooth glaze on the inside fairly quickly while soda kilns do not.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
mel jacobson on mon 23 apr 12
we are building a new one at our farm.
i am taking vince's advice and building it
entirely of hard brick...sealed as tight as we
can get it.
this should be the last salt kiln we ever build.
it should last a long time.
i made a huge mistake in my post to clayart
about salt kilns.....i was making reference to
softbrick coated kilns, partial hard brick, fiber
etc.
none of them ever totally worked for us.
they got longer life with itc coatings, but
not fool proof.
hard brick is the only kiln that will hold up to
salt. (i still do not love salt.)
i glaze all my pots that go into salt...just a
preference. it does not mean good or bad. just
an aesthetic feeling.
thanks vince.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
jonathan byler on mon 23 apr 12
To anyone building don't forget to leave expansion joints! I made
ours all pretty looking and well put together, but without the
expansion joints.. now is a bit bloated at times. still, fires well
enough, and doesn't take days to get to temperature, but not near as
pretty as it was when I built it. I am not making that mistake with
our wood kiln. You might try laying the hardbricks up on their sides,
that would surely reduce the thermal mass in the kiln that needed to
be heated. I heard of someone doing this, but hadn't seen the results
yet.
On Apr 23, 2012, at 7:15 PM, mel jacobson wrote:
> we are building a new one at our farm.
> i am taking vince's advice and building it
> entirely of hard brick...sealed as tight as we
> can get it.
Edouard Bastarache on tue 24 apr 12
Why not use boron nitride bricks
Plejkore,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://smart2000.pagesperso-orange.fr/bloggs_edouard.htm
http://www.facebook.com/edouard.bastarache
----- Original Message -----
From: "Ben Morrison"
To:
Sent: Tuesday, April 24, 2012 1:09 AM
Subject: Re: salt kilns
Has anyone ever used SiC bricks for a salt or wood kiln? The SiC shelves
stand up well for me so I figured it would stand to reason the SiC bricks
would as well.
-Ben
________________________________
From: mel jacobson
To: Clayart@LSV.CERAMICS.ORG
Sent: Monday, April 23, 2012 5:15 PM
Subject: salt kilns
we are building a new one at our farm.
i am taking vince's advice and building it
entirely of hard brick...sealed as tight as we
can get it.
this should be the last salt kiln we ever build.
it should last a long time.
i made a huge mistake in my post to clayart
about salt kilns.....i was making reference to
softbrick coated kilns, partial hard brick, fiber
etc.
none of them ever totally worked for us.
they got longer life with itc coatings, but
not fool proof.
hard brick is the only kiln that will hold up to
salt. (i still do not love salt.)
i glaze all my pots that go into salt...just a
preference. it does not mean good or bad. just
an aesthetic feeling.
thanks vince.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
jonathan byler on tue 24 apr 12
why not just use high duty hard bricks? they work just fine. the
only reason I would look for something else is if it transfered less
heat, and had a lower coefficient of expansion. like IFB's. But
experience says it is a bit of a fools errand to use them, though
some find it cost effective.
On Apr 24, 2012, at 9:56 AM, Edouard Bastarache wrote:
> Why not use boron nitride bricks
>
> Plejkore,
>
> Edouard Bastarache
> Spertesperantisto
>
> Sorel-Tracy
> Quebec
>
>
>
>
> ----- Original Message -----
> From: "Ben Morrison"
> To:
> Sent: Tuesday, April 24, 2012 1:09 AM
> Subject: Re: salt kilns
>
>
> Has anyone ever used SiC bricks for a salt or wood kiln? The SiC
> shelves
> stand up well for me so I figured it would stand to reason the SiC
> bricks
> would as well.
>
>
> -Ben
>
>
>
> ________________________________
> From: mel jacobson
> To: Clayart@LSV.CERAMICS.ORG
> Sent: Monday, April 23, 2012 5:15 PM
> Subject: salt kilns
>
> we are building a new one at our farm.
> i am taking vince's advice and building it
> entirely of hard brick...sealed as tight as we
> can get it.
>
> this should be the last salt kiln we ever build.
> it should last a long time.
>
> i made a huge mistake in my post to clayart
> about salt kilns.....i was making reference to
> softbrick coated kilns, partial hard brick, fiber
> etc.
> none of them ever totally worked for us.
> they got longer life with itc coatings, but
> not fool proof.
>
> hard brick is the only kiln that will hold up to
> salt. (i still do not love salt.)
> i glaze all my pots that go into salt...just a
> preference. it does not mean good or bad. just
> an aesthetic feeling.
> thanks vince.
> mel
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
Vince Pitelka on tue 24 apr 12
Jonathan Byler wrote:
"To anyone building don't forget to leave expansion joints! I made ours al=
l
pretty looking and well put together, but without the expansion joints.. no=
w
is a bit bloated at times. still, fires well enough, and doesn't take days
to get to temperature, but not near as pretty as it was when I built it. I
am not making that mistake with our wood kiln. You might try laying the
hardbricks up on their sides, that would surely reduce the thermal mass in
the kiln that needed to be heated. I heard of someone doing this, but
hadn't seen the results yet."
Jonathan -
On the hotface layer I have never left expansion joints except at the very
ends of the rows where the joints are not exposed on the inside. On the
outside layer I use IFBs wherever I can - wherever they are not in contact
with a port or door jamb. So that accommodates expansion. If you leave
expansion joints exposed on the inside it just accelerates the deterioratio=
n
of the kiln, providing gaps for the soda to enter the kiln wall, which will
ultimately cause more expansion and deterioration of the kiln.
I am not sure what you mean by laying the hardbrick up on their side. Do
you mean so that your wall thickness is only 5"? I don't think you'd want
to do that with an all hardbrick kiln. And besides, for the header courses
you would have to trim the bricks down to 5" long which would leave you wit=
h
a lot of 4" pieces, and what would you do with them? I suppose you could
divide them again and use them for kiln furniture. But this sounds like a
lot of work, and you don't want to reduce the thermal mass if the kiln is
all hardbrick. You reduce the wall thickness to 5" of hardbrick and the
outside of the kiln is going to be so hot that you can't get near it.
When I referred to an all-hardbrick salt or soda kiln in an earlier post, I
meant all hardbrick on the hotface. As mentioned above, I use softbrick
wherever I can on the outside layer, and I use a thick layer of homemade
castable over the arch.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Vince Pitelka on tue 24 apr 12
Ben Morrison wrote:
"Has anyone ever used SiC bricks for a salt or wood kiln? The SiC shelves
stand up well for me so I figured it would stand to reason the SiC bricks
would as well."
Edouard Bastarache wrote:
"Why not use boron nitride bricks?"
I do not know of anyone who makes silicon carbide bricks, and if they did,
how would you afford them? Also, they would be so dense as to provide
almost no insulating value at all. A high-duty hardbrick is very porous in
comparison, and while porosity is problematic in salt and soda kilns, we ca=
n
afford to eliminate it from the bricks. Sealing the inside surface is abou=
t
the best we can do.
And regarding Edouard's question about boron nitride bricks, Edouard, are
you willing to pay for them? It is important to realize that buying bricks
that are far more expensive would be counter-productive. It isn't that muc=
h
trouble to rebuild a salt kiln every ten years, replacing the hotface
bricks.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Vince Pitelka on tue 24 apr 12
I wrote;
"A high-duty hardbrick is very porous in comparison, and while porosity is
problematic in salt and soda kilns, we can afford to eliminate it from the
bricks."
I meant to say "we CAN'T afford to eliminate it from the bricks."
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
jonathan byler on wed 25 apr 12
vince,
I had meant 2.5" (laid up on their side rather than standard 4.5"
laying flat) of hardbrick with a castable/ifb insulating layer on the
outside. I can't see building a high fire kiln with all hardbrick,
although people have often done it. seems a huge waste of resources,
especially to fire such a thing. as to expansion joints, that was
exactly what I was talking about.
>
>
jonathan byler on wed 25 apr 12
I think edouard was being sarcastic. he's famous for making jokes.
>
> And regarding Edouard's question about boron nitride bricks,
> Edouard, are
> you willing to pay for them? It is important to realize that buying
> bricks
> that are far more expensive would be counter-productive. It isn't
> that much
> trouble to rebuild a salt kiln every ten years, replacing the hotface
> bricks.
> - Vince
>
ivor and olive lewis on wed 25 apr 12
I fired with Sodium Chloride using SiC shelves and had some frothing in
areas not protected by kiln wash.
Remember fine Silicon carbide is used as an auto-reducing agent to obtain
copper reds.
I did glaze trials using slate grinding waste containing residue from the
grinding wheels which produced melts with significant frothing.
Silicon carbide is reputed to react with molten alkali salts, alkali
hydroxides and also with Carbon monoxide at salt and soda glazing
temperatures.
See L. A. Lay,"Corrosion resistance of technical ceramics" ISBN
0-11-480051-0., 1983
Ivor Lewis,
REDHILL,
South Australia
Edouard Bastarache on wed 25 apr 12
Hehehehehe Jonathan,
the idea comes from a chemical engineer who works for QIT Iron
and Titanium located here in Tracy.
With the cooperation of ACERS he designed this kind of bricks for QIT's
90-ton reduction kilns. The walls are 4 feet thick and these kilns do not
have shells.
In these kilns ilmenite is reduced to iron and titanium dioxide slags.
Plejkore,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://smart2000.pagesperso-orange.fr/bloggs_edouard.htm
http://www.facebook.com/edouard.bastarache
----- Original Message -----
From: "jonathan byler"
To:
Sent: Wednesday, April 25, 2012 1:22 AM
Subject: Re: salt kilns
>I think edouard was being sarcastic. he's famous for making jokes.
>
>>
>> And regarding Edouard's question about boron nitride bricks,
>> Edouard, are
>> you willing to pay for them? It is important to realize that buying
>> bricks
>> that are far more expensive would be counter-productive. It isn't
>> that much
>> trouble to rebuild a salt kiln every ten years, replacing the hotface
>> bricks.
>> - Vince
>>
>
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