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originally made by Babcock and Wilcox.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.
| |
|
