Brad Sondahl on sat 23 oct 99
I've searched the archives, and the net, and found no description of
what firebrick are made from (or process). I assume hard bricks are
from fireclay and grog, but am curious about the composition of
insulating firebrick. I assume some fine particles are mixed in which
burn out to give the airspace, and from the fine texture guess the
material must be mostly kaolin. Anyone visited a firebrick factory?
--
Brad Sondahl
http://www.camasnet.com/~asondahl/bradindex.html
Sondahl homepage http://www.camasnet.com/~asondahl
Original literature, music, pottery, and art
Janet Kaiser on sun 24 oct 99
Brad,
I imagine Nikom & Co. will be able to give you all the information you need
on this. But to start you off this is from my 20+ year old notes! Do not
know how much is still current practice, but here goes:
BRICKS FOR KILN BUILDING:
Three main types are easily recognisable.
1. open-textured red clay building bricks.
2. hard, heavy refractory bricks
3. lightweight insulating bricks.
1. (will miss out this bit)
2. REFRACTORY BRICKS:
These are the hard, heavy, close-grained refractory bricks, generally made
from fireclay and grog and used for kiln-building (not to be confused with
the light insulating bricks). Industrial firebricks are given P.C.E. ratings
which refer to the deformation point/temperature. In England the grading is
according to alumina content. Those with more than 38% alumina are called
aluminous fireclay refractories (1650-1750 degrees Celsius).
In America ratings are:
1. super duty - 33.0 (working temperatures up to 1550 Celsius)
2. high duty - 31.5 (recommended for potters' kilns)
3. medium heat duty - 29.0
4. low duty heat - 15.0 (soften at 1400 Celsius and must be used well
below!)
Super quality firebricks are made from soaked refractory minerals producing
mulite and silliminite in the body.
FIRECLAY is a general name for sedimentary clays usually associated with
coal measures - they are ancient deposits. Many are black and shaly,
compressed to coal-like consistency and must be pulverised before use.
Impurities (minerals or oxides other than kaolinte, alumina and silicia)
should not exceed 5% in the best fireclays. Not all fireclays are
refractory. Some may contain carbonates of iron and calcium. Particle size
averages 0.1 to 5.0 microns. Reasonable plasticity and dry strength. Fired
colour is buff to light brown. Used by potters in refractory mixtures and as
a body component. Grading of refractory clays is by alumina content and when
38% or more known as aluminous fireclays. Fireclays commonly have 35-37%
alumina, although high-duty clays 45% or more.
Rich glaze quality and colour in celadons and other reduced iron glazes is
reputed to derive fro mthe use of fireclay in bodies. This is also known as
"sweated colour". Fool's Gold / Pyrites in fireclays also add interest.
Marl is also a low grade fireclay. Not used as much because of impurities.
3. INSULATING BRICKS
These are easily abraded, very porous, light in weight and superb at their
job. They are made in many qualities and degrees of heat resistance. Those
made from diatomaceous earth and either quarried and cut to shape or fired
into blocks with a little clay are weak in structure and are quite fusible.
The more refractory types are made from very pure and iron-free ceramic
materials and have an open, sponge-like appearance achieved by physical
means (e.g. mixing sawdust in the raw material) or chemical processes. These
are graded by a K factor. The number denoting the degrees Fahrenheit e.g.
K26 = 2600 deg F (1430 deg C) The higher numbers are stronger but marginally
less effective as insulators. They are also more expensive than firebricks.
++++++++++++++++++++++++++++++++
As for the process... I have no idea! I obviously thought it either not
worth noting or it was a "state secret" at the manufacturers... Sorry but it
is too long ago to even TRY to remember!!
Hope this helps anyway?
Janet Kaiser waiting for hurricane Irene to sweep up from France, whilst
making marrow chutney and getting my daily clay art fix...
The Chapel of Art: Home of The International Potters' Path
Criccieth, GB-Wales, UK
http://www.the-coa.org.uk
postbox@the-coa.org.uk
-----Original Message-----
From: Brad Sondahl
To: CLAYART@LSV.UKY.EDU
Date: 23 October 1999 21:05
Subject: Composition of firebricks
>----------------------------Original message----------------------------
>I've searched the archives, and the net, and found no description of
>what firebrick are made from (or process). I assume hard bricks are
>from fireclay and grog, but am curious about the composition of
>insulating firebrick. I assume some fine particles are mixed in which
>burn out to give the airspace, and from the fine texture guess the
>material must be mostly kaolin. Anyone visited a firebrick factory?
>
>--
>Brad Sondahl
>http://www.camasnet.com/~asondahl/bradindex.html
>Sondahl homepage http://www.camasnet.com/~asondahl
>Original literature, music, pottery, and art
>
Jerry Crimmins on sun 24 oct 99
In a message dated 10/23/99 1:06:04 PM Pacific Daylight Time,
bsondahl@camasnet.com writes:
<< ---------------------------Original message----------------------------
I've searched the archives, and the net, and found no description of
what firebrick are made from (or process). I assume hard bricks are
from fireclay and grog, but am curious about the composition of
insulating firebrick. I assume some fine particles are mixed in which
burn out to give the airspace, and from the fine texture guess the
material must be mostly kaolin. Anyone visited a firebrick factory?
>>
Hi
Macmillan Publishing carries Contemporary Ceramic Formulas by John W. Conrad.
It has formulas for fire brick, in fact the entire second chapter in the 1980
edition is dedicated to making molds and clay for both hard and soft brick,
Formulas for castable fire clay, kiln shelves and posts, kiln repair pastes
and so forth and on and on... I recommend Conrad's books he has something to
say about everything.
Otter
chris@euclids.com on sun 24 oct 99
> I've searched the archives, and the net, and found no description of
> what firebrick > Brad Sondahl
Hi Brad,
Try Thermal ceramics at http://www.thermalceramics.com/products.htm
Understandably, there are no specifics on the site but you can fill in a
literature request form at http://www.thermalceramics.com/literatu.htm
Failing that, if you send me a fax # i will have some info faxed to you.
chris
chris@euclids.com
www.euclids.com
800-296-5456
Anne POSSOZ on mon 25 oct 99
------------------
=3E ----------------------------Original message----------------------------
=3E =3E I've searched the archives, and the net, and found no description of
=3E =3E what firebrick =3E Brad Sondahl
=3E
=3E Hi Brad,
=3E Try Thermal ceramics at http://www.thermalceramics.com/products.htm
=3E Understandably, there are no specifics on the site but you can fill in a
=3E literature request form at http://www.thermalceramics.com/literatu.htm
I had a different bookmark:
http://www.thermalceramics.thomasregister.com/olc/thermalceramics/kspec.htm
Looks as the same location but apparently totaly different web server.
I can't find any data at http://www.thermalceramics.com
while at http://www.thermalceramics.thomasregister.com you get physical
properties, even in european units (althou sometimes not
completely converted).
Thanks to Janet for her clean explanation.
--
Anne Possoz Service Informatique Central Tel : (41/21) 693.22.49
Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)
Vera Rankovic on wed 27 oct 99
The subject rings a bell and I wouldn't bet my life on it, but I seem to
remember reading somewhere that the key factor in firebricks is air. Air is
the main insulator, as in every insulation treatment. To get air into the
brick, I think one uses simple meth od of mixing clay with sawdust (the
fine particles that burn out) I don't remember the ratio. But it makes
sense. I seem to remember reading that - probably had to do with old Chinese
kilns - making firebricks was a relatively simple task.
Of course, shelves and furniture are quite another story.
Vera Rankovic
----- Original Message -----
From: Jerry Crimmins
To:
Sent: Monday, October 25, 1999 01:51
Subject: Re: Composition of firebricks
> ----------------------------Original message----------------------------
> In a message dated 10/23/99 1:06:04 PM Pacific Daylight Time,
> bsondahl@camasnet.com writes:
>
> << ---------------------------Original message----------------------------
> I've searched the archives, and the net, and found no description of
> what firebrick are made from (or process). I assume hard bricks are
> from fireclay and grog, but am curious about the composition of
> insulating firebrick. I assume some fine particles are mixed in which
> burn out to give the airspace, and from the fine texture guess the
> material must be mostly kaolin. Anyone visited a firebrick factory?
> >>
> Hi
>
> Macmillan Publishing carries Contemporary Ceramic Formulas by John W.
Conrad.
> It has formulas for fire brick, in fact the entire second chapter in the
1980
> edition is dedicated to making molds and clay for both hard and soft
brick,
> Formulas for castable fire clay, kiln shelves and posts, kiln repair
pastes
> and so forth and on and on... I recommend Conrad's books he has something
to
> say about everything.
>
> Otter
| |
|
