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updated thu 20 jun 02


Siu-Bing McInnis on thu 19 dec 96

I just find a local clay product company who sale fireclay in powder form
for 4.00/50lb. I am looking for information on preparing the clay for both
sculpture and throwing use. Where do you buy sand to make with the clay and
how to do it. Thanks for the info in advance.

Wherever you go, there you are...

gshaffer on tue 2 sep 97

Hello clayarters at large,

Afeter many years of frustration with different fireclays and all
their different problems i thought i had found the solution by using 50
mesh hawthorne firecly, wrong, i just made my fall production for a
couple of shows from a new batch of hawthorne 50 mesh to find hundreds
of annoying speckles per square inch on every pot. Now as other potters
who do stoneware i like a few iron speckles just fine, but this is like
having the measles infect hundreds of pots and i am in dispair. Jonathan
Kaplan in his clay info on line does say to avoid fireclay like the
plague, but what do i replace it with in my body, i once used goldart
but it went to being too much sulfur, then pinelake and it dried up,
then hawthorne 35 mesh mesh and it had major pop offs recently from
lime, so last resort wash 50 mesh and now this. Can anyone help me?
Thanks gang. cone 9 reduction kinda guy i am i am

gary shaffer

Eleanora Eden on wed 3 sep 97

Hi Gary and all,

Here's the stoneware recipe I used to use:

Eden's c10 buff stoneware
#50 49'er ball clay
#50 redball
#50 Kaiser fireclay (up to #80)
5- 1qt saucepans each of
2 cups vinegar
1/3 garbage can slop
#36 water (that's two buckets)
#2 bentonite

I wrote Gary about fireclay and offered this recipe and thought what the
hell why not share it with the whole group.

This is as documented 20 years ago I do not have any more info than that so
maybe somebody else knows what redball is I don't. But I do remember
that I promised myself I wouldn't bother sharing recipes with clayart
anymore as the last time I shared this recipe a little storm of nastiness
started over what is a saucepan doing in a recipe.

So Gary I hope this helps. And for the rest please take it in the spirit
it is offered or ignore it.
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101

iandol on wed 22 may 02

There have been several references to this material over time which =
extol its virtues in adding tooth and promoting plasticity enabling the =
production of better thrown pots. Nothing wrong with that.
But I think it may be useful to suggest that all Fireclays may not =
conform to that ideal. You need to know more about the stuff you are =
getting. I suggest this simply because some fireclays are derived from =
Coal Measure Seat Earths which are Shales. So they are not always as =
plastic as might be desired and additions of Ball clay may be needed to =
improve the pasticci qualities.
A long time ago I used clay from a Salt Glaze Plant which seemed to be =
very plastic because it moulded up well and extruded with ease. But it =
was no use on the wheel because it contained too much none plastic =
A second important point is that they may contain high levels of free =
Silica. I have used what might be termed "Fireclay" which contained =
slivers of white quartz which had razor sharp edges. Throwing that stuff =
resulted in some nice brown stains when the pots were fired! As we well =
know, high levels of free silica can cause problems.
So, if you are intending using Fireclay to exploit its virtues, ask for =
the data sheets.
With best regards to all,
Ivor Lewis.

BVCuma on fri 14 jun 02

>>And you can design clay bodies that have no garbage like
fireclays, <<
.>> As the availability of "decent" fireclays such as GreenStripe, =
Lincoln, and Sutter have all but diminished<<

Hi Jonathan

As I use a relatively high percentage of fireclay in my body
I would like to hear what you further have to say in
regards to your definitions "garbage" and "decent".

Quality in product/materials in India is often at the lower end of the =
so habitually I suspect I may have somewhat less in my fireclay.

I do have a problem with "pulling" handles etc.
So plasticity is not at its optimum..
The clay does have a tendancy to crack.

I plan on trading off equal amounts of ball clay
for the fireclay till this bad habit is broken.

Again your comments would be appreciated


Jon Pacini on tue 18 jun 02

Greetings All-----There's been a thread going on about fireclay and I
thought I'd chime in with my 2 cents worth---
There are things you can expect from fireclays and some things you
Fireclays bring some very good attributes to the party. Color, texture
and throw ability are some of the good things. California Fireclays have
fine particle sizes and are extremely plastic, Missouri fireclays tend to be
courser and add "tooth" to a body. There are gold fireclays and orange ones
and speckled ones. Most stonewares after all are based on fireclay.
Back in the 1940's, before there were commercially pugged clays
available in Southern California, potters here or elsewhere for that matter,
could go to a building supply yard and get fireclays,(because they were and
are used as an additive to mortar and stucco), add a little ball clay, maybe
some sand, sometimes some spar or red clay and they could develop a whole
stable of serviceable ^10 stonewares.

Each fireclay is quite unique in character, but what they all have in
common is that refractory firebrick can be made out of them. That's
primarily why they are mined. They are also used extensively in mortars,
stuccos and pond liner. Down at the bottom of the use list, at least in the
amount used, is pottery. Which is where we potters reside with nearly all of
the minerals we use.

Some potters have had extremely bad experiences with fireclays. Well, in
the years I have been involved with pottery and clay making, I've seen just
about every single mineral we potters use cause some extremely bad
experiences. Not to make light of those experiences, but it does seem come
with the territory.
Now it's a good thing to minimize the chances of having a bad
experience, but I don't see how staying away from fireclays in general is
going to accomplish that. You might just as well stay away from ballclay and
kaolin too, they are all subject to their own variations and contaminations
in mining and processing. You just trade one set of things that can go wrong
for another.

If you use a fireclay based clay body, some time in your pottery
lifetime you could experience one or all of the most common difficulties:

1 course material in the fireclay. This is commonly, a: unground clay b:
sand c: gypsum d: lignite

2 excessive out-gassing. This difficulty is most often caused by, a:
sulfates b: carbonates

3 variations in color, raw and fired. This can usually be attributed to
variations in the composition of or % content of a: organics b: iron

All of these things can cause you grief if you don't know how to handle
them or are unaware that they can even occur. Learning to deal with the
limitations and variations of the materials as well as the possibilities and
advantages is part of being a craftsman. Know your materials, don't be
afraid of them.

When the guru's tell you to test-test-test, there's good reason.

Jon Pacini
Clay Manager
Laguna Clay Co

Where it's sooo hot and smoggy that I wish I were in Steamboat!!