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Bizen Clay Body?

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#1 Biglou13

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Posted 03 September 2013 - 02:49 PM

does any one have a recipe for a Bizen like clay body. 

 

found this but im told its close but no cigar

 

75 xx saggar

15 red art

10 custer


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#2 JBaymore

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Posted 03 September 2013 - 03:19 PM

The Bizen clay is a fine particled but silty clay dug from seams under the rice fields. High in iron content. Because it is silty (very fine but non-plastic content).... it is not as dense, greasy, and plastic as bodies we might compose here in the West using the commercially available beneficiated clays. It is highly contaminated with carbonaceous impurities. Some of it is almost black in the raw wet state.

High carbon ball clays will give you some of the carbonaceous material (which affects the way the clay fires as the high iron content gets some reduction to FeO very early)...... but will ALSO automatically add very fine highly plastic clay particles.

I had a pretty good recipe back when there were some raw materials that were available that are no longer with us. One used a lot of PBX fireclay (may it rest in peace).

Baymore's Bogus Bizen

PBX fireclay 52
NH red silty clay 16
Bandy Black ball clay 17
G-200 Feldspar 7.5
200m Flint 7.5
80m granite dust 1

PBX is a high iron but refractory clay. (Sewwt stuff) Bandy Black is a high carbon ball clay.

I stopped playing with this idea a long while back.... so haven't updated this at all.

Hopefully it is helpful to you as a starting point.

best,

.............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#3 MMB

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Posted 05 September 2013 - 10:34 PM

Wasnt off center talking about how strong XX Sagger and Red Art 50/50 makes an incredibly hard clay because how each reacts during firing? I remember the post and it caught my attention and seemed temping to test. Not to derail the topic of this thread, because I really would like to try something like the bizen body, but what is a good integrity test?

 

I know the whole drop bonedry clay with certain amounts of grog added test, but what about the fired body strength?

 

edit: I mean my local clay soil is iron rich, so couldnt you just use it along with other carbon rich inredients? and even if the iron levels are not right couldnt you just add to it? I added EPK to some soil I dug 7 feet down (I like to dig and I have a big pit) and strained through a silk screen silk to get out all the larger stuff and it feels like 80% a good clay.



#4 Biglou13

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Posted 06 September 2013 - 04:20 AM

De rail away...... Actually your not technically de railing since question is directly related. And I'm very interested in learning about formulating clay bodies.

Atomic axe. Gave me some valuable links regarding clay testing ill search for those.
http://digitalfire.c...bodies_211.html

The tests didn't adress body stregnth. They did adress shrinkage , absorption, slumping . But I m also interested in "body stregnth"
But from a scientific perspective what does that mean. I under stand there is a breaking test in ceramics where I think a known force is applied and break point is recorded. Not sure what that test is. I'd be more interested in a chip test that mimics the real world use of dinner ware. I also handsome people look at work and the were flicking it with their fingers to see how piece rang. Not,sure what that indicated.

But off center aka Jim is from lizella. South of you in lizella home of lizella clay. And he has made clays from it. From what John b. is listing I'm I'm considering the amount of Organic materials in clay. Which tend to make clay black. And I've seen local,clay here in Florida that us silty and highly organic/carbonaceous. Similar if not same as what indigenous people used. Too bad off center is no longer here, he was a wealth of knowledge an would be familiar with Georgia clay.

To add to the confusion. I've seen different versions of bizen clay.....some that finish lighter, and flash when fired with organic material, and a darker earthier colored body. I've also read we're bizen kiln temps are lower. But longer firing times produce the melt... I have feeling the c
Recipe John b. gave is the darker.

Have you fired your home made clay. Have you added anything else to it other than epk? I have a feeling the epk will need some flux.
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#5 JBaymore

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Posted 06 September 2013 - 09:57 AM

Lou,

There are lot of tests for "body strength". ASTM lists a lot of the most common...... but you have to pay to get copies of the actual procerdures that ASTM oversees.

Modulus of Rupture (MOR) is the one that I think you are refering to above. A 1 cm x 1 cm machined bar of the body is suspended between two knife edge supports 10 cm apart. Force is applied to the center point between the supports on a knife edge contact point... and than the result is measured when it ruptures. It measures just one aspect of the possible ways a body can be "stressed". This test can be done in the dry green, bisquerd, or finish fired states.

best,

............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#6 JBaymore

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Posted 06 September 2013 - 10:10 AM

A lot of the "traditional" clays in use in Japan are, by today's modern industrial yardstick..... bad clays. Often THAT is exactly what gives them the character that we so enjoy. The same tends to be true of glazes........ good "well formulated" stable glazes often are bland in visual character....... but they don't leach, fit the body, don't abrade or mark, and so on.

Many of the traditional Japanese bodys are prone to dunting on kiln cooling, would not stand up to stuff like repeated oven or microwave use, leak or weep liquids, and are not very strong or are brittle. The tradition of using that particular clay developed because that was what was available to the potters in that geographical area (Japan is mountainous and in the old times travel was difficult), pots needed to be made, so they learned to use it.

One of the clays I use in Japan, for the larger pieces, if the pieces are not bathed for an hour or so in VERY hot water immediately after unloading the kiln.... they will crack. Happens 100% of the time like clockwork. You learn how to handle the body.....what it will do and what it won't.

Some of the clays I've used in Japan are horrible to work with.,... unless you use the techniques the way the locals have learned to work with them.

SO .... dig up that local "dirt", mix up some, and then start playing with it to learn "what it wants". Maybe you can only handbuild with it. Maybe you have to throw really wet. Maybe you have to throw really dry. Maybe you have to form it into blocks and carve it thin. Maybe you have to fire it to a low temperature over a LONG time. Maybe you have to cool it very fast. Maybe you have to cool in reduction.

What you may find is that you have something pretty unique when you get to the end of the discovery process.

best,

.............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#7 Biglou13

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Posted 06 September 2013 - 08:23 PM

Yeah what he said ^^^^
That's why I mess with making my own clay
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
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#8 MMB

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Posted 07 September 2013 - 09:48 AM

As always Baymore with a very informative addition to the topic. Always thankful for the time you take to write your indepth and lengthy posts. Clay bodies interest me so much and for a while , over a year ago, I got stuck with the "local clay" aspect and had lots of failure. I still dabble with it hoping to find that right blend, but not so much that the local clay takes the smaller percentage in the body. I also to learned that I was letting it take me away from everything else, so I put it on the back burner for those "off" kinda days. This thread sparked my interest and rekindled a little bit of that old habit.







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