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Biglou13

Making clay 101

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Min    783

min yes please chare recipes either here or pm.

 

 

Campana Midrange Porcelain Cone 5-8

 25 Grolleg

10 C&C Ball Clay

 10 Tile #6 Kaolin

 35 Minspar

 20 Silica 325 Mesh

 2.5 Bentonite L-10 White

 

I messed around with this and subbed in some 3110 for part of the flux, my version of his clay is:

22  Grolleg

9  C&C Ball Clay

14  Tile 6

32  Minspar

20  Silica 200 mesh

5  Ferro 3110 

3 Bentonite, white

 

Galloway Porcelain Cone 6

35  EPK

15  Tile 6

5  Sagger XX Ball Clay

23  Nepsy

22  Silica

3  Bentonite, white

 

The Campana ones are nice and white, throw pretty well but are expensive to make up because of the grolleg. I found the Galloway one throws better, handles etc have less cracking but it’s cream not white. When I went to school I was taught that porcelains don’t contain ball clay, so if these can be called porcelains is open to interpretation. I know most ^10 potters will say there is no such thing as a ^6 porcelain anyway  ^_^

 

Your Slightly Modified Lehman D12 looks quite close to the Galloway one. 

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Biglou13    202

I like the Galloway recipe

 

I live near the epk mine and is inexpensive. ( relatively). However the 12D is technically a cone 10 and up clay for woodfire. It super flashy in wood fire, broken pieces reveal a "bluish" body.

 

But yes I also fire some of the pieces electric.

 

I'm runniing formal tests now, Shrinkage, and vitrification/absorption

 

But from the recipes and from what I've read. I've seen similar bodies go from 3% (Ish) @cone 6 to .5% at cone 10.. The vitrification rate across temperature ranges is much narrower than other types of clay.

 

Non scientific testing indicates the the clay works at cone 6. I drink out of one every day.

 

I also made (recently) a 12d* that ads 36.8 ap green fire clay to 12d I replaced ap green with Hawthorne bond and it improved the clays working characteristics. Throwing feel drying, it's not as finicky.

 

I like the Galloway recipe with addition of saggar xx. Probably improves throwing charteristics. And saggar xx is proven performer in woodfire. I'll bet that Galloway recipe would hold up and be beautiful in wood fire.

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neilestrick    1,381

 

neil:

http://www.anagama-w...clay_bodies.php

 

Slightly Modified Lehman D12

EPK 36.80

Nepheline Syenite 24.50

OM4 Ball Clay14.30

Silica19.10

Bentonite5.10

Redart2.50

Sum102.30

This slightly Modified Lehman 12-D is derived from the recipie contained in Dick Lehman's article A New Approach To Long-Fire Results

 
i lowered the bentonite with slurry method clay was too buttery.
 
min yes please chare recipes either here or pm.

 

 

What you've got there is what I would call a domestic porcelain with some Redart added for color. And like I suspected, it's quite low in clay. Plus the clays that are in it are very fine grained, especially the ball clay and bentonite, both of which have high drying shrinkage rates. So I'm not surprised that it's finicky and prone to cracking. I'm also not sure why it needs that much Bentonite when it's got 14% ball clay in it. I would start reducing the Bentonite and see if the cracking issues improve. As you mentioned, adding fire clay will make it much more workable, as it improves the particle size distribution. I would replace the ball clay with fireclay.

 

Another really nice cone 10 body you may want to try is and equal parts body, 20% each fireclay, kaolin, ball clay, feldspar and flint. You could add a little Redart for color.

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Biglou13    202

I would recommend letting your dry mix slake in the wet mix at least overnight before you pour it into pillow cases. The lumps all be less pronounced.Marcia

I have two buckets of recovery/ new clay mix. Slaking as we speak. Thanks

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Biglou13    202

Neil are you suggesting replacing all or part of ball clay.

 

"A popular buff firing plastic Missouri fireclay of fine particle size. It fires a light color with approximately 10% shrinkage at cone 10. Ground to 35"-- digital fire.com

 

I think I have Hawthorne 40 mesh. Which would be even smaller particle size. Nonetheless it feels better. Yet to se how it performs under wood fire. But I trust the source dick lehman.

 

I do have some sagger xx. Not sure on particle size. S Would this work as well and it's known to flash well.

 

Never considere particle size in formulating clays? Is it better to include wide range of particle sizes?

 

What is your concern with silca in body?

 

When you say flint I assume that is silica?

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JBaymore    1,432

That much bentonite is very high. Likely drop the bentonite and shift the parts to the ball clay.

 

best,

 

....................john

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I am a little confused on all these clay recipes. Where is the locally dug clay that you are adding?

 

I noticed a few pages back there was some conversation on silica in clay. I found this a good read http://studiopotter.org/pdfs/sp28_1_sohngen.pdf maybe it can help you a little.

 

Enjoying the thread

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neilestrick    1,381

Neil are you suggesting replacing all or part of ball clay.

 

"A popular buff firing plastic Missouri fireclay of fine particle size. It fires a light color with approximately 10% shrinkage at cone 10. Ground to 35"-- digital fire.com

 

I think I have Hawthorne 40 mesh. Which would be even smaller particle size. Nonetheless it feels better. Yet to se how it performs under wood fire. But I trust the source dick lehman.

 

I do have some sagger xx. Not sure on particle size. S Would this work as well and it's known to flash well.

 

Never considere particle size in formulating clays? Is it better to include wide range of particle sizes?

 

What is your concern with silca in body?

 

When you say flint I assume that is silica?

 

Good particle size distribution gives you more workable clay. Large particles with smaller particles in between them, and even smaller particles in between those, etc, and a thin coating of water around everything. Everything sticks together very well.

 

No concern about the silica (flint) in the body. When you originally said that it had 25% neph sye, then I assumed it also had about that much silica for it to act on, which meant the clay content would be low, like a porcelain body.

 

I love fireclay, much more than ball clay. I'm not saying you necessarily need to replace the ball clay, but if you put in some fireclay, something else needs to come out. You could just add in 15% fireclay and take half from the ball clay and half from the kaolin. It would probably be a pretty nice body then. Hawthorne is nice stuff. All fireclays are in my opinion! They all feel a little different from each other, though, and some give larger iron spots than others.

 

XX Sagger is used a lot in white stoneware bodies if I remember right, since it's lighter in color in it's raw form than other ball clays,and for some reason everyone wants their white stoneware bodies to be white before they're fired, too. From a plasticity standpoint, my favorite ball clay is C&C from HC Spinks. I don't think that at 14% you're going to see a big difference in fired color  from one ball clay to another, but you might notice it in the throwing.

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Biglou13    202

That much bentonite is very high. Likely drop the bentonite and shift the parts to the ball clay.

 

best,

 

....................john

In my changes I've cut bentonite by 50%

Switched from red art to lizella.

First batch and all batches were slurry mixed. First batch was oddly sticky, rubbery and gummy. Dropping bentonite level helped a lot. I ended up groging up the first batch.

I think dropping half bentonite may not be enough.

Btw I blunged the bentonite prior to mixing clay.

 

Thank you sir for all your guidance and help

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Biglou13    202

I am a little confused on all these clay recipes. Where is the locally dug clay that you are adding?

 

I noticed a few pages back there was some conversation on silica in clay. I found this a good read http://studiopotter.org/pdfs/sp28_1_sohngen.pdf maybe it can help you a little.

 

Enjoying the thread

I'm not digging any clay. Too much work. Edgar plastic kaolin aka. EPK is less than one hour from where I live. I consider it locally sourced.

 

There was talk of digging, and indigenous people in this area made pottery. But finding and collecting, didn't work out.

 

Thanks for the links

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Biglou13    202

 

Neil are you suggesting replacing all or part of ball clay.

"A popular buff firing plastic Missouri fireclay of fine particle size. It fires a light color with approximately 10% shrinkage at cone 10. Ground to 35"-- digital fire.com

I think I have Hawthorne 40 mesh. Which would be even smaller particle size. Nonetheless it feels better. Yet to se how it performs under wood fire. But I trust the source dick lehman.

I do have some sagger xx. Not sure on particle size. S Would this work as well and it's known to flash well.

Never considere particle size in formulating clays? Is it better to include wide range of particle sizes?

What is your concern with silca in body?

When you say flint I assume that is silica?

 

Good particle size distribution gives you more workable clay. Large particles with smaller particles in between them, and even smaller particles in between those, etc, and a thin coating of water around everything. Everything sticks together very well.

 

No concern about the silica (flint) in the body. When you originally said that it had 25% neph sye, then I assumed it also had about that much silica for it to act on, which meant the clay content would be low, like a porcelain body.

 

I love fireclay, much more than ball clay. I'm not saying you necessarily need to replace the ball clay, but if you put in some fireclay, something else needs to come out. You could just add in 15% fireclay and take half from the ball clay and half from the kaolin. It would probably be a pretty nice body then. Hawthorne is nice stuff. All fireclays are in my opinion! They all feel a little different from each other, though, and some give larger iron spots than others.

 

XX Sagger is used a lot in white stoneware bodies if I remember right, since it's lighter in color in it's raw form than other ball clays,and for some reason everyone wants their white stoneware bodies to be white before they're fired, too. From a plasticity standpoint, my favorite ball clay is C&C from HC Spinks. I don't think that at 14% you're going to see a big difference in fired color from one ball clay to another, but you might notice it in the throwing.

I worked with the 12d* clay today. The one that adds fire clay (hawthorne) equivalent weight of epk. It has specks in it, which im assuming is iron spotting. I'll do more research on mixing up particle sizes of ingredients. I'm starting to undestand and like the qualities of fire clays, and saggar xx. Next mix I'll work them in.

I replaced percentage of the silica with silica of larger particle size, i will also revisit that on next mix.

 

Again thanks for all the help

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Biglou13    202

Porcelain musings

 

Much of the bodies I've been making have been epk based and porcelain -like

If you don't already know it's a dark grey clay in raw state, gray when wet, but very white when bone dry.

Fired it tends to off white maybe gray, but think its bit bluish.

It tends to be silty, thixotropic, prone to cracking, finicky to work with.

 

Well after along layoff from it in threw some helios by highwater today. What a treat! (@.90/pound it should be!)

 

What ingredients do you think are in helios or any other porcelain that make it a dream to work with.?

 

Cone 7-11 range is a plus.

 

Any one in your experiments come across a good good mix/formula/recipe

 

I don't necessarily need a white clay body. It would be nice.

 

I'm going to start incorporating like items multiple kaolins, different silica sizes, and multiple size particles when available.

Given its price I imagine it may use some of the more expensive kaolins.

 

Min .... Does the Galloway recipe feel like other commercial porcelains you have used?

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JBaymore    1,432

Don't put fine silica in clay bodies... that is for glaze use. Fine grinds promote cristobalite development.

 

best,

 

...................john

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Min    783

Min .... Does the Galloway recipe feel like other commercial porcelains you have used?

 

Thats a hard question to answer. It seems that the clay manufacturers have different definitions of what a porcelain is. The Galloway body throws well but is not translucent. I didn't find it any pickier with handles, warping or S cracks etc than the non translucent commercial bodies I have used. It is much easier to throw than the translucent english grolleg or New Zealand kaolin bodies I tried.The bowl below is Galloway (photo just taken on dining room table pls excuse the lighting).

post-747-0-49587400-1394249776_thumb.jpg

post-747-0-49587400-1394249776_thumb.jpg

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Biglou13    202

Don't put fine silica in clay bodies... that is for glaze use. Fine grinds promote cristobalite development.

 

best,

 

...................john

Dang already used it, been using it. Only been in 3 day firings, and cone 6 It's all the local supplier has, I can get 140 it's pretty much a fine sand. Should I just use the 140 sieve. I was worried it may be too large particle to melt in. If it will work it will help with particle size distribution.

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Biglou13    202

 

Min .... Does the Galloway recipe feel like other commercial porcelains you have used?

 

 

Thats a hard question to answer. It seems that the clay manufacturers have different definitions of what a porcelain is. The Galloway body throws well but is not translucent. I didn't find it any pickier with handles, warping or S cracks etc than the non translucent commercial bodies I have used. It is much easier to throw than the translucent english grolleg or New Zealand kaolin bodies I tried.The bowl below is Galloway, the lighting was dim, the bowl is actually whiter than shows in the pic.

Did you have to use low expansion clear?

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JBaymore    1,432

140m is "fine sand"??????  200m is total "powder".  Are you sure it is not mislabeled?

 

I can't believe that a ceramic supplier does not stock both 200 m (bodies) and 325 m (glazes).  Those are pretty much the "standard" situation in 100% of the suppliers I know.

 

best,

 

.......................john

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Min    783

 

 

Min .... Does the Galloway recipe feel like other commercial porcelains you have used?

 

Thats a hard question to answer. It seems that the clay manufacturers have different definitions of what a porcelain is. The Galloway body throws well but is not translucent. I didn't find it any pickier with handles, warping or S cracks etc than the non translucent commercial bodies I have used. It is much easier to throw than the translucent english grolleg or New Zealand kaolin bodies I tried.The bowl below is Galloway, the lighting was dim, the bowl is actually whiter than shows in the pic.

Did you have to use low expansion clear?

 

Yes.

The clear I use is: 

G1215U plus nepsy

Code Number:

 

Silica 26.00

EP Kaolin 14.00

Wollastonite 14.50

Minspar 24.00

Frit 3249 20.00

Nepheline Syenite 2.00

100.50

 

CaO 0.58*

MgO 0.24*

K2O 0.05*

Na2O 0.12*

P2O5 0.00*

TiO2 0.00

Al2O3 0.51

B2O3 0.33

SiO2 4.36

Fe2O3 0.00

 

You can easily tweek the expansion by increasing or decreasing the nepsy. One caveat with this (or any low expansion glaze), don't use it on the inside of a pot with with a high expansion on the outside, dunting / shivering risk. If you don't have Ferro 3249 then there are alternate recipes on the Digitalfire website. 

 

I used 200 mesh silica in the Galloway body.

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neilestrick    1,381

140m is "fine sand"??????  200m is total "powder".  Are you sure it is not mislabeled?

 

I can't believe that a ceramic supplier does not stock both 200 m (bodies) and 325 m (glazes).  Those are pretty much the "standard" situation in 100% of the suppliers I know.

 

best,

 

.......................john

 

 I've never even seen 140 mesh. That's really odd. I wonder if they're getting a super deal on it or something like that.

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JBaymore    1,432

 I've never even seen 140 mesh. That's really odd.

 

Me either.  Strange.

 

best,

 

......................john

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