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#21 Mark C.

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Posted 07 June 2013 - 01:51 AM

it can be.
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#22 Biglou13

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Posted 07 June 2013 - 03:33 PM

A lot of designing a clay body is making clay that matures and doesn't slump at the cone you want to use.

http://www.ceramicin...kage-absorption
http://digitalfire.c...bodies_211.html
http://digitalfire.c...t_bars_214.html

Those pages have info on testing the clays, what you want to do is limit shrinkage, while still providing a 'plastic' clay body that has strength and doesn't absorb liquids when high fired.

Ideal for you would be to try to design a versatile clay body that can get to cone 10 reduction no problem but functional at cone 6. also having your basic 4 ingredients in bag or half bag amounts in a batch would make it easier to make and produce without the pain of having bins to measure out single pound increments. sooooo ...

I would probably start with ...

lizella 25
epk 12.5
fire clay 25
neph sy 12.5
fine grog 12.5
flint 12.5

I would also try

lizella 37.5
feldspar 25
fireclay 12.5
epk 12.5
flint 12.5
fine grog ... maybe 5

From there you could probably hit it spot on ... but really it depends on your testing you do post ... so prepare for line blends to achieve what you want.

and ask offcenter also ... it's his part of the woods.

OH ... and if either of those pan out as is ... those clay bodies will be named "Funk Nasty Red: The Movie"


The more I learn about pottery the more I realize there is more i don' t know.

So thanks again to the learned ones for the info, and edumacation.

Let me just throw in I have spent some time researching making clay....not just waiting to be spoon fed


Some of my. Sources (second one a scholarly resource )

http://www.cheminfon...ceramics101.pdf
http://www.tulane.ed...ic%20terms.html
http://www.ceramicin...-your-clay-body



Lizella =earthenware clay

Epk= porcelain clay

Fire clay=
"Similar to stoneware clays, fire clays generally contain less flux (especially calcium and feldspar). Fired alone these clays won’t fully vitrify – even at high fire temperatures"

Neph Sy=can be used in a clay body when lowering the maturing temperature of the body is required....(flux, feldspathic)

Flint= " (the common name used in the industry for all forms of silica) serves as a filler, lending strength to the shaped body before and during firing"

Grog=opening material, structure, filler.......

Since lizella and epk were the givens. How and why did you select the other "ingredients"? And reasons behind proportions?

I vaguely understand some of choices but why fire clay, vs other clays?

And I'm not sure what Flint's role is here? glass former?

How would I make this body less red, more dirt ? How do I tweak formula to make epk. Dominant ingredient?

After reading yours and other posts. I realize you guys are to clay. Like a chef is to food. And say this to you as trained chef (previous career), I can tell you subtleties on braised short ribs.. Clay not so much....
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#23 Biglou13

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Posted 28 June 2013 - 09:13 PM

I'm getting closer to making my first batch of clay.

Silica (rose) by any other name would smell as sweet......

Silca, flint, silicon dioxide, quartz. Well it took me awhile but they are pretty much the same.

Silica come in many screen sizes, recipes often do not specify...

?what screen size should be used for clay, glaze?

In other threads there has been much talk about pugger ruining or changing the clay.

I'm planning in using the slurry method then drying on bed sheets, and hand wedge. No pugger (for now)

? Does the slurry method cause any issues as opposed to mixer method?.
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#24 Min

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Posted 28 June 2013 - 10:44 PM

I'm sure there are a lot of people who have mixed more clay than I have but for what it's worth - I have made Jeff Campagna's Porcelain, Val Cushings and Julia Galloways, in all 3 I used 200 mesh silica. All seemed fine to me, I don't know what a finer silica would do to a body.

The first few batches I mixed as a slurry, when I narrowed down which one I wanted to try a bigger batch of then I used my mixer/pugger. I dry mixed all ingredients (except macaloid) in a 50 gallon barrel in a large ball mill (without the porcelain marbles) then into the mixer/pugger. I have seen people mix the dry with an Odjob but they don't hold very much. (link http://www.leevalley...x?p=10338&cat=2,2180,33222) I let both the slurry mixed clay and the machine mixed clay sit for about a month before throwing. Slurry mixed was just as nice to throw as the other clay. The macaloid really helps with plasticity since I didn't let the clay age very long but it's pretty expensive.


There are several claybody recipes for low/med/high fire in Val Cushings handbook, it's interesting to compare the clay/flux ratios for the different ranges.


It was interesting to make clay and gave me a better understanding of the commercial bodies I use but it was too much work / dust for me.

Min

#25 AtomicAxe

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Posted 30 June 2013 - 05:34 PM


A lot of designing a clay body is making clay that matures and doesn't slump at the cone you want to use.

http://www.ceramicin...kage-absorption
http://digitalfire.c...bodies_211.html
http://digitalfire.c...t_bars_214.html

Those pages have info on testing the clays, what you want to do is limit shrinkage, while still providing a 'plastic' clay body that has strength and doesn't absorb liquids when high fired.

Ideal for you would be to try to design a versatile clay body that can get to cone 10 reduction no problem but functional at cone 6. also having your basic 4 ingredients in bag or half bag amounts in a batch would make it easier to make and produce without the pain of having bins to measure out single pound increments. sooooo ...

I would probably start with ...

lizella 25
epk 12.5
fire clay 25
neph sy 12.5
fine grog 12.5
flint 12.5

I would also try

lizella 37.5
feldspar 25
fireclay 12.5
epk 12.5
flint 12.5
fine grog ... maybe 5

From there you could probably hit it spot on ... but really it depends on your testing you do post ... so prepare for line blends to achieve what you want.

and ask offcenter also ... it's his part of the woods.

OH ... and if either of those pan out as is ... those clay bodies will be named "Funk Nasty Red: The Movie"


The more I learn about pottery the more I realize there is more i don' t know.

So thanks again to the learned ones for the info, and edumacation.

Let me just throw in I have spent some time researching making clay....not just waiting to be spoon fed


Some of my. Sources (second one a scholarly resource )

http://www.cheminfon...ceramics101.pdf
http://www.tulane.ed...ic%20terms.html
http://www.ceramicin...-your-clay-body



Lizella =earthenware clay

Epk= porcelain clay

Fire clay=
"Similar to stoneware clays, fire clays generally contain less flux (especially calcium and feldspar). Fired alone these clays won’t fully vitrify – even at high fire temperatures"

Neph Sy=can be used in a clay body when lowering the maturing temperature of the body is required....(flux, feldspathic)

Flint= " (the common name used in the industry for all forms of silica) serves as a filler, lending strength to the shaped body before and during firing"

Grog=opening material, structure, filler.......

Since lizella and epk were the givens. How and why did you select the other "ingredients"? And reasons behind proportions?

I vaguely understand some of choices but why fire clay, vs other clays?

And I'm not sure what Flint's role is here? glass former?

How would I make this body less red, more dirt ? How do I tweak formula to make epk. Dominant ingredient?

After reading yours and other posts. I realize you guys are to clay. Like a chef is to food. And say this to you as trained chef (previous career), I can tell you subtleties on braised short ribs.. Clay not so much....


Lets first start with the differences between Kaolin (EPK), Ball Clay and Earthenware clay (red clays). Generally described as a primary, secondary and tertiary clay from the source in which it was derived. Primary clays (kaolins) have very little impurities (like stray feldspars, iron impurities, etc), secondary clays such as ball clays are relatively neutral but have some impurities and will generally have traces of feldspars, iron and other ingredients in them but is more flexible and stable as an addition to a recipe than kaolin which will tend to be 'short' in comparison. Tertiary clays are very impure sources of clay and normally have high levels of feldspars, metal deposits and other impurities from silica to fireclays in them. Every step of the way that it moves from the original igneous rock to the final source it lowers in melting temperature

As a whole, when I use earthenware clays, epk or ball clay in some form will try to enter into the formula just to act as a stabalizer for the clay ... something more clay-like to make a claybody a CLAYBODY. if that makes sense .. but not always the case.

By themselves, clay that needs to vitrify and take glazes needs a little more than just clay to do it's job. that needs help from materials like silica and flux, (glass former and flux) to complete the body. You can have a clay that lacks flux and silica that will completely be fine if you don't want to glaze or hold liquids or really be anything other than sculptural ... but the silica will help glazes bond with the body and the flux will melt the clay into a solid liquid resistant object.

Now for the fireclay, Fireclay is a refractory clay that due to it's courser nature will lend itself to stability and resisting warping and cracking in firing when added to a claybody. it's also very impure so the iron deposits help make a stoneware grey and also the reason you wont find it in porcelain clays. Grog also does this too ... but in my older age have gone from putting it in all my stonewares to reduce cracking from drying and production and heat based abnormalities (cracks, dunts, etc) ... to putting it in maybe 10% of my clays.

Now with that, a red clay body will need the basic 5 to be a well rounded and versatile body (ball or earthenware clay, fireclay, flint, flux and grog) Porcelain on the other hand would be kaolin, flux, silica and maybe a hair of ball clay to make it more plastic (at the cost of purity of color) and even then I still see additions of things like bentonite and wollastonite to make it more plastic.

Hope that makes sense.




I'm sure there are a lot of people who have mixed more clay than I have but for what it's worth - I have made Jeff Campagna's Porcelain, Val Cushings and Julia Galloways, in all 3 I used 200 mesh silica. All seemed fine to me, I don't know what a finer silica would do to a body.

Min


in a clay body and in a glaze, the finer the grade of silica (thus more surface area to cover the same weight of material because of the reduced size of particle) the more it can melt into a glaze or clay body with the flux. In bodies such as stoneware and red clays that do not need a finer grade ... not needed. In things like porcelain which can be translucent with thin applications as well as the grade of the clay being a little smoother than if was courser flint ... a fine mesh like 300 mesh silica will be a benefit. The cost is stability to some degree (more that melts means more that warps) so would have to be recalculated ... but if you're already testing a porcelain body you should be calculating for reduced warpage anyways.

#26 Marcia Selsor

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Posted 30 June 2013 - 09:39 PM

I was a caretaker of a religious estate in Upstate NY. I also had a studio. from an abandoned greenhouse on the estate, I gathered up about 50 earthenware clay flower pots.
I would mix a trash can of slip, lined the flower pots with cheese cloth and a little piece of paper over the hole and put slip into the pots. I had them lined up on shelves in the basement of the mansion I where I was care taking.This made very nice throwing clay after a day or so.
it was an inexpensive way to make clay without mixers and pluggers.
Marcia

#27 Marcia Selsor

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Posted 01 July 2013 - 07:48 AM

I thought I might mention that making a slip first and letting it dry to usable consistency creates a very plastic clay body through that process.
It was used around the Mediterranean for millennia. So regardless of whatever recipe you are using, this is a great simple way to mix. You can also dry out the slip i other material: on plaster or concrete slabs, in various clothes like tied off jeans, pillow cases, etc.

As for a darker color, reduction firing would do that. Otherwise you may have to resort to something containing manganese which is not safe.


Marcia

#28 AtomicAxe

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Posted 01 July 2013 - 09:00 AM

huh. Never thought about flower pots ... that is definitely an interesting way to go.

you could even sew a .... bag ...... perhaps for the inside out of canvas so it is a little more contained.

As for the slurry method, I don't see problems with it. Just like everything else it's all in the details, use some sort of electric mixer to get a good pre-blend when it's slaked and go to town.

As for drying ... depends on the conditions. Where I'm at now, I will pour onto canvas that is sitting on a plaster bat inside then wrap the top so it's like a clay burrito ... 3 day later I wedge. If I need it today, I will still wrap like a burrito, but that clay is sitting in the sun on a big slab of concrete. It's about controlling moisture loss at that point without making it too dry in some parts, but not dry enough in others.

#29 Biglou13

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Posted 02 July 2013 - 10:40 AM

thanks for all the info big help

i have these high tech air pot/ rootmaker pots that have holes on all surfaces, and will work perfect with pillow case

when making clay in mixer ive read its approx 4 parts water to 1 part clay, (weight)

?for slurry or slake mixing what ratio water to clay?

granted too much water will correct it self in drying, im trying to calculate ball park for mixing in 5 gal buckets

? is 70-140 screen silica ok for clay body?
(im told its actually finer but has occasional large particle)
im trying to make a clay body from local material and that is what is available locally.

silica (http://digitalfire.c...celain_282.html)

"Silica Silica tends to be a very consistent and inexpensive material. Quartz grains act primarily as a micro-aggregate or framework structure for the fired matrix. In addition, some of the silica is dissolved by the fluxes to produce aluminum-silicate glasses. Too much silica in a recipe could mean lower plasticity (since less room is left for clay). However, there is also much discussion about the detrimental effects of crystobalite (i.e. dunting), whose development during high temperature firing is related to available free quartz. Thus there is some merit to lower silica amounts, especially if you have the ability to adjust your glazes to lower their expansion. The use of less silica means more clay can be added resulting in higher plasticity. A finer silica (300 mesh) reacts better with the fluxes and thus less is needed. Too little silica in a body can mean crazing glazes since the quartz mineral contributes to the low expansion that assists glaze fit. For cone 10, many technicians aim at 20-25% for expansion reasons and to provide firing stability over a range of temperatures"



ill be mixing an epk based clay body, occasional wood firing, or whatever kiln i can get in (with testing of course)
from
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
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#30 AtomicAxe

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Posted 04 July 2013 - 11:45 AM


?for slurry or slake mixing what ratio water to clay?

granted too much water will correct it self in drying, im trying to calculate ball park for mixing in 5 gal buckets

? is 70-140 screen silica ok for clay body?
(im told its actually finer but has occasional large particle)
im trying to make a clay body from local material and that is what is available locally.


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


We'll start with the clay body recipe, just remember that redart is different from lizella. So test and modify accordingly especially when that clay body is using it for color not for a main ingredient.

as for the ratio ... I don't really know sadly ;) ... I just have a big bucket of dry mix I make that is blended roughly , then just add to a bucket of water like plaster until it doesn't take any more, then add a little more and blend like a bad mofo. when it's all slaked from my dry mix .. how ever many buckets that is ... I will pour onto my canvas all at once and that is my slaking process.

for a red clay, that mesh of silica is fine. The extra iron in the clay will help it bind, though I prefer true 200 mesh.

#31 Biglou13

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Posted 11 July 2013 - 09:30 PM

If my supplier only has 320 screen silica vs 200, Will that cause a problem?
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#32 Biglou13

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Posted 18 July 2013 - 09:21 PM

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

 

ok im going to make this, using slurry method,  drill paint mixer.......tomorrow.

do i need to mix in any specfic order?

any special handling for bentonite?


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#33 Biglou13

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Posted 19 July 2013 - 12:29 PM

small disaster 

 

after reading how "sticky"bentonite is i blunged my bentonite with hot water, using a hand held mixer,  night before.

i started with 10%, 10# of recipe

ive read 4:1  is normal ratio  h20 : dry

 and vaguely recall 6:1  for slurry technique

i estimated appox 7:1   for a loose mix (not to burn up drill)

water is approx 8 pounds/gal

so for 10#   dry approx 40# water or approx 5 gal

i opted for approx 7 gal

 

 

way too much water!!!!!!!

i kept adding dry ingredients in (.05 x100) increments of recipe   until i ran out of one ingredient.

well at best its a little thicker than glaze consistiency.

starting ratios are way off  im at aprox 0.6:1  dry to h2o   (barring any mistakes along the way)

 

All is not lost, i hope

its aging..... settling..  on porch now.... will decant clear water off in next day or 2.

 

note:  after assembling all ingredients and equipment  it wasn's as much a P.I.T.A.  as many have implied. internet taught me much bentonite for detox

 

......live and learn......


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#34 Min

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Posted 19 July 2013 - 04:57 PM

When I tried mixing a claybody with bentonite I dry blended it into the other ingredients then added the mixed dry clay to water. I did use a mixer/pugger so maybe this way wouldn't work with the slurry method but I don't see why not. One of the commercial bodies I use I bought in 50 lbs sacks of dry, pretty sure it contained bentonite not macaloid, I mixed that with water the same way. 

 

I noticed your recipe has a fair bit of nepsy in it, slightly soluble, any problems with decanting too much water do you think? I was wondering if you should mix up a small batch of your clay recipe dry and add it to your really wet mix instead of decanting, just a thought.

 

Min



#35 Biglou13

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Posted 19 July 2013 - 06:17 PM

i kept adding more dry mix until i ran out of one of the ingredients  silica. i wont be able to mix more until i can make it to supply house, next week

 

are you saying nepSy goes into solution with water and wont settle out/down?

 

how do you mix yours,  how much water to dry?


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#36 Min

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Posted 19 July 2013 - 08:08 PM

i kept adding more dry mix until i ran out of one of the ingredients  silica. i wont be able to mix more until i can make it to supply house, next week

 

are you saying nepSy goes into solution with water and wont settle out/down?

 

how do you mix yours,  how much water to dry?

 

No, what I meant was nepsy is slightly water soluble, some of the minerals will be in the water. Therefore if you decant a fair amount of water you will be throwing a bit out, soda, in this case. I don't know if it would be significant or not.

 

Moist clay is usually about 30 to 70 ratio of water to clay.

 

I mixed in my mixer / pugger (Bailey has one that is actually a mixer / pugger combination, not just a pugger like some)

 

Min



#37 Biglou13

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Posted 19 July 2013 - 11:20 PM

Yeah my ratio was way off found my notes too late. Starts with 4:1. Dry to h20......(Dumas) oh well

Well I've read that the flux nature with the silica will be greater due small slica size.(I used smaller mesh).... But with the way it's I'll be slightly over fluxed.. Hope the nep Sy loss won't be to great
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#38 oldlady

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Posted 20 July 2013 - 06:31 PM

just checking.......... i replied to your question about order of ingredients and bentonite. it does not appear here. wonder what is going on?
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#39 Biglou13

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Posted 20 July 2013 - 07:52 PM

Glitch

can u repost or pm me please
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#40 Marcia Selsor

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Posted 20 July 2013 - 09:56 PM

there may be. Check the brand label. Mixing your clay using some store bought material is still cheaper than buying moist clay which is 30% water. But consider you want to go to cone six. It could be really difficult to dig clay that matures at that temperature. Listen to Atomic who offers a clay body with two of your local ingredients plus commercial clays to get you what you need.
I mixed a nice cone six stoneware for many years but not with Lizella. You need the right ingredients. If you want to dig lay and be natural, work with earthenware like Lizella that will mature about Cone 04 to 1maybe.

marcia






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