Making clay 101

[Biglou13]

Ok I want to make my own clay.

 

Everyone says cheaper to buy. But I still wanna do it. (Hardheaded, mom said so)

 

I'm over digging locally. Romantic but sounds like to much work.....

 

epk is mined near where I live, And Lizella is a day drive.

 

I'd like to make a clay with these 2 as major components. Lizella and EPK. (If not. Edgar lives closer)

 

The usual suspects (supplies/raw materials) should be available from local supplier.

 

What I know about making clay I learned from the internets (and i stayed at holiday inn), and from some geat articles here at the CAD."raw materials"

 

Perhaps one / some of the Jedi masters will enlighten. This (not so) young padwan learner, with a little how to/ 101.

 

I currently only have access to cone 6 electric, so it would,have to work starting in that range.

 

I like groggy bodies so that would be good. But that is a easlily added option

 

It would be great if clay could also fire higher, and perform and look great in wood fire. (Hey a young padwan can dream)

 

I'm also a fan of darkish clays.... Shouldnt be problem with lizella, but I do dislike boring terracotta color (not to discriminate against the blancos) and color is secondary to performance.

 

Please advise.......

 

Again any help is always appreciated. ( so is the ocassional ribbing)

[AtomicAxe]

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"

[TJR]

If I knew what Lizella clay was, I could put my oar in, so to speak. If you are near an EPK deposit, you are laughing. You would need a ball clay as well for plasticity. Since EPK is a refractory clay you could even consider making refractories like kiln posts out of it.Is Lizella a ball clay?
Try a 50/50 mix, 70/30 [Epk,Lizella [, and 30/70[RPK and Lizella.
Make some shrinkage bars to see how it holds up, and make some vertical test tiles to see if it slumps.
TJR.

[OffCenter]

If I knew what Lizella clay was, I could put my oar in, so to speak. If you are near an EPK deposit, you are laughing. You would need a ball clay as well for plasticity. Since EPK is a refractory clay you could even consider making refractories like kiln posts out of it.Is Lizella a ball clay?

Try a 50/50 mix, 70/30 [Epk,Lizella [, and 30/70[RPK and Lizella.

Make some shrinkage bars to sea how it holds up, and make some vertical test tiles to see if it slumps.

TJR.

 

 

No, Lizella isn't a ball clay. It is often called an earthenware or even terra cotta because of its color and original use for flower pots fired to about cone 010, but it is really a cone 8 stoneware. Best color around cone 5. Will go up to cone 10 but will start to deform if held at 10 for long. Beautiful clay but even at cone 8 or above will leak unless neph sy is added to it.

 

Jim

[Min]

From Val Cushing's Handbook:

 

Fires orange brown "easy" platic body

 

Goldart 30

 

Hawthorne 30

 

Lizella 40

 

Another one, dark brown to black, this one is oxidation only as it will melt or become brittle in reduction due to high iron content:

 

C&C Ball Clay 10

 

Goldart 15

 

Hawthorne 15

 

Blackbird 10

 

Lizella 50

 

One more, cinnamon throwing body:

 

OM4 20

 

Goldart 35

 

Hawthorne 15

 

Lizella 20

 

Soda spar 10

 

And if you want a tan colour and a sandy body:

 

OM4 25

 

Goldart 25

 

Hawthorne 25

 

Lizella 10

 

Talc 5

 

Nepsy 10

 

I have made up a couple of his white bodies, the translucent porcelain is terrific, haven't used any of the above recipes. Maybe a blend of the second body with one of the others?

 

Min

[futurebird]

Is there a good book that I could read that would teach me about this topic?

[AtomicAxe]

Figured I should also give you my old ocmulgee ^10 body ... if you can find a substitute for AP Green (no longer available) ... from what Offcenter has said, lizella is just a hop skip and jump from ocmulgee so the clay should be similar if not exact.

 

AP green - 33

OM4 - 33

Ocmulgee - 17

Grog - 10

Spodumene - 7

 

Just a brief search on digital fire suggests that Plainsman fireclay is a substitute but I've never seen it before.

[oldlady]

smooth redbrown clay without grog fires at cone 6

100 lb redart
100 lb XX sagger
plus
water
makes more than 200 lb great clay for under $25.

from Robin Teas who found that her students did not want to 'waste' their expensive purchased clay to practice throwing. '

[AtomicAxe]

I hate 2 ingredient clay bodies. And redart is nothing like lizella/ocmulgee.

 

 

That being said, here is a few from val cushing back in the day that use ocmulgee and in his ^4-^6 clay bodies ... you can probably substitute pine lake fireclay with hawthorn or just about any fire clay ... but easy enough to do.

 

http://www.studiopot...les/art0009.htm

[oldlady]

hey, axe, you don't like 2 ingredient clay but you are not the person who asked. the heading is making clay 101, i think that is for a basic clay that will work at cone 6. i didn't see anything in the original question that prevents the use of purchased dry ingredients. nothing says lizella and epk are required in the recipe.

 

this dark red clay works well at cone 6, is easy to throw and i used it for several years with much success. it is a good, basic clay. add grog if you like. that will make it a 3 ingredient clay. much better.

 

go easy on those of us without your technical skills.

[AtomicAxe]

hey, axe, you don't like 2 ingredient clay but you are not the person who asked. the heading is making clay 101, i think that is for a basic clay that will work at cone 6. i didn't see anything in the original question that prevents the use of purchased dry ingredients. nothing says lizella and epk are required in the recipe.

 

this dark red clay works well at cone 6, is easy to throw and i used it for several years with much success. it is a good, basic clay. add grog if you like. that will make it a 3 ingredient clay. much better.

 

go easy on those of us without your technical skills.

 

 

1. Chill out.

2. What I expressed was personal preference, nothing technical.

3. I still hate 2 ingredient clay bodies.

 

4. ...

 

I'd like to make a clay with these 2 as major components. Lizella and EPK. (If not. Edgar lives closer)

 

 

Boosh.

[Guest JBaymore]

Be careful taking bodies with little devloped glassy phase (becasue of no spar, frit, or neph. sy. content .... yeah...spodumene counts here.....) up to higher temperatures above the 1100 C / 2012 F range........ particularily with longer firing cycles. They are prone to having the non-melted silica on the body converted to the cristabolite form of SiO₂ ..... which has a nasty huge impact on the COE of the body. Can cause dunting issues on kiln cooling...and also cracking in the domestic oven temperature range. The amount of cristobolite developed is linerally related to the time spent above 1100 / 2012.. ..... twice asl long... twice the conversion level.

 

Some of these above recipes would tend to have that issue, I think. Cone 6 is typically reached above that temperature for most typical rates of climb.

 

best,

 

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

[oldlady]

John baymore,

 

could you be more specific about which formula you are referring to in the above comment?

[Guest JBaymore]

Body formulations with nothing supplying additional sources of fluxing materials to cause more of the SiO₂ in the clay components (both as trace admixtures and from the kaolin/metakolin silica ejection) to convert to a glassy phase. Depending on the firing range, if you don't see an addition of feldspar, neph. sy., frit, sometimes spodumene, or the like in the formulation..... there there is the possibility of the issues I mentioned.

 

best,

 

 

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

[Min]

Be careful taking bodies with little devloped glassy phase (becasue of no spar, frit, or neph. sy. content .... yeah...spodumene counts here.....) up to higher temperatures above the 1100 C / 2012 F range........ particularily with longer firing cycles. They are prone to having the non-melted silica on the body converted to the cristabolite form of SiO₂ ..... which has a nasty huge impact on the COE of the body. Can cause dunting issues on kiln cooling...and also cracking in the domestic oven temperature range. The amount of cristobolite developed is linerally related to the time spent above 1100 / 2012.. ..... twice asl long... twice the conversion level.

 

Some of these above recipes would tend to have that issue, I think. Cone 6 is typically reached above that temperature for most typical rates of climb.

 

best,

 

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

 

 

John, would you consider the iron content in some of the above clays an adequate flux if firing reduction?

 

 

Min

[oldlady]

OK

 

now i feel like a 2nd grader in a calculus class. i will go to my corner and sit.

[Biglou13]

OK

 

now i feel like a 2nd grader in a calculus class. i will go to my corner and sit.

 

 

It usually takes me a few days and hours on the Internet before it sinks in and I start to understand.

[Guest JBaymore]

John, would you consider the iron content in some of the above clays an adequate flux if firing reduction?

 

The iron in the reduced FeO state is an active flux on silica (SiO2), for sure, and it begins its action at quite low temperatures. So yes, it will add some fluxing of the available silica and keep that silica from potentialy converting to the chrstobolite phase form. Unfortunately, iron fluxed silica glass is very brittle... so the body's glassy phase in that case is not a very optimal one to use to "glue things together".

 

Plus the iron/silica melt has a low melting temperature and also a low volitilization temperature... possibly accounting for some additional bloating issues.

 

A particulary bad combo is a somewhat high iron body with inadequate sourcing of other fluxes. You end up with a brittle body that is getting "loaded" upon uneven cooling (or reheating in food service) by excessive COE factor from the cristobolite... and BANG..... dunting.

 

best,

 

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

[Guest JBaymore]

OK

 

now i feel like a 2nd grader in a calculus class. i will go to my corner and sit.

 

 

 

Body formulations with nothing supplying additional sources of fluxing materials to cause more of the SiO₂ in the clay components (both as trace admixtures and from the kaolin/metakolin silica ejection) to convert to a glassy phase. Depending on the firing range, if you don't see an addition of feldspar, neph. sy., frit, sometimes spodumene, or the like in the formulation..... there there is the possibility of the issues I mentioned.

 

That (in red) is the key phrase in there..... any of the recipes that don't have those materials listed are the ones I am talking about.

 

Does that help?

 

best,

 

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

[Biglou13]

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"

 

 

Found some fire clay. At local hardware/ag store.

 

Is this any different than fire clay fom pottery supply?

[Mark C.]

it can be.

Mark

[Biglou13]

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.ceramicindustry.com/articles/ppp-understanding-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....

[Biglou13]

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?.

[Min]

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

[AtomicAxe]

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.