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kraythe

Can I get some opinions and answers on this clay body.

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As some have read I am not happy with the clay body I am using because I cant know vital stats about the body because they wont tell me what is in it.  So I have been considering having a mix that I know about before hand and can control its contents. Realizing that it would be foolish to try to do it from scratch on my own, as I am a hobbyist and not a pro,  So I have been surfing the internet looking for recipes and that is actually not easy as many people keep their formulas to themselves. I did find an excellent article from Jeff Campana on a clay body an would like to know your opinion on it.  I also have some questions: 

  • Would it be worth replacing the Minspar 200 with Nepheline Syenite to get a whiter body or could that lead to problems. 
  • Is the usage of Tile #6 Kaolin just to make the body more workable on the wheel? 
  • I am wondering if it would be possible to raise the thermal expansion to the 7 range? I tried to add Talc in Digital Fire and it LOWERED the expansion, which confused me to no end. What compromises do I have to make (whiteness or something else) to raise the calculated expansion or I will have just as many glaze fit problems as I have now. 

Thanks for your time.  The original recipe is below:

Campana.PNG.8de37e902d20bc9cfee92765c29608d2.PNG

Edited by kraythe
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I cannot address cone 6 bodies at all(since I use cone 10 bodies) but I can say using a commercial body is about 1000 times easier for a hobbist-I suggest you just experiment with a few until you find one you are happy with. 

If you are going to make one -I assume you have a mixer and a vacuum pug mill or a all in one unit like a petter pugger? If that's a  yes than making a body in small quantities makes a bit of sense.

D.M.Ernst likes this

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23 minutes ago, Mark C. said:

I cannot address cone 6 bodies at all(since I use cone 10 bodies) but I can say using a commercial body is about 1000 times easier for a hobbist-I suggest you just experiment with a few until you find one you are happy with. 

If you are going to make one -I assume you have a mixer and a vacuum pug mill or a all in one unit like a petter pugger? If that's a  yes than making a body in small quantities makes a bit of sense.

Well currently the only commercial porcelain cone 6 clay body I have access to is the one messing with me. Any others Id get killed in shipping. If I was able to find the right formula my supplier will mix 2000# of it for me using their equipment and that is fine. 

Edited by kraythe

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It's been a while since I've used INSIGHT, but I'm pretty sure glaze COE can't  be used to calculate clay body COE, which should be established empirically with a dilatometer.  COE of glass vs crystalline materials, etc.  The number you have is what would result from a cone 14+ glaze of the same composition as the cone 6 clay body you're shooting for.

If you want consistent, craze free results, you will save yourself a load of work and headache just buying a few boxes of different clays and trying out your desired glaze set on them.  You'd have to do this no matter what if you formulate your own body, even if you had the dilatometer to establish an absolute CoE on your own .  These tests are the important part, especially since some ingredients don't play ball with glaze software.  Sometimes that perfectly dialed-in glaze crazes or shivers, despite giving no on-paper reason.

So, my advice, don't sweat not having an ingredients list.  Get a few different bodies from a few different makers (Laguna, Plainsman, and whoever else), make some tiles, test your glazes.  If  they craze or shiver.  Tweak a little. Use the one you think works best for functional ware.

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maybe your supplier can order a few others to try-if not have  another supplier send to you in the if it fits its ships flat rate boxes that fit two pugs (50$ for the flat rate of 19$) then have your supplier order that clay that works for you.This is all if you live in the US since I do not know where your location is>?Just be sure your body works well before you have a ton made.

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(If you want consistent, craze free results, you will save yourself a load of work and headache just buying a few boxes of different clays and trying out your desired glaze set on them. )

Tyler said it spot on.

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8 minutes ago, kraythe said:

Well currently the only commercial porcelain cone 6 clay body I have access to is the one messing with me. Any others Id get killed in shipping. If I was able to find the right formula my supplier will mix 2000# of it for me using their equipment and that is fine. 

Try Roadrunner ceramics in San Antonio,  it's about a 95 mile drive and they sell a variety of clay bodies.  Closer than me to my supplier.

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40 minutes ago, Tyler Miller said:

Try Roadrunner ceramics in San Antonio,  it's about a 95 mile drive and they sell a variety of clay bodies.  Closer than me to my supplier.

The same problem will be there, If I don't know hats in it, don't know the expansion, it will be a pain. BUt maybe other clays will be more cooperative, I am amenable but driging to San Antonio for clay is a bit much. I don't make my living through clay. Its ah hobby is all. 

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Nep Sy does not add fired whiteness.. A myth. Although if spars have metal oxide contaminants; they can  altar brightness and add color. tile 6 kaolin does not add plasticity, it adds larger particle sizes. Good in certain applications, but at cone six mostly potter's preference. 

In the other thread: I posted a basic cone six formula.

50% kaolin, 30% spar! and 20% silica.  So insert

50% grolleg, 30% minspar, and 20% 325 mesh silica. (Nep Sy causes problems in a clay body)

add 2-4% macaloid. v-gum is a great plasticizer as well, but you will need blunting equipment.

the amount of plasticizer is solely preference, 2% minimum and 4% maximum. 

You now have a cone six Coleman porcelain body.

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By the way..... Since you are hand mixing: it will take 3-5 days for cation exchange to take place. (. Achieve full plasticity.) 

dry blend first, then add water. 

One of these days I will make a video on slake mixing clay...an old plaster trade method of blending. At the moment I am too old, tired and too crabby.  Enjoy.

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Guest JBaymore
1 hour ago, Tyler Miller said:

It's been a while since I've used INSIGHT, but I'm pretty sure glaze COE can't  be used to calculate clay body COE, which should be established empirically with a dilatometer.  COE of glass vs crystalline materials, etc.  

You are remembering that correctly, Tyler.

best,

 

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

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Guest JBaymore

Remember that your clay is actually close to the cheapest part of your operation.  It is your TIME that is important and valuable and expensive.  Mixing clay,.... heck even reclaiming clay.......... is very time intensive.  Even with decent equipment.... and that equipment will cost you a lot of money.  Money that will become part of your "clay cost" anyway.  As a hobbiest, do you want to spend the time you have to devote to the hobby in mixing clay, or improving your forming and decorating skills and making pieces?  Tyler and Mark are right on.......... try to find a commercial body that works and then tweak glazes to fit.

best,

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

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3 minutes ago, JBaymore said:

Remember that your clay is actually close to the cheapest part of your operation.  It is your TIME that is important and valuable and expensive.  Mixing clay,.... heck even reclaiming clay.......... is very time intensive.  Even with decent equipment.... and that equipment will cost you a lot of money.  Money that will become part of your "clay cost" anyway.  As a hobbiest, do you want to spend the time you have to devote to the hobby in mixing clay, or improving your forming and decorating skills and making pieces?  Tyler and Mark are right on.......... try to find a commercial body that works and then tweak glazes to fit.

best,

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

I don't disagree, I wish this one would work better. But It doesn't. Reality intrudes. And if I ship it online the shipping will be as much as the clay. 

Unless you know a maker of a nice Grolleg based cone 6 porcelain with 6.5 to 7 expansion who doesn't kill for shipping. If so, please do tell and I will try them. 

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No matter what the ship charges are while your are experimenting to find your perfect body it really does not matter. Once you find it then you figure out how its going to get to you in larger quanitys-most suppliers carry a few lines of clay from several manufactures  and can order when they order the big order from them. Now I assume you are in Texas-and there should be lots of choices from several suppliers. Since its a hobby you have lots of time to figure this out and dial it in.Making your own clay is not for the weak of heart.

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@ Kraythe,

Last couple days you’ve had questions regarding low COE porcelain, low COE clear glaze, how to lower the COE of a tea dust glaze, replacing a frit and having a custom body mixed up. Bravo to you for asking so many questions, but…..

With all due respect I think you need to slow down and listen to what Mark, Tyler, David, Neil,John and others are saying. They have a wealth of knowledge and experience. Ceramic work is not a sprint, it’s a marathon. I would respectfully suggest you take the time you need to either try out a bunch of clays and test the heck out of them before committing time to making a whole whack of pots or test the clay you already have and see if the glaze COE does have to be as low as you think it does. Plainsman Clay up here in Canada doesn’t publish COE figures, Georgies in OR, Seattle Pottery Supply and Tacoma ClayArt in WA don’t either. I really wouldn’t get too hung up on only trying clays that supply the COE data. Try a bunch, put your glazes on them and see what happens. If you LOVE the clay you currently use then try out some (fully melted gloss) glazes with different COE’s and see what happens.

D.M.Ernst and Rae Reich like this

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2 hours ago, kraythe said:

Well currently the only commercial porcelain cone 6 clay body I have access to is the one messing with me. Any others Id get killed in shipping. If I was able to find the right formula my supplier will mix 2000# of it for me using their equipment and that is fine. 

I recommend reading up on published recipes for ^6 clay bodies. It could take you a long time to develop one on your own.

Marcia

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2 hours ago, kraythe said:

The same problem will be there, If I don't know hats in it, don't know the expansion, it will be a pain. BUt maybe other clays will be more cooperative, I am amenable but driging to San Antonio for clay is a bit much. I don't make my living through clay. Its ah hobby is all. 

I use to drive to Austin 360 miles one way when I lived in Brownsville and the San Antonio supplier closed. Where are you getting your chemicals for your experimental clay bodies?

Marcia

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Guest JBaymore
52 minutes ago, kraythe said:

I don't disagree, I wish this one would work better. But It doesn't. Reality intrudes. And if I ship it online the shipping will be as much as the clay. 

Unless you know a maker of a nice Grolleg based cone 6 porcelain with 6.5 to 7 expansion who doesn't kill for shipping. If so, please do tell and I will try them. 

Just by way of background, I use multiple clay bodies for various types of pieces... some are my own recipes I mix, some are commercial, and some are commercial that I then modify.   I do have a decent batch clay mixer (over 40 years old now) with a good ventilation setup on it....which certainly helps.  (To buy that equipment now would cost many thousands of dollars.)

One clay body I use (in smaller amounts) I have shipped literally all the way across the USA from the other coast.  No one else makes anything like it.  The shipping is WAY more than the cost of the clay.  Even given that.... clay is cheap (including the shipping costs).

As far as clay/glaze fit goes, altering glazes is far easier than developing GOOD clay bodies. 

best,

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

 

 

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When I lived in Iowa, I used to drive up to Minneapolis to buy clay. It took a full day to go up and back, but we always made a good day of it and had a nice lunch, did a little shopping in the big city, etc. It's worth it versus mixing your own clay. If you do not have the equipment and ventilation to mix clay bodies properly and safely, then it's going to be way more work and risk than it's worth. Take a drive and get a sampling of other clays, or call another supplier and see if they'll ship you 5-10 pounds each of several of their clay bodies. When you find one that works, just buy enough that the shipping isn't too outrageous per pound. That may mean buying 500 or 1000 pounds, but it'll keep for a year or more. And even expensive clay is cheap when you break it down to the cost per pot.

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John:

i find developing "good" clay bodies rather easy myself...then again I bought the Ronnco "clay o matic"  get the deluxe model and it will throw, trim, and glaze for you as well. I love Ronnco products, their "hair in a can" is the bomb.

Tom

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Really. You won’t drive 95 miles - a day trip to get maybe half a year if not a years supply, but you’ll spend so much more time in mixing claybodies. 

My circle is full of hobbyists and we do at least that much driving to get cheaper clay. 

The ones I know would much rather play with firing and glaze making I guess because they have found a claybody that works for them.  I guess it’s more exciting playing with 10gas. 

Now if you are passionate and intrigued by the constituents of a claybody then it’s a whole different ballgame. 

I am lucky because where I live within a 100 miles lies great ceramic stores and clay companies that stock a wide varieties of claybodies. 

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22 hours ago, kraythe said:

If I don't know whats in it, don't know the expansion

Just ask/email the supplier the COE of their clay.  I'd be surprised if they don't know it and I'd bet they would be willing to supply it.

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Guest JBaymore
43 minutes ago, glazenerd said:

John:

i find developing "good" clay bodies rather easy myself...

Look at the time and years you have put into working to understanding clay bodies already.

best,

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

 

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