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

[glazenerd]

Just now, JBaymore said:

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

best,

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

 

True enough, but I find clay chemistry very fascinating.  Clay has a code: a systematic set of reactions that are relatively easy to understand: once you break the code.

tom

[Guest JBaymore]

1 hour ago, glazenerd said:

True enough, but I find clay chemistry very fascinating.  Clay has a code: a systematic set of reactions that are relatively easy to understand: once you break the code.

tom

Tom,

Yes.... but the point of the starting question from a hobbiest is that he is thinking of working on developing a clay body as a solution to not having a local supplier produce a body that works for him.  And cost is a concern.  So investing the kind of time it would take to really understand this stuff (time is money) is time away from actually making stuff.  If he has that kind of techie interest, fine.  But there likely are solutions that would make more sense for most folks.  (There is also the equipment and health risks issues to address.)

Mere mortals do not typically go into the depth concerning developing clay body understanding that you have. 

best,

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

[neilestrick]

The other problem of having your own body mixed by your supplier is that before having them make the big batch, it will take several hundred pounds of any body to effectively test it once you've got it close. It takes throwing everything in your repertoire, testing all of your glazes on it, several firings, different drying conditions, etc. If it's not working, then it's mixing another 300 pounds of test clay and repeating the process. Mixing 300 pounds of clay without the proper equipment is no small feat in itself, and it's absolutely necessary before going to big batches. It's no small thing to commit to 2,000 pounds of a custom mix. You could get 200 pounds into it and realize it's not as good as you thought.

[Tyler Miller]

Neil,

You've hit on something there.  I know of a potter who got into making his own clay bodies.  Made a few test small batches (under 50 lbs), thought "success!" and passed some out to friends.  Dunting happened on an epic scale.  Much embarrassment, many apologies.

I dig my own clay sometimes.  Took easily 500 lbs to figure out the clay seam I use and how make a body work. 

[kraythe]

Again, to be clear I have not necessarily WANTED to make a clay body, I just want something that I can glaze to reliably. I have used premixes with lousy results and a couple of self mixes though who knows if I got those right, I am just learning the chemistry here. What I find annoying is when a supplier wont tell me basic information about a clay body and when I ask they shrug and say "just experiment" which is, in my opinion, annoying. 

[Tyler Miller]

@kraythe

I think the subtle takeaway from what we've been saying is that you've maybe set an unrealistic expectation for what the information you've hoped to obtain will provide.  

1)Knowing what's in the clay cannot give you a calculable COE for the clay body--and glaze software won't give you that info.  This info must be obtained via expensive experimentation that some manufacturers just don't bother with.  It strikes me that many posted clay body COE's are erroneous anyway.  

2)  Even if you had those numbers, you would still have to test the glazes.  Glaze software COE calculations are more a relativistic fiction useful in their relation to one another rather than an absolute concept.  Some fluxes don't work the way the software attempts to predict.  Calculations don't guarantee success, just point in its general vicinity.

3). Testing is a necessity, without which you're not going to make successful pots.  It's something we all have to do.   You have the choice of picking clay bodies and testing them with glazes you like or making clay bodies and testing them on their own, and then testing them with the glazes you like.  Far more work than trying to make what you have work for now.  Exponentially more.

 

[neilestrick]

To expand on what Tyler said, each glaze formulation program will give a little different COE for the same glaze. For instance, I know that Hyperglaze, which I use, tends to give lower numbers than Insight, which others on the forum use. So while my clay supplier may be able to tell me the COE of their clay, it may not be calibrated with my glaze software. The only way to know for sure is to test some glazes with varying COE and see which fits the clay body best, and use that as the baseline for your tests, using whatever glaze software you use. Add to that the differences in firings and the numbers from the manufacturer aren't worth much. As with all things in ceramics, the answers to your predicament come down to 'it depends' and 'run some tests'.

[Guest]

On 10/22/2017 at 6:11 PM, 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.

Through an internet search I found this link for this clay you are asking about.  http://jeffcampana.com/clay-body-revisited/

There are others here that understand the details about this clay more than I do. Personally I would move to another clay body

Based on the link above I can suggest other suppliers close to you in your neck of the woods

Google Link

And a list of local potters that may help you find a local source of clay

Google Link

Good Luck

[Denice]

I would move away from the Campana clay formula, you said it was Cone 6 to 8.   This clay won't vitrify unit it is fired to Cone 8,  if you glaze fire at C6  mugs will leak and your work will break easier.    You can't blame clay companies for not wanting to give away their formula's that is how they make there living.     Denice