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Mixing Black Clay Body - Cone 10 - Need Expertise


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#21 High Bridge Pottery

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Posted 13 July 2014 - 01:31 PM

Would the 10% feldspar make much difference to the glaze fit? I don't know as I have never made a clay body or anything. I think that is the more important problem.


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#22 Rebel_Rocker

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Posted 13 July 2014 - 03:41 PM

 I take it that it will have an effect.

 

 I will be remixing some clay next week to find out :D

 Would have been much easier to mix up five small balls with different amounts of feldspar and thrown 5 bowls to test first though,.



#23 Wyndham

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Posted 13 July 2014 - 03:53 PM

You may also have issues from time to time because the slop clay will change with different people using different clays and amounts, maybe a little, maybe a lot.

Wyndham



#24 phill

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Posted 13 July 2014 - 04:05 PM

 


 

Maybe the instructor would have NEVER anticipated that this particular student would suddenly go off and produce a whole body of work with the untested reformulation and even plan on showing the work produced....... without taking all the knowledge that they already had about ceramics and doing things like the necessary TESTING WORK before ever doing such a thing. 

 

I again come back to the fact that we have NO idea the context of this whole discussion.


 

 

 

 I worked on this stuff over the course of weeks, 4-5 hours a day (6 days a week) in the same studio as instructor open studio AND class time . Sitting at wheels where we could talk and look each other in the eye. Even discussing the forms (he complimented me on every one of them) as I went. It's the yearly student/instructor show (so I know he knew I was working on pieces for it, we discussed it). In fact the pictured piece was fired in time for the show only because he announced there would be one final firing for it.

 

 All my work isn't lost, I still have 5-6 on the shelf, change of plans, they just won't be glazed.

 

 But again, I didn't go off on a wild tangent, I just didn't test with any amounts of feldspar. This is the first time I have formulated a body and I did it to his exact specs. (at least the ones he gave me). He watched me mix it, he had me test  a coil for color (only), and I made about 10 test tiles with glazes (the test tiles haven't cracked). Then he watched me make 50 lbs of work and start mixing up another 50 lbs batch (as I still assumed his guidance was right) .

 

 This isn't something I did out of sight, it was with his guidance right under his nose and the process lasted several weeks with everyone in the studio asking me about it, etc...He was well aware of every single thing I did regarding this process.

 But at the end when it failed he said 'Well I do put 10% Feldspar in mine', 'You should have tested'.

 

 The only way I would have known I needed Feldspar would have been to have my instructor tell me, or to second guess and look up recipies online and try to formulate myself.

 

It seems like you are still hanging on to this idea that your cracked pieces are the instructor's fault. Did you mix the clay or did he? Did you make the pots or did he? 

 

If he mixed the clay and threw your pots, then yes it would be his fault. But he didn't, YOU did those things.

 

It is common knowledge to test before you proceed. This isn't just in ceramics, but in just about everything. Want to know why It is common knowledge? It's because if you don't know to test before proceeding, then you will learn very quickly because of mistakes like this. Thus it becomes common (moreover significant) knowledge to you. 

 

Maybe the instructor didn't think adding feldspar was important? Maybe he didn't realize for some other reason, maybe he simply forgot. Big deal, it's life. Stop whining, blaming other people, and hoping for immediate satisfaction and perfection. Don't blame the instructor for your bad pots. That is entirely on you, fair or not.

 

Regarding your glaze popping off your pots--that sounds like shivering. I worked with potter S.C. Rolf when his clay/glazes were shivering. Huge splinters would pop off overnight and be laying beside the pot in the morning. The clay and glaze are different in that the clay shrinks a significant amount more than the glaze when cooled, which pops the glaze off in large pieces sometimes, especially around corners, edges, or points of major stress. Interesting that this might happen with a shino, as many shino's are high in clay and generally craze. Also note that one glaze may fit great after testing but another may still shiver. Glazes have different materials and chemical makeup in them and thus inherently have differing characteristics. This is common knowledge too so heed the warning. 

 

Look here for more info on shivering. In this case it would probably be easier to adjust the clay body than the glaze. By the way, that shino you used looks fantastic on that clay body. You should share the recipe here for your fellow ceramic arts daily potters. Good luck with your clay body.



#25 Marcia Selsor

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Posted 13 July 2014 - 05:28 PM

S. Dean,
I agree that I think this is wrong too BUT instructors are now expected to share all their intellectual property rights with the university without compensation. I think we don't know the whole story on that end of this issue. On the other hand, I don't support misleading a student to mishaps.
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#26 High Bridge Pottery

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Posted 13 July 2014 - 07:03 PM

I know a few people (myself included) who although they understand it is best to test they love to hope and dream  :mellow: Many times I have cursed myself in hindsight and slowly learnt to be patient with just about everything.

 

Still who doesn't like a good cut corner.

 

So this clay body is a mix of clays fired with 50% C red and 10% feldspar? What is C red?


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#27 Babs

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Posted 13 July 2014 - 07:59 PM

If the class was on developing clay bodies aka Big Lou then the instructor is certainly questionable or forgetful.

However if it's a general class or other and a student has an idea out of left field then yes guidance but not totally taking on the swing to the left.

Developing clay bodies  haven't done it but I'd be reading my butt flat and checking out a number of sources and testing. Evident here many times no free lunch and no easy trips. Spoon fed, what happens when the spoon operattor is not in the room?.

Body glaze fit knowledge might have to occur too.

All of us will have empathy but prob not sympathy.

The term was instructor, not educator, now our Benzine would have done the homework and tested then taught for his students! :)  so his students had success.



#28 Biglou13

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Posted 13 July 2014 - 09:02 PM

C red = Carbondale red

http://digitalfire.c...e_clay_186.html

I was surprised to not see black bird, manganese, alberta additions to this body.
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#29 Marcia Selsor

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Posted 13 July 2014 - 09:21 PM

me too. It certainly is a black clay.
Marcia

#30 JBaymore

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Posted 13 July 2014 - 10:16 PM

Extremely high iron, fored in reduction.  Will have reall issues for larger pieces.  Touchy as hell to fire.  Reduced iron oxide as a flux produces a very poor very brittle glassy phase early in the firing. 

 

I use a simuilar body at cone 10 -14 in the wood kiln.  SLIGHTLY less iron content, I think.  Only for small pieces.  Looks stunning with a real Nuka.  Probably a 50% failure rate.

 

It can be done......... but you have to know what you are doing.. and know the limitations.  Taken me years to prefect using it.

 

best,

 

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


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#31 Mudslinger Ceramics

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Posted 14 July 2014 - 06:14 AM

I do mix several of my own clay bodies and I don't forget the recipies because I WRITE THEM DOWN! in my technical journal,

so I disagree with the majority here...

 

...if he wanted to genuinely share his recipie for this clay body then he could have checked his OWN records...

 

...if he gave the recipie 'off the top of his head' then he is responsible for the omissions he forgot...

 

...if he did not want to really share the recipie after all then he could have kept his mouth shut!......and sent you to the internet, CAD or the college library to find your own information which would have rightly left you with all the responsibility for the setbacks

 

I have had several lecturers and instructors over the years and I did believe them and tried all they would teach, but to be fair to teachers I didn't commit 45kgs of work all at once. I was usually testing anyway so I'd toss a few things in each load or else fire up my small electric kiln overnight because I am way too impatient to wait 4-6 weeks to see a result.

 

Shame about your experience but the lesson is learnt and will be good to see your final results.

 

Irene


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#32 Biglou13

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Posted 14 July 2014 - 07:17 AM

Irene .....I just made a 72Kgs. "Test" batch of clay............keeping fingers crossed.........(in this case it's a "known" recipe)

I my case it's the Internet leading the blind (me)

I do have to say its quite interesting to see one full off piss and vinegar, and courageously creating work.... Reminds me of someone I know........

Imagine the art world if only the "safe" route was taken.

Risks must be taken but as I age these risks are more and more calculated
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#33 Benzine

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Posted 14 July 2014 - 08:57 AM

One thing I have leared from teaching for 40 some years is that when you hear a story being told by someone else about what transpired... you are not always getting the 'whole picture'.  You are getting a single viewpoint on the genesis of the situation.   

 

Sometimes what the student hears/sees and what the instructor was saying/doing are completely different.

 

It would be interesting to hear the instructor's side of the same story about how the situation reached this point.

 

Iverall, Chris summed it all up nicely in her posting above.

 

best,

 

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

 

Very true John.  There have been many times, where I tell a student how to do part of a process, then inevitably something goes wrong.  I ask them what they did, and the explain some/ most the steps correctly.  However, they omitted one of the parts.  I ask them why they didn't do that part, and the either tell me, that I didn't tell them to do that, or just say they forgot.

Odds are, they were just listening for a certain part of the process, that they thought they needed, thinking they didn't need the rest, or could just figure it out for themselves.  

 

This is why, I've tried to break down a process into pieces.  "OK, do this, and let me know when you're done and I'll come back."  Sometimes it works, other times, they either think that means their done, or try and go on their own, and still have issues.  

 

In either case, if the student wants to think of me as the bad guy, that's fine.  I have plenty of other witnesses, who saw me help the student, and heard what I told them to do.  And it is always funny, when I'll have a student blame me for something, only to have one of their classmates chime in, without any word from me, saying "That's not what he told you to do!"


"Anything worth believing, is worth questioning"

#34 Chris Campbell

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Posted 14 July 2014 - 09:44 AM

It is kind of like getting road directions from someone ... you can process the first two or three turns then the brain just goes on vacation.

Once, when lost, we received road directions from a lady on the street ... the lady made us repeat them back to her and would not let us drive off until we had it right.

 

Yep. She was a retired school teacher! :P


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#35 Diesel Clay

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Posted 14 July 2014 - 03:38 PM

I'm not gonna comment on the student/teacher dynamic that seems to be going on here. Sad things happened to your clay work. The rebound off of that can be painful, and learning to deal with the rebound is yet another thing to have to figure out in order to work in any art form. (Many potters have been found in the company of the occasional beer..) I find the discussion about blame allocation to be unhelpful.
In terms of the technical bits, if you don't own a copy of Daniel Rhodes' "Clay and Glazes for the Potter", it can be had for $50 CA used, so I'm sure you can find it cheaper. It was my undergrad glaze and clay text. If your brain box is being twigged by the idea of mixing a clay body, it, or other similar books (suggestions, anyone?) are likely a valuable investment in your six year plan.
There is an awesome thread started by BigLou that details his journey formulating his clay bodies. It lists many good resources.
Using any kind of $(!? mix reclaim is a crap shoot. Are there any suppliers in your area that sell dry bags of their prepared clays? If they do, you might try doctoring one of those to your taste.
I wish you much better luck with the next round!
Cal




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