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#1 Mark McCombs

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Posted 17 November 2012 - 12:55 AM

For the benefit of other beginning potters I would like tooutline a series of mistakes that has put me in a rather awkward and embarrassing situation.

I start potting in June of this year and was sampling various clay bodies to find one that I could move forward with. I have a friend who has done slab work for many years and she offered a bag of her clay for me to try. It turns out, though a bit stiff to get started on the wheel , it finishes well and is real pleasure to trim. This is a very white stone ware that she fires to ^5.5 and ^6 and was developed over several years with her supplier. It is a very good clay body to work with IMO. I split a 2000 pound order with her and started potting. The clay came from the supplier marked withher name and cone 4-6 on the box.

In spite of all that I have read on this board regarding vitrification and testing the clay body maturity, I never once consider this to be an issue with my friend’s clay. The box said 4-6 and she fired to ^6. That was good enough for me.

In October there was a thread about vitrification that I responed to. It was the first time I thought to myself that I should check even though I was sure there was not a problem.

And a week ago, Istarted glazing my 3rd run and added an unglazed cup to the firing( ^6, final temp at 2203F, 5 minute soak, ^7 just starting to move). Imagine my surprise when the cup started leaking water onto the paper in about 5 minutes. What the heck??? Then I thought about checking a cup with glaze on it. I found one that had a small crack in the bottom and “might” have a crack on the inside and it leaked badly. I tested another cup with tiny crack in the bottom and looked good on the inside and it to leaked within 10 minutes or so.

By the way, at this time I am planning my first sale at our town’s annual bazaar three days away. yeah….

I loaded the kiln for the next glaze firing and programed alonger ^6 firing with a final temp at 2232F with a 5 minute soak. I ended upwith a ^7 firing. Again I had placed an unglazed cup in the mix for testing.

After the kiln had cooled to ambient temps, I unloaded andtested the unglazed piece.

It leaked within a half hour. The gravity of the situation was just starting to hit me.

I decided to test a perfectly good, glazed cup from the previous run. It leaked. Right through the glaze, it leaked. So now I am on the phone to the person who developed the glaze and he said that that particular glaze is finicky with certainclay body types and will easily craze. He said to take a permanent marker and colour the bottom of the cup to see the crazing. Sure enough. Crazedlike crazy and I couldn’t see it.

I made a decision to water test all the ware with that glaze. Most all the pieces leaked.

The second glaze load from that run did not have any of thatglaze but another issue was rearing its ugly head. By hitting ^7, I over-fired some other glazes that were developed for ^5-6. Pots were pinging left and right. I thought to myself thatif they craze, they will leak. Sure enough I tested a few bowls and they leaked.

Knowing that none of my pieces were vitrified, I decided to water test my entire inventoryof cups, mugs , bowls and such. The results were extremely disappointing. Istopped counting, but there are more than 75 pieces that are not salable andwhat I was left with would not make a very good display at the bazaar so I hadto cancel my table for tomorrow.

Soooooo….

I have learned a hard lesson or lessons:

· Specifically ask at what cone the particularclay body matures or vitrifies. Use this information as a guide only.

· Run multiple tests (thickness, glazes, cones andfinal temps)on the clay body glazed and unglazed

· Run absorbency and shrinkage test

· Check opaque glazes for crazing with a felt tipmarker

· Specifically ask about glaze compatibility with your clay body

I’m sure there are other lessons and I hope that some of you will point them out.

BTW. My friend who I got the clay from has a well-developed glaze that fits her clay body at^6. She does not make functional pottery but has made ichibanas that do not leak for several years.

The glazes I use to not fit that clay body and I have noidea at what cone it vitrifies at.

A new search begins.


Mark
Fast Hawk Pottery


^5-6 Ox
1227 Skutt

#2 oldlady

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Posted 17 November 2012 - 01:09 AM

i am sorry that this happened to you. please read the posts on food safety and the discussion there. it is enough to make someone decide to make only tiny figurines or huge sculptures and never try another bowl or mug.

at least you learned early. i know a person who keeps making leaking mugs and has just shrugged it off.

(Yes i DO want to kick her.)

keep on trying. i've been at it 40 years and am a rank amateur............but something keeps dragging me out to the studio............................
"putting you down does not raise me up."

#3 Mark McCombs

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Posted 17 November 2012 - 01:45 AM

i am sorry that this happened to you. please read the posts on food safety and the discussion there. it is enough to make someone decide to make only tiny figurines or huge sculptures and never try another bowl or mug.


Yes. I have read that thread. Good stuff there. B)src="http://ceramicartsda...ault/cool.gif">


I will still make pottery for every day use. I feel quite strongly about that.


:)src="http://ceramicartsda...ult/smile.gif">
Mark
Fast Hawk Pottery


^5-6 Ox
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#4 Chris Campbell

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Posted 17 November 2012 - 09:26 AM

So sorry for you!!
Unfortunately or fortunately if we are smart ... we all learn more from our failures than we do from success. Don't feel lonely though ... I am fairly sure almost everyone here has a nightmare story where they were the central character and flaw. :)

Chris Campbell
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TRY ...   FAIL ...  LEARN ...  REPEAT


#5 OffCenter

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Posted 17 November 2012 - 10:10 AM

So sorry, Mark, to hear about your misfortune. I would have a conversation with the company that made the clay and stamped cone 4-6 on the box and take legal action if necessary. As hard as it is to believe, many potters would not have ever bothered to test for leakage and some would have sold the pots even after discovering they leaked. I know it is too small of an industry and none of us really want it, but I wish there was some government agency that did nothing but go to craft shows and test pottery for leaks and unstable glazes so that potters who give all potters a bad name by selling leaking pot and pots with unsafe glazes would be fined out of business.

Jim
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#6 JBaymore

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Posted 17 November 2012 - 11:22 AM

I would have a conversation with the company that made the clay and stamped cone 4-6 on the box and take legal action if necessary.


Mark,

As you know I already privately suggested that you look into this idea. But you took all the blame right onto yourself in the answer you gave me....... which is admirable....... but maybe it is not necessarily ALL "your fault".

I'm with Jim on this one now that I know that the clay was labeled by a manufacturer as a cone 4-6 product and it is THIS far off. Did they publish Apparent Porosity ("absorbtion") figures for this clay anywhere... and is it meeting them?

My one question however is if you friend makes SCULPTURE and you are making functional pots, is the body labeled as a SCULPTURE clay body by the supplier? If so........ they can argue (quite rightly) that it was never intended to be used for making pots, and that the issue of being vitreous has been traded off for properties that a sculptor might want for certain types of work. It is possibe for a sculptor to be perfectly happy with a non-vitrified body. (For outdoor use .....no.... but that is another can o' worms.)

If you bought a car and they said it had a V-6 engine in it, and you paid for that engine, and later you found out it actually only had a 4 cylinder engine in it...... well.... you get the idea. At the LEAST as a PROFESSIONAL operation they should be refunding you the money spent on the clay with them. Sounds like maybe a bad batch.... or a poor original formulation. That is likely all that they would ever do.

I would guess that somewhere in their product literature or on the website they are going to have published a statement that basically says they are not responsible for anything and that it is the responsibility of the end user to test the applicability of any raw material to the final intended use. That is the "dodge" most clay companies use to get out from under quality control issues.

And it is true that we should be testing new stuff before putting it into full production. If nothing else than to protect ourselves from experienceing just this kind of thing.

If they are uncoopertative, this might be the kind of thing a small claims court would handle. No lawyer expenses.... just you and them and a Judge and the story. I've been there on this issue in the past and got the materials paid for (meaning I did not have to pay the clay bill.)

I said it on Facebook and I'll say it again here......... GOOD ON YA' for accepting the hit and taking the pieces out of the potential sales venue. As I said there on Facebook and others have said here... there are some that would just sell the stuff anyway. Your actions show integrity and character. THANK YOU on behalf of the whole pottery community for helping to protect the reputation of handcrafted ceramics with the general public. And for so openly sharing your story here on the Forum so that others can learn from it also.

Sorry you had to pay some tuition to the "School of Hard Knocks".

best,

........................john
John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

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#7 JBaymore

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Posted 17 November 2012 - 11:35 AM

Don't feel lonely though ... I am fairly sure almost everyone here has a nightmare story where they were the central character and flaw. :)src="http://ceramicartsda...ult/smile.gif">



A long, long time ago in a galaxy far, far away......... I failed to test a large new order of my custom formula clay body (from a supplier that no longer exists....wonder why B)src="http://ceramicartsda...ault/cool.gif"> ) before putting it into full production. There were some "warning signs" that I caught early on in working with it that there might be some issue...... but I (unfortunately and stupidly) relied on the verbal answers and assurances which I got to the questions I asked the supplier instead of taking some samples to a full "finish fired" state before committing to the clay batch.

I then unloaded my whole noborigama (wood fired climbing kiln) load directly into my shard pit. 2 months + of full time 60 hour + weeks work, all of the invested materials like clay and glaze and wadding and cords of wood, and the ORDERS that were in that load. I lost a couple of good clients over that one....................you don't recover well from things like not having the 12 place dinnerware set for the bride and groom ready on time.

It almost bankrupted my business. Back then I did not have much "cushion" to absorb that kind of direct financial loss or even the interuption in cash flow.

So yes Chris........ we've likely all "paid some dues". You are not alone Mark, you are not alone.

best,

.........................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

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#8 Mark McCombs

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Posted 17 November 2012 - 12:19 PM

Thank you for the replies.


Perhaps I should point out that the clay body was/is not intended for sale to anybody other than the artist who designed it.
In fact she was the one who put in the order and I just bought half of it from her.

The manufacturer had no idea I was getting the clay body.



:)src="http://ceramicartsda...ult/smile.gif">
Mark
Fast Hawk Pottery


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#9 TJR

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Posted 17 November 2012 - 05:38 PM

Thank you for the replies.


Perhaps I should point out that the clay body was/is not intended for sale to anybody other than the artist who designed it.
In fact she was the one who put in the order and I just bought half of it from her.

The manufacturer had no idea I was getting the clay body.



:)src="http://ceramicartsda...ult/smile.gif">


Mark;
There are some salient points in your own response. Could you sell your half of the clay order back to her at an attractive discount? Sometimes we just have to wash our hands of the problem, get a new clay batch and move on. This time of year, there is a lot of pressure to have "product" out there, but if you are not happy with the clay and can't stand behind your work, move past it. You have had a misunderstanding with your sculptor friend. I hope you can still be friends.We have all made some great boo boos. Go eat some turkey.
Tom TJR.

#10 Mark McCombs

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Posted 17 November 2012 - 05:58 PM

Yep.

Most of the misunderstanding came from me not asking the right questions and waiting for the proper responses.

No issue with my friend. She has offered to buy back the clay body. (which I will do)

I am on the hunt for another white clay body that matures at ^6.

mmmmmm... Turkey.....
Mark
Fast Hawk Pottery


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#11 Mark C.

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Posted 18 November 2012 - 01:08 AM

Mark
You have learned a bunch from this and are moving on which is all you can do

As this body was a custom made for another who is happy with it . Glad she is buying it back.
I will add that you have taken the high road and I'm glad you did.
I will add in all my years of production pottery there is nothing worse than body problems as they are the heart of what we do-yes we can change glazes but if the body is questionable then its usually catastrophic by the time we figure it out. Sorry it happened just now but anytime is bad really.
The only thing worse than leaky pots is ones that come apart after the glaze fire (dunting or shivering) but its all bad.

Mark
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#12 Pres

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Posted 21 November 2012 - 09:48 PM

For the benefit of other beginning potters I would like tooutline a series of mistakes that has put me in a rather awkward and embarrassing situation.

I start potting in June of this year and was sampling various clay bodies to find one that I could move forward with. I have a friend who has done slab work for many years and she offered a bag of her clay for me to try. It turns out, though a bit stiff to get started on the wheel , it finishes well and is real pleasure to trim. This is a very white stone ware that she fires to ^5.5 and ^6 and was developed over several years with her supplier. It is a very good clay body to work with IMO. I split a 2000 pound order with her and started potting. The clay came from the supplier marked withher name and cone 4-6 on the box.

In spite of all that I have read on this board regarding vitrification and testing the clay body maturity, I never once consider this to be an issue with my friend’s clay. The box said 4-6 and she fired to ^6. That was good enough for me.

In October there was a thread about vitrification that I responed to. It was the first time I thought to myself that I should check even though I was sure there was not a problem.

And a week ago, Istarted glazing my 3rd run and added an unglazed cup to the firing( ^6, final temp at 2203F, 5 minute soak, ^7 just starting to move). Imagine my surprise when the cup started leaking water onto the paper in about 5 minutes. What the heck??? Then I thought about checking a cup with glaze on it. I found one that had a small crack in the bottom and “might” have a crack on the inside and it leaked badly. I tested another cup with tiny crack in the bottom and looked good on the inside and it to leaked within 10 minutes or so.

By the way, at this time I am planning my first sale at our town’s annual bazaar three days away. yeah….

I loaded the kiln for the next glaze firing and programed alonger ^6 firing with a final temp at 2232F with a 5 minute soak. I ended upwith a ^7 firing. Again I had placed an unglazed cup in the mix for testing.

After the kiln had cooled to ambient temps, I unloaded andtested the unglazed piece.

It leaked within a half hour. The gravity of the situation was just starting to hit me.

I decided to test a perfectly good, glazed cup from the previous run. It leaked. Right through the glaze, it leaked. So now I am on the phone to the person who developed the glaze and he said that that particular glaze is finicky with certainclay body types and will easily craze. He said to take a permanent marker and colour the bottom of the cup to see the crazing. Sure enough. Crazedlike crazy and I couldn’t see it.

I made a decision to water test all the ware with that glaze. Most all the pieces leaked.

The second glaze load from that run did not have any of thatglaze but another issue was rearing its ugly head. By hitting ^7, I over-fired some other glazes that were developed for ^5-6. Pots were pinging left and right. I thought to myself thatif they craze, they will leak. Sure enough I tested a few bowls and they leaked.

Knowing that none of my pieces were vitrified, I decided to water test my entire inventoryof cups, mugs , bowls and such. The results were extremely disappointing. Istopped counting, but there are more than 75 pieces that are not salable andwhat I was left with would not make a very good display at the bazaar so I hadto cancel my table for tomorrow.

Soooooo….

I have learned a hard lesson or lessons:

· Specifically ask at what cone the particularclay body matures or vitrifies. Use this information as a guide only.

· Run multiple tests (thickness, glazes, cones andfinal temps)on the clay body glazed and unglazed

· Run absorbency and shrinkage test

· Check opaque glazes for crazing with a felt tipmarker

· Specifically ask about glaze compatibility with your clay body

I’m sure there are other lessons and I hope that some of you will point them out.

BTW. My friend who I got the clay from has a well-developed glaze that fits her clay body at^6. She does not make functional pottery but has made ichibanas that do not leak for several years.

The glazes I use to not fit that clay body and I have noidea at what cone it vitrifies at.

A new search begins.





I am sorry to hear about your problem with the clay. It is one of those things that often a small thing that one should be able to count on is overlooked. Years ago, I struggled an entire summer with watercolor while taking a class. My colors turned out dull, looked bright on palette, but dried on paper dull and lifeless. I tried different paints, different papers, experimented with inks and all sorts of color agents looking for the brightness I used to have with color. Then one day while on trip used bottled water as I was not near the tap. Voila. When I returned home, I had the tap water tested. Basically it had a range of chemicals that dulled the paint. Now I only use bottled or distilled water. Simple thing, easily overlooked, because we depend on it to be normal. Not your fault.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#13 Marcia Selsor

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Posted 22 November 2012 - 07:40 AM

I am sorry to hear about your experience but it is a valuable learning experience . Thank you with sharing it with everyone. The clay body was developed foe slab work, I am assuming sculptural work not needing a glaze. Now you understand that clay bodies are designed for specific purposes. I am glad you can sell it back to the designer of the clay body...unfortunately after you have lost so much work. Move on and know you have gained a good education. You probably will be able to throw better with a nice throwing body. I expect to hear that your forms grow by leaps and bounds.

Marcia








#14 Kabe

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Posted 25 November 2012 - 10:33 PM

Yep.

Most of the misunderstanding came from me not asking the right questions and waiting for the proper responses.

No issue with my friend. She has offered to buy back the clay body. (which I will do)

I am on the hunt for another white clay body that matures at ^6.

mmmmmm... Turkey.....



Julia Gallaway has a website that has some cone 6 white claybody's on it. I have made up a small batch of one of them, but I haven't ran any tests on it. might take a look there. Happy firing




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