Ron Roy on mon 4 nov 02
Just a few remarks and an endorsement of the comments by Michael and John
on clay.
It is no use to think you can make a better clay body than buying it -
unless you follow a few basic rules. Don't assume the material you get is
the same as last time - not even from the same skid. Test your materials
until you have some idea of which are stable - and even then - test your
raw materials.
Making a clay body - or lifting one from anywhere - does not guarantee
anything. You need to test it and try your glazes on it - not just little
test tiles - remember - fit problems are magnified by the size of the ware.
You must screen all materials that go into a clay body through 30 mesh - or
as Michael suggests - sieve the body wet - through 30 mesh. There is no
other way to protect against unwanted chunks - the 30 mesh sieve will also
take out any calcium that may result in lime pops.
The idea that you don't have to test a body you make yourself is false -
you are using the same basic material that the clay makers use.
Accumulated data over the years will be your best friend - look at it every
time you add to it - if something goes wrong you will have the answer at
hand.
Or - know the way to the land fill - you are going to go there eventually.
RR
From: Michael Wendt
A general principle that saves you heartache is: always order ahead. Order
and test a new batch of clay WHILE you still have enough of the previous
batch to keep working. Test samples from throughout the new batch you
receive. If you wait until you are out and then make pots to sell from the
new batch that are no good, you will really suffer.
>Now in defense of the suppliers........... in many cases it is the potter's
>own fault for not having much of a technical background and not doing
>appropriate testing BEFORE putting materials to use. It doesn't take much
>effort to make one pot out of the new batch of clay and fire it, or to make
>a 500 gram batch of the glaze and fire it before making 30,000 grams of it.
> Ceramics is a VERY technical field underlying the art part. Too many
>don't have that piece of the puzzle.... and then wonder why they have
>problems.
From: John Baymore
>But now in defense of the potter........... at some level...... when you
>buy a new car...... you expect it to stop when you step on the brakes. You
>shouldn't have to hire a mechanic to take off the wheels and check the
>brakes before you drive it out of the showroom. Blended clay bodies
>shouldn't be ALL that much different.
>
>And all too many times, in my experience talking with potters all over and
>in doing consulting work, the problems potters get CLEARLY should have
>been caught by the supplier's or the manufactrurer's QC program. Even when
>the supplier takes the material back and replaces it........... any lost
>time incurred by the potter waiting for the thing to get straightened out
>is not ususally considered. Nor the "ulcers". And if it is straightened
>out AFTER work has been produced..... it just about NEVER takes into
>consideration the lost revenues.
>
>When confronted by such situations, the suppliers typically just say "run
>of mine ....we're not responsible.... you don't know what you are doing....
>see the liability statement in our catalog."
>
>In too many cases it is total crap.
>
>And they can bet pretty safely that a person earning less than minimum wage
>for their working time is not going to be hiring a lawyer at $150 an hour
>to "win" a case that invloves only say.......$1000 of product...... and
>incur maybe a $5000 legal bill to do it.
>
>Again a bit in the suppliers defense........ it seems that most potters are
>totally "price based" in their buying decisions. So manufacturers and
>suppliers have little margin to play with for the fund things like better
>testing and QC programs and in being able to "eat" a big problem. They
>have to keep the price as low as possible to keep customers.
>
>
>I think this whole area TOO is a place the Potter's Council could have some
>positive impact. How about a "QC Approval" program....... an endorsement.
>Along the ISO 9000 idea.....but not as involved. The Council sets up the
>exact guidelines that a manufacturer has to meet....and if they do.......
>they get the PC stamp of approval. The stamp of approval lets potters know
>a bit about the reliability of the company's products..... and the way they
>will be treated if a problem occurs. That could help a LOT.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
KLeSueur@AOL.COM on tue 5 nov 02
Clay companies care about the quality of their materials in relation to the needs of their largest customers. The steel industry, one of the largest comsumers of clay, could care less about lime contamination. It has no effect on their product. Show me a brick house and I'll show you lime pop outs. Show me a stack of flue liners at a construction supplier and I'll show you lime pop outs.
On the other hand, AC spark plug is the biggest user of EPK Kaolin. They have very strict requirements for the clay they use. As a result you can count on EPK being clean and consistant.
The percentage of clay used by potters is so small in the aggragate that we have no voice when it comes to quality. Therefore, we must take special care when it comes to our materials. Screeening is a must. Testing is a must. And buying from a supplier that takes care in what they carrying even though the price might be a little higher is also a must.
Kathi LeSueur
Michael Wendt on tue 5 nov 02
Ron,
Thanks for mentioning that point you made about the need to test the
incoming raw materials. The reason this hits home to me is that I just got a
big complaint from a clay retailer. They bought 5 tons of 10 mesh Helmer,
mixed a porcelain with it and then had angry customers complaining about all
the chunks and grit in the clay. The 10 mesh grind is only intended for the
slurry method but they wanted to save money by not paying for airfloat. I
didn't mention this on Clayart because it is not my intent to harm anyone,
but it drives home a point:
A potter who merely grabs bags of materials and throws them together without
testing will no doubt find he has jumped out of the frying pan and into the
fire because he will not even have anyone else to go back to or blame except
himself. At least when you buy from a reputable dealer, you have some
recourse for recovery, but you also place your trust in his wisdom to choose
appropriate materials for the job.
Regards,
Michael Wendt wendtpot@lewiston.com
Wendt Pottery
2729 Clearwater Avenue
Lewiston, Idaho 83501
1-208-746-3724
wendtpottery.com
Ron Roy wrote:
Just a few remarks and an endorsement of the comments by Michael and John
on clay.
It is no use to think you can make a better clay body than buying it -
unless you follow a few basic rules. Don't assume the material you get is
the same as last time - not even from the same skid. Test your materials
until you have some idea of which are stable - and even then - test your
raw materials.
Making a clay body - or lifting one from anywhere - does not guarantee
anything. You need to test it and try your glazes on it - not just little
test tiles - remember - fit problems are magnified by the size of the ware.
You must screen all materials that go into a clay body through 30 mesh - or
as Michael suggests - sieve the body wet - through 30 mesh. There is no
other way to protect against unwanted chunks - the 30 mesh sieve will also
take out any calcium that may result in lime pops.
The idea that you don't have to test a body you make yourself is false -
you are using the same basic material that the clay makers use.
Accumulated data over the years will be your best friend - look at it every
time you add to it - if something goes wrong you will have the answer at
hand.
Or - know the way to the land fill - you are going to go there eventually.
RR
John Britt on tue 5 nov 02
Kathi,
I am not sure but I think that the paper industry has over taken the spark
plug industry as the largest user of kaolin?
John Britt
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