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ancient potters, aging clay

updated tue 10 apr 07

 

Bryan Johnson on wed 28 mar 07


Matthew Katz wrote:
> The fact
> is that that by slaking down you clay you are putting it in a slurry
> state,
> and aiding in throughly mixing the clay which was not accomplished in the
> first place. Where as the traditional mixing methods (Soldner, Muller,
> and
> Dough Mixers) Do a poor job of properly mixing the clay form the
> start. By
> braking the clay down and getting it mixed up really well in a slurry,
> you
> will improve you performance dramatically.
> -snip-
> Matt
>

Since I have a Soldner mixer and a de-airing pug mill how can I use
these tools most effectively,
particularly when I am not mixing reclaim as part of the mix?



Bryan Johnson

Lili Krakowski on wed 28 mar 07


well, this is typed left handed as I had my 4th carpal tunnel surgery, right
hand, yesterday. Feeling fine.

As to myth and aging clay. I thought Bill's exposition fascinating, clear
and precise. Which does not alter my conviction that my recycled clay works
better than "out of the box" clay. It may be that my belief in the "myth"
makes it happen, it may be that ions improve over eons, it may be that,
despite my using a pug mill. and the clay body manufacturer using the latest
up to date equipment, the mix nevertheless still improves from being worked.
Myth is powerful! Maybe my belief makes it happen.

The proposed theory does not change the perception that clay that has been
around a while works better than new. It well may be that bacteria have
nothing to do with it, that it is congruence,and that while the ions are
scurrying around, and changes in moisture and or temp are making the
particles snuggle together more cozily, the bacteria have taken all the
credit!

There is of course this possibility. That the ancient Chinese did not have
the refined super clean clay we have today. So when they buried the clay for
their grandchildren, there were a few small rodents, a few leaves, some
unmentionable animal products, some grass in there,which, over time, thanks
to bacteria, decomposed. Once that stuff was gone, the clay should work
better.

(But between Great-Aunt L and all the grandparents out there-- the
difference came from the young potters knowing how much their grandparents
cared for them, and for the craft!)

















Lili Krakowski
Be of good courage

Bob Hanlin on wed 28 mar 07


Wow...I agree with a guru!!!!!!!!!!!!

Bob


----- Original Message ----
From: Lili Krakowski
To: CLAYART@LSV.CERAMICS.ORG
Sent: Wednesday, March 28, 2007 10:42:29 AM
Subject: ancient potters, aging clay


well, this is typed left handed as I had my 4th carpal tunnel surgery, right
hand, yesterday. Feeling fine.

As to myth and aging clay. I thought Bill's exposition fascinating, clear
and precise. Which does not alter my conviction that my recycled clay works
better than "out of the box" clay. It may be that my belief in the "myth"
makes it happen, it may be that ions improve over eons, it may be that,
despite my using a pug mill. and the clay body manufacturer using the latest
up to date equipment, the mix nevertheless still improves from being worked.
Myth is powerful! Maybe my belief makes it happen.

The proposed theory does not change the perception that clay that has been
around a while works better than new. It well may be that bacteria have
nothing to do with it, that it is congruence,and that while the ions are
scurrying around, and changes in moisture and or temp are making the
particles snuggle together more cozily, the bacteria have taken all the
credit!

There is of course this possibility. That the ancient Chinese did not have
the refined super clean clay we have today. So when they buried the clay for
their grandchildren, there were a few small rodents, a few leaves, some
unmentionable animal products, some grass in there,which, over time, thanks
to bacteria, decomposed. Once that stuff was gone, the clay should work
better.

(But between Great-Aunt L and all the grandparents out there-- the
difference came from the young potters knowing how much their grandparents
cared for them, and for the craft!)

















Lili Krakowski
Be of good courage

______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

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Matthew Katz on wed 28 mar 07


Sorry to sound like a broken record, but...
I stole this from one of my own previous posts.
-snip-
I think that there is a step in the process that might have been overlooked.
There is an assumption that in slop clay the aging of the slop is what it
made it better. I would argue that it is in fact the slaking of the clay
body that enhance the performance. For those who did see our presentations
at NCECA, you will note that the vast majority of of conversation was about
proper mixing (50%) vs aging ( 0.01%), and how Slurry mixing, is by leaps
and bound the best way to improve clay performance on all fronts. The fact
is that that by slaking down you clay you are putting it in a slurry state,
and aiding in throughly mixing the clay which was not accomplished in the
first place. Where as the traditional mixing methods (Soldner, Muller, and
Dough Mixers) Do a poor job of properly mixing the clay form the start. By
braking the clay down and getting it mixed up really well in a slurry, you
will improve you performance dramatically.
-snip-
Matt

On 3/28/07, Bob Hanlin wrote:
>
> Wow...I agree with a guru!!!!!!!!!!!!
>
> Bob
>
>
> ----- Original Message ----
> From: Lili Krakowski
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Wednesday, March 28, 2007 10:42:29 AM
> Subject: ancient potters, aging clay
>
>
> well, this is typed left handed as I had my 4th carpal tunnel surgery,
> right
> hand, yesterday. Feeling fine.
>
> As to myth and aging clay. I thought Bill's exposition fascinating,
> clear
> and precise. Which does not alter my conviction that my recycled clay
> works
> better than "out of the box" clay. It may be that my belief in the "myth"
> makes it happen, it may be that ions improve over eons, it may be that,
> despite my using a pug mill. and the clay body manufacturer using the
> latest
> up to date equipment, the mix nevertheless still improves from being
> worked.
> Myth is powerful! Maybe my belief makes it happen.
>
> The proposed theory does not change the perception that clay that has been
> around a while works better than new. It well may be that bacteria have
> nothing to do with it, that it is congruence,and that while the ions are
> scurrying around, and changes in moisture and or temp are making the
> particles snuggle together more cozily, the bacteria have taken all the
> credit!
>
> There is of course this possibility. That the ancient Chinese did not
> have
> the refined super clean clay we have today. So when they buried the clay
> for
> their grandchildren, there were a few small rodents, a few leaves, some
> unmentionable animal products, some grass in there,which, over time,
> thanks
> to bacteria, decomposed. Once that stuff was gone, the clay should work
> better.
>
> (But between Great-Aunt L and all the grandparents out there-- the
> difference came from the young potters knowing how much their grandparents
> cared for them, and for the craft!)
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Lili Krakowski
> Be of good courage
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

Hank Murrow on wed 28 mar 07


>
> ----- Original Message ----
> From: Lili Krakowski
>
> There is of course this possibility. That the ancient Chinese did
> not have
> the refined super clean clay we have today. So when they buried the
> clay for
> their grandchildren, there were a few small rodents, a few leaves,
> some
> unmentionable animal products, some grass in there,which, over
> time, thanks
> to bacteria, decomposed. Once that stuff was gone, the clay
> should work
> better.

Hank Murrow replies;

Last Summer I visited a potter in Tokyo who had a friend in the
construction business. His friend was in charge of excavation near
Tajimi in preparation of the building of a golf course. The potter
went down to the golf course site with gis friend to scope out the
clay they were excavating. He wound up getting 13 tons of excellent
Mogusa clay for making Tea ware(shino and hikidashi setoguro). In his
brand new studio he had lead lined boxes constructed under the floor
with hatches that can be removed. There is where the clay waits for
him...........a lifetime's supply for a maker of chawan. I posted a
pic of his ware at:

http://www.flickr.com/photos/claycraft/

Cheers, Hank
www.murrow.biz/hank

William & Susan Schran User on thu 29 mar 07


On 3/28/07 9:38 PM, "Matthew Katz" wrote:

> The fact
> is that that by slaking down you clay you are putting it in a slurry state,
> and aiding in throughly mixing the clay which was not accomplished in the
> first place. Where as the traditional mixing methods (Soldner, Muller, and
> Dough Mixers) Do a poor job of properly mixing the clay form the start. By
> braking the clay down and getting it mixed up really well in a slurry, you
> will improve you performance dramatically.

I have no doubt what you write is true because I have observed this in my
more than 30 years with clay. But can we put our finger on what it is about
the slaking/mixing process that make one better than the other?

I don't have an answer, but my observations lead me to some thoughts.

The slurry buckets stink (a good stink!), so there must be some type of
organic process going on.
My thoughts would conclude it's the organic materials in the clay, but the
stink is not in the prepared bag of moist clay.
So now I conclude it must be skin and hair from me (in my studio) and my
students (at school). This is even more pronounced during the summer raku
class when the coarser clay will abrade more skin from the hands.

Do these organic materials change the chemistry of the clay?
Do they change the pH of the clay?
Or is it simply that the slurry aids in wetting the clay more completely and
faster than just adding water?

--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com

WJ Seidl on thu 29 mar 07


Question for the group:
I got a brief glimpse these past two NCECAs at the Soldner mixer.
It appears to be based on a rotating concrete drum.
Does this drum not hold water?
Would we not be able to blunge (albeit slowly) clay materials to a slurry in
it, and simply allow the moisture to evaporate, or would that take
excessively long?

Failing that...does anyone have plans for a smaller filter press?

Best,
Wayne Seidl

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bryan Johnson
Sent: Wednesday, March 28, 2007 11:16 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: ancient potters, aging clay

Matthew Katz wrote:
> The fact
> is that that by slaking down you clay you are putting it in a slurry
> state,
> and aiding in throughly mixing the clay which was not accomplished in the
> first place. Where as the traditional mixing methods (Soldner, Muller,
> and
> Dough Mixers) Do a poor job of properly mixing the clay form the
> start. By
> braking the clay down and getting it mixed up really well in a slurry,
> you
> will improve you performance dramatically.
> -snip-
> Matt
>

Since I have a Soldner mixer and a de-airing pug mill how can I use
these tools most effectively,
particularly when I am not mixing reclaim as part of the mix?



Bryan Johnson

____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Hank Murrow on thu 29 mar 07


On Mar 29, 2007, at 5:42 AM, WJ Seidl wrote:

> Question for the group:
> I got a brief glimpse these past two NCECAs at the Soldner mixer.
> It appears to be based on a rotating concrete drum.
> Does this drum not hold water?
> Would we not be able to blunge (albeit slowly) clay materials to a
> slurry in
> it, and simply allow the moisture to evaporate, or would that take
> excessively long?

Dear Wayne;

I have had a Soldner Pro mixer for the past 33 years, and I found it
a fast way to mix pretty terrible clay. It takes months of aging and
a either a pugmill or lots of wedging to bring it around to really
plastic condition for throwing. You cannot mix in it the way you
suggest, as the clay must be mixed at plastic condition for it to
pull away from the tub. I have not used the machine for years.

When I mix clay, I blunge around 300 dry #s of my recipe with enough
water to make a 'milk shake' in a large redwood tank with a
'Lightning' mixer, and run the slurry from a tap in the botom through
a homemade vibrating screen(I have replaceable stainless screens from
30 mesh to 80 mesh), into buckets which I pour out into 2x6 frames
with hardware cloth bottoms. The frames are loaded with polyester
canvas that is folded over the slurry to keep critters and leave out.
The clay dries to plastic condition in 3_6 days, (depending on the
weather) in my solarium/showroom. Wedge or pug and place in double
bags............ you can pull handles immediately with this super-
plastic clay.

if one lives in a real cold climate, the slurry may be set out in the
frames in the canvas where it will freeze. Ice stalagtites will be
squeezed out of the slurry, where they can be brushed off, the frozen
clay brought in to thaw, and voila........... plastic clay.

The process is pretty quiet too.

Cheers, Hank in Eugene, where Spring Rules

www.murrow.biz/hank

Thomas Malone on thu 29 mar 07


Hello Matt.

=93Where as the traditional mixing methods (Soldner, Muller, and Dough
Mixers) Do a poor job of properly mixing the clay form the start. By
braking the clay down and getting it mixed up really well in a slurry, you
will improve you performance dramatically.=94

This is music to my ears! I would only negatively comment about your
description of dry mixing being =93traditional mixing methods =94 as wet mix=
ing
is not only traditional in many parts of the world but are also the modern
methods. Whereas, in my experience, dry mixing is only common in heavy
clays (bricks etc) and the USA. Wet methods, such as mixing by blunger +
ark or by ball mills, are very widely used and long recognised as being
much better at producing hiomogeneous mixes, wetting all the raw material
particles and maximising the making properties. Thank you for high lighting
this.

Paul Herman on thu 29 mar 07


Hi Wayne,

I think you could use a Soldner mixer for blunging slip, but if you
want to dry it in the tub by evaporation it will tie up the mixer for
a while.

I wish filter presses were more readily available to studio potters
(read cheap).

Harry Davis' book "The Potter's Companion" has plans for a vacuum
operated filter dewaterer that you can build at home. It looks like a
lot of work to put together. Has anyone on the list ever built one of
these?

You can always dry slurry in trays or old levi pant legs, but you've
got to be there at the right time to bag up the clay. When I want to
dry a batch of slip, I use a wooden tray with a hardware cloth
bottom, lined with an old sheet. It takes from a few days to a week
to get to then right consistency, depending on the weather.

Matt and Bill, welcome to clayart. I think the discussion you guys
have started here is great. After reading your posts on thorough
wetting of clay particles, I have to agree with you. Thanks for the
discussion.

Paul Herman

Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com


On Mar 29, 2007, at 4:42 AM, WJ Seidl wrote:

> Question for the group:
> I got a brief glimpse these past two NCECAs at the Soldner mixer.
> It appears to be based on a rotating concrete drum.
> Does this drum not hold water?
> Would we not be able to blunge (albeit slowly) clay materials to a
> slurry in
> it, and simply allow the moisture to evaporate, or would that take
> excessively long?
>
> Failing that...does anyone have plans for a smaller filter press?
>
> Best,
> Wayne Seidl
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bryan
> Johnson
> Sent: Wednesday, March 28, 2007 11:16 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: ancient potters, aging clay
>
> Matthew Katz wrote:
>
>> The fact
>> is that that by slaking down you clay you are putting it in a slurry
>> state,
>> and aiding in throughly mixing the clay which was not accomplished
>> in the
>> first place. Where as the traditional mixing methods (Soldner,
>> Muller,
>> and
>> Dough Mixers) Do a poor job of properly mixing the clay form the
>> start. By
>> braking the clay down and getting it mixed up really well in a
>> slurry,
>> you
>> will improve you performance dramatically.
>> -snip-
>> Matt
>>
>>
>
> Since I have a Soldner mixer and a de-airing pug mill how can I use
> these tools most effectively,
> particularly when I am not mixing reclaim as part of the mix?
>
>
>
> Bryan Johnson
>
> ______________________________________________________________________
> ______
> __
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>

Matthew Katz on thu 29 mar 07


Hi Wayne
2 problems, when we talk about slurry mixing we are talking abut speeds that
the solders don't match (x1500 RPM we use Shar mixers), But A heavy duty
drill and a pint mixing blade along with a big bucket would do the trick.
The second is drying and extraction, it would really difficult to get 20
gallons of slip out of that thing. We use a filterpress, but a large plaster
drying slab would work ok in the normal studio, Just make sure to tend to
the clay as it is drying.

On 3/29/07, WJ Seidl wrote:
>
> Question for the group:
> I got a brief glimpse these past two NCECAs at the Soldner mixer.
> It appears to be based on a rotating concrete drum.
> Does this drum not hold water?
> Would we not be able to blunge (albeit slowly) clay materials to a slurry
> in
> it, and simply allow the moisture to evaporate, or would that take
> excessively long?
>
> Failing that...does anyone have plans for a smaller filter press?
>
> Best,
> Wayne Seidl
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bryan Johnson
> Sent: Wednesday, March 28, 2007 11:16 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: ancient potters, aging clay
>
> Matthew Katz wrote:
> > The fact
> > is that that by slaking down you clay you are putting it in a slurry
> > state,
> > and aiding in throughly mixing the clay which was not accomplished in
> the
> > first place. Where as the traditional mixing methods (Soldner, Muller,
> > and
> > Dough Mixers) Do a poor job of properly mixing the clay form the
> > start. By
> > braking the clay down and getting it mixed up really well in a slurry,
> > you
> > will improve you performance dramatically.
> > -snip-
> > Matt
> >
>
> Since I have a Soldner mixer and a de-airing pug mill how can I use
> these tools most effectively,
> particularly when I am not mixing reclaim as part of the mix?
>
>
>
> Bryan Johnson
>
>
> ____________________________________________________________________________
> __
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

Matthew Katz on thu 29 mar 07


You are assuming that because bacteria grows, that it must have something to
do with the performance of the clay. That is sort of like assuming that
because you saw a Polar Bear at the Bronx Zoo that Polar Bears must be
native to New York.
We have proven that without a doubt that Mixing is the MOST important factor
in the performance of all clays. and the only way to mix with complete
effectiveness is in the slurry.
matt

On 3/29/07, William & Susan Schran User wrote:
>
> On 3/28/07 9:38 PM, "Matthew Katz" wrote:
>
> > The fact
> > is that that by slaking down you clay you are putting it in a slurry
> state,
> > and aiding in throughly mixing the clay which was not accomplished in
> the
> > first place. Where as the traditional mixing methods (Soldner, Muller,
> and
> > Dough Mixers) Do a poor job of properly mixing the clay form the start.
> By
> > braking the clay down and getting it mixed up really well in a slurry,
> you
> > will improve you performance dramatically.
>
> I have no doubt what you write is true because I have observed this in my
> more than 30 years with clay. But can we put our finger on what it is
> about
> the slaking/mixing process that make one better than the other?
>
> I don't have an answer, but my observations lead me to some thoughts.
>
> The slurry buckets stink (a good stink!), so there must be some type of
> organic process going on.
> My thoughts would conclude it's the organic materials in the clay, but the
> stink is not in the prepared bag of moist clay.
> So now I conclude it must be skin and hair from me (in my studio) and my
> students (at school). This is even more pronounced during the summer raku
> class when the coarser clay will abrade more skin from the hands.
>
> Do these organic materials change the chemistry of the clay?
> Do they change the pH of the clay?
> Or is it simply that the slurry aids in wetting the clay more completely
> and
> faster than just adding water?
>
> --
> William "Bill" Schran
> wschran@cox.net
> wschran@nvcc.edu
> http://www.creativecreekartisans.com
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

Michael Wendt on thu 29 mar 07


I can suggest an experiment to
decide how much organics
contribute to clay aging and
plastic behavior.
One of our commercial clay
customers buys clay for the
retail market and the stores
they sell to require the addition
of a biocide to prevent mold
and bacterial growth.
This biocide: Nuosept 95
is lab tested and approved
by the Art and Craft Materials
Institute as a skin safe material
that can be used in things like
finger paint and clay.
Why not try it in some clay
done by various means?
Make a control batch without.
Make an identical batch with
Test forming character at regular
time intervals.
To work, it must be added to
the water and then mixed, so
it could also be used to test
recycling clay.
To be a fair test here, all slop
and trims would need to be
dried first. Then split into two
equal weight piles and the
sane amount of water added to
both ( with one containing Nuosept).
The final part of the puzzle would
be to have someone other than you
sample the two bodies without
prior knowledge of which is
which. If there were a color or
smell difference, they would both
need to be controlled for by blind-
fold and /or nose plugs.
For best test reliability, several testers
would be preferable.
Thoughts?
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com

Matthew Katz on thu 29 mar 07


True,
I only speak of "traditional" as the method used by clay manufactures, and
studio potters who have that particular equipment.
We work "All Slurry All the Time" in my research group, and advocate it as
the standard.

On 3/29/07, Thomas Malone wrote:
>
> Hello Matt.
>
> "Where as the traditional mixing methods (Soldner, Muller, and Dough
> Mixers) Do a poor job of properly mixing the clay form the start. By
> braking the clay down and getting it mixed up really well in a slurry, you
> will improve you performance dramatically."
>
> This is music to my ears! I would only negatively comment about your
> description of dry mixing being "traditional mixing methods " as wet
> mixing
> is not only traditional in many parts of the world but are also the modern
> methods. Whereas, in my experience, dry mixing is only common in heavy
> clays (bricks etc) and the USA. Wet methods, such as mixing by blunger +
> ark or by ball mills, are very widely used and long recognised as being
> much better at producing hiomogeneous mixes, wetting all the raw material
> particles and maximising the making properties. Thank you for high
> lighting
> this.
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

WJ Seidl on thu 29 mar 07


Apparently, if I want to mix half or a ton at a time, I'm going to need a
bigger garage. Maybe an old tobacco barn. And an account at Goodwill. I'm
still wearing pants I had in High School. Don't go through nearly enough of
them.
I can just imagine the "sea" of pant legs I would need swinging from the
rafters.

Ladies...don't go there!

I have looked around to see what types of used filter presses are available
on the internet at used machinery wholesalers and the like. Not cheap, are
they? And, where am I going to put the damn thing? And the pumps, and ...

I've considered Hank's suggestion about drying frames, Paul echoed it with
his suggestion for trays; but again, space is a major consideration for most
of us. Time also but space is the primary consideration.
Anyone have any ideas? I wonder if an old (maple) syrup condenser could be
made to work. Anyone have any idea of the effect on the final clay body of
boiling slurry to remove water? Waste kiln heat could be used.
Hmmmmmm.....

Wayne

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Paul Herman
Sent: Thursday, March 29, 2007 11:02 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: ancient potters, aging clay

Hi Wayne,

I think you could use a Soldner mixer for blunging slip, but if you
want to dry it in the tub by evaporation it will tie up the mixer for
a while.

I wish filter presses were more readily available to studio potters
(read cheap).

Harry Davis' book "The Potter's Companion" has plans for a vacuum
operated filter dewaterer that you can build at home. It looks like a
lot of work to put together. Has anyone on the list ever built one of
these?

You can always dry slurry in trays or old levi pant legs, but you've
got to be there at the right time to bag up the clay. When I want to
dry a batch of slip, I use a wooden tray with a hardware cloth
bottom, lined with an old sheet. It takes from a few days to a week
to get to then right consistency, depending on the weather.

Matt and Bill, welcome to clayart. I think the discussion you guys
have started here is great. After reading your posts on thorough
wetting of clay particles, I have to agree with you. Thanks for the
discussion.

Paul Herman

Great Basin Pottery
Doyle, California US
http://greatbasinpottery.com


On Mar 29, 2007, at 4:42 AM, WJ Seidl wrote:

> Question for the group:
> I got a brief glimpse these past two NCECAs at the Soldner mixer.
> It appears to be based on a rotating concrete drum.
> Does this drum not hold water?
> Would we not be able to blunge (albeit slowly) clay materials to a
> slurry in
> it, and simply allow the moisture to evaporate, or would that take
> excessively long?
>
> Failing that...does anyone have plans for a smaller filter press?
>
> Best,
> Wayne Seidl
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bryan
> Johnson
> Sent: Wednesday, March 28, 2007 11:16 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: ancient potters, aging clay
>
> Matthew Katz wrote:
>
>> The fact
>> is that that by slaking down you clay you are putting it in a slurry
>> state,
>> and aiding in throughly mixing the clay which was not accomplished
>> in the
>> first place. Where as the traditional mixing methods (Soldner,
>> Muller,
>> and
>> Dough Mixers) Do a poor job of properly mixing the clay form the
>> start. By
>> braking the clay down and getting it mixed up really well in a
>> slurry,
>> you
>> will improve you performance dramatically.
>> -snip-
>> Matt
>>
>>
>
> Since I have a Soldner mixer and a de-airing pug mill how can I use
> these tools most effectively,
> particularly when I am not mixing reclaim as part of the mix?
>
>
>
> Bryan Johnson
>
> ______________________________________________________________________
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>

____________________________________________________________________________
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Pamela Regentin on thu 29 mar 07


William & Susan Schran User wrote:
<<>>
Last night I was doing some clean-up in the studio to get ready to paint. (Studio tour coming up!) I was moving around some old boxes of clay into a damp box. I had 300-400# of recycled clay in bags waiting for a pug mill that is the greenest, slimiest stuff you'll ever see. But I also moved a few boxes of old commercially prepared clay, never opened, that had lovely brown mold spots all over the clay. Unless they prepare the clay in sterile environments, there has to be bacteria in that clay also and if left long enough it will grow stuff. We haven't determined if "organics" or "bacteria" have anything to do with the changing workability of aged clay (I"ve been trying to keep up but I may have missed a post explaining it) but it is certainly one of the evident changes as a clay gets older. I found a box of clay labeled 2001...gotta think of something special to make with that baby!

Pam


---------------------------------
Now that's room service! Choose from over 150,000 hotels
in 45,000 destinations on Yahoo! Travel to find your fit.

Matthew Katz on thu 29 mar 07


Hi,
That's great idea. I will have to add it to my list of experiments, which
unfortunately about 100 feet long. The terrible problem about this whole
discussion, is that it is not what we are actually studying right now (That
would be packing and density), but I'm sure we will come back to it.
But if anyone out there has the time. give a shout out and we will see what
we can do about setting that experiment up.
On 3/29/07, Michael Wendt wrote:
>
> I can suggest an experiment to
> decide how much organics
> contribute to clay aging and
> plastic behavior.
> One of our commercial clay
> customers buys clay for the
> retail market and the stores
> they sell to require the addition
> of a biocide to prevent mold
> and bacterial growth.
> This biocide: Nuosept 95
> is lab tested and approved
> by the Art and Craft Materials
> Institute as a skin safe material
> that can be used in things like
> finger paint and clay.
> Why not try it in some clay
> done by various means?
> Make a control batch without.
> Make an identical batch with
> Test forming character at regular
> time intervals.
> To work, it must be added to
> the water and then mixed, so
> it could also be used to test
> recycling clay.
> To be a fair test here, all slop
> and trims would need to be
> dried first. Then split into two
> equal weight piles and the
> sane amount of water added to
> both ( with one containing Nuosept).
> The final part of the puzzle would
> be to have someone other than you
> sample the two bodies without
> prior knowledge of which is
> which. If there were a color or
> smell difference, they would both
> need to be controlled for by blind-
> fold and /or nose plugs.
> For best test reliability, several testers
> would be preferable.
> Thoughts?
> Regards,
> Michael Wendt
> Wendt Pottery
> 2729 Clearwater Ave
> Lewiston, ID 83501
> USA
> 208-746-3724
> http://www.wendtpottery.com
> wendtpot@lewiston.com
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

Marcia Selsor on thu 29 mar 07


Wayne,
I have used a Soldner mixer for 27 years.
When starting with recycled slip and adding more of the same
recipe in a dry mix, the clay seems fine to me.
Also, I think a pair of old jeans works much the same as a filter press.

Marcia Selsor
http://marciaselsor.com


On Mar 29, 2007, at 7:42 AM, WJ Seidl wrote:

> Question for the group:
> I got a brief glimpse these past two NCECAs at the Soldner mixer.
> It appears to be based on a rotating concrete drum.
> Does this drum not hold water?
> Would we not be able to blunge (albeit slowly) clay materials to a
> slurry in
> it, and simply allow the moisture to evaporate, or would that take
> excessively long?
>
> Failing that...does anyone have plans for a smaller filter press?
>
> Best,
> Wayne Seidl

Leigh Whitaker on thu 29 mar 07


In a message dated 3/29/2007 4:34:13 P.M. Eastern Daylight Time,
theclaycompany@GMAIL.COM writes:

> The final part of the puzzle would
> be to have someone other than you
> sample the two bodies without
> prior knowledge of which is
> which. If there were a color or
> smell difference, they would both
> need to be controlled for by blind-
> fold and /or nose plugs.
> For best test reliability, several testers
> would be preferable.
I don't know if you guys are serious or not, but I like thinking about stuff
like this.

Just off the top of my head:

You would want to have some set tests for the testers to try (pull handle of
x length etc... and so on). Then you could have them rate the clay, like
come up with a scale of 1-10 for various factors. If you could have some non
subjective tests as well, it would be good (i.e. wrap coil of certain diameter
around a stick of a certain diameter and check for cracking, etc...) Also
some control to make sure the bactericidal agent itself doesn't affect the
plasticity of the clay one way or the other. And you'd want to decide when the
clay will be tested, how long are you going to give the bugs to grow (treat
the controls the same way of course). Some way to double check the moisture
content of the clay (to ensure all batches were similar). And maybe some way
to check how much organic material was in each batch after it's all said and
done (in other words, is the bactericidal agent actually working in the clay,
c'ause if it's not, and bugs are growing even in it's presence your tests
are shot).

Leigh



************************************** See what's free at http://www.aol.com.

Matthew Katz on thu 29 mar 07


write it up, and lets work out the details. maybe we can get people on the
board to take part


On 3/29/07, Leigh Whitaker wrote:
>
> In a message dated 3/29/2007 4:34:13 P.M. Eastern Daylight Time,
> theclaycompany@GMAIL.COM writes:
>
> > The final part of the puzzle would
> > be to have someone other than you
> > sample the two bodies without
> > prior knowledge of which is
> > which. If there were a color or
> > smell difference, they would both
> > need to be controlled for by blind-
> > fold and /or nose plugs.
> > For best test reliability, several testers
> > would be preferable.
> I don't know if you guys are serious or not, but I like thinking
> about stuff
> like this.
>
> Just off the top of my head:
>
> You would want to have some set tests for the testers to try (pull
> handle of
> x length etc... and so on). Then you could have them rate the clay, like
> come up with a scale of 1-10 for various factors. If you could have some
> non
> subjective tests as well, it would be good (i.e. wrap coil of
> certain diameter
> around a stick of a certain diameter and check for
> cracking, etc...) Also
> some control to make sure the bactericidal agent itself doesn't affect
> the
> plasticity of the clay one way or the other. And you'd want to decide
> when the
> clay will be tested, how long are you going to give the bugs to grow
> (treat
> the controls the same way of course). Some way to double check the
> moisture
> content of the clay (to ensure all batches were similar). And maybe some
> way
> to check how much organic material was in each batch after it's all said
> and
> done (in other words, is the bactericidal agent actually working in the
> clay,
> c'ause if it's not, and bugs are growing even in it's presence your tests
> are shot).
>
> Leigh
>
>
>
> ************************************** See what's free at
> http://www.aol.com.
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>



--
Matthew Katz
Alfred, NY

Dan Semler on thu 29 mar 07


Hi Wayne,

I built a rack to process clay slurry to plastic clay using frames =20
for drying. I have six frames on the right hand side about 2 x 3 out =20
of 2 x 4s. Each lined with canvas and a canvas topcover to keep the =20
beasties out. On the left hand side there are three plaster batts 2' x =20
2' a few inches thick to dry recycle on. My process is a little =20
involved but it works.

The batts are used to dry clay to bone dry. I then break it up into =20
buckets and beat it with a drill. Then pour into a drying frame and =20
slide into the rack. Wait. Pull out when about right and wedge. Its =20
still somewhat experimental froma process point of view, but it means =20
that I can do small experimental batches, or I can recycle porcelain, =20
white stoneware and dark stoneware separately.

Its less that 6' x 4' on the ground and about 6 ' high.

I get maybe 40-50lbs of plastic clay out of a tray. Not a lot but =20
then I'm not using clay that fast.

Let me know if want to see photos.

Boiling sound expensive but if you could re-route exhaust kiln heat =20
(safely) to your drying slip that might work.

Thanx
D

Michael Wendt on thu 29 mar 07


Leigh,
we had the clay we produce tested
by an independent lab in NY that
does bacterial and mold contamination
tests and they certified that at 2.5
lbs of Nuosept 95 per 400 lbs of clay,
bacterial and mold growth were
suppressed at least one year when
the tests ceased. Concern was
shelf life and product appearance
since the general public is horrified
to find mold on a product.
The lab folks were surprised about the mold
suppression (Nuosept is not a fungicide).
This all came about because a load of
clay we made went to Germany and they have
strict rule about mold and bacteria counts
in such products sold to the public.
Familie Saubermann sagt man in Deutschland. :-)
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Leigh wrote:
> to check how much organic material was in each batch
after it's all said
> and
> done (in other words, is the bactericidal agent
actually working in the
> clay,
> c'ause if it's not, and bugs are growing even in
it's presence your tests
> are shot).
>
> Leigh
>

Hank Murrow on thu 29 mar 07


On Mar 29, 2007, at 9:31 AM, WJ Seidl wrote

>
> I've considered Hank's suggestion about drying frames, Paul echoed
> it with
> his suggestion for trays; but again, space is a major consideration
> for most
> of us. Time also but space is the primary consideration.
> Anyone have any ideas? I wonder if an old (maple) syrup condenser
> could be
> made to work. Anyone have any idea of the effect on the final clay
> body of
> boiling slurry to remove water? Waste kiln heat could be used.

We're sure that you don't want to kill all those beneficial
organics........

Waste heat gently circulating under drying frames....... now that
would work.

Cheers, Hank
www.murrow.biz/hank

Vince Pitelka on thu 29 mar 07


Matthew Katz wrote:
> You are assuming that because bacteria grows, that it must have something
> to
> do with the performance of the clay. That is sort of like assuming that
> because you saw a Polar Bear at the Bronx Zoo that Polar Bears must be
> native to New York.
> We have proven that without a doubt that Mixing is the MOST important
> factor
> in the performance of all clays. and the only way to mix with complete
> effectiveness is in the slurry.

With all due respect Matt, your post comes across as a little smug. Have
you done the research to prove that the bacteria growth that accompanies
aging does not improve plasticity? It would would be a little more graceful
to acklnowledge the experience of so many potters on this list who have been
slinging clay for twenty to fifty years, and who know from long experience
that aging clay does improve plasticity.

I appreciate all that you have to say about mixing clay as a slurry, and
your theory of green particle density. I have always taught my students
that one can achieve higher plasticity with acceptible drying and firing
shrinkage by formulating a claybody with a broad but even distribution of
particle sizes. That's pretty much accepted theory among studio potters.

Regarding aging, I've never done the experiments to prove it, but my
experience tells me that the increase in organic activity that accompanies
aging flocculates and lubricates the clay, and that the "organic slime" that
is lubricating the clay also retards water absorption during throwing. So
it seems that there are a variety of things happening as a result of organic
activity that all improve plasticity and performance in a well-aged
claybody. I wish that someone would do the definitive research on the
effects of aging, so we could finally understand the systems by which
organic activity improves plasticity. Notice I did not say "if" organic
activity improves plasticity. I know that it does.

Thanks for all your contributions to the list -
- Vince

Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/

threereeds1 on fri 30 mar 07


Wayne,

Do you want to sterilize the clay?

Tom

> I've considered Hank's suggestion about drying frames, Paul echoed it with
> his suggestion for trays; but again, space is a major consideration for
> most
> of us. Time also but space is the primary consideration.
> Anyone have any ideas? I wonder if an old (maple) syrup condenser could
> be
> made to work. Anyone have any idea of the effect on the final clay body
> of
> boiling slurry to remove water? Waste kiln heat could be used.
> Hmmmmmm.....

Russel Fouts on fri 30 mar 07


>> I've considered Hank's suggestion about drying frames, Paul
echoed it with his suggestion for trays; but again, space is a major
consideration for most of us. <<

The frames can be stacked, like bunk beds but closer. ;-)

You'll also need to put some kind of peaked 'roof' on the lower ones
so they don't collect all the water from the higher ones.

Then orient one of the ends into the oncoming wind.

Russel



Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
Tel: +32 2 223 02 75
Mobile: +32 476 55 38 75

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Lee Love on fri 30 mar 07


On 3/30/07, Dan Semler wrote:

>
> Boiling sound expensive but if you could re-route exhaust kiln heat
> (safely) to your drying slip that might work.

I have put buckets of slip on the woodstove. Not a good way to dry
slip because you get a crust on the edges.

--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/

"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau

"Let the beauty we love be what we do." - Rumi

Tracey Duivestein on sun 1 apr 07


Having just toured my garden after a 2 week absence, I found that the cover
has blown off one of my 1/2 full slip/slop buckets and this has been used a
roosting place by a chicken (or maybe 2 or 3). Loads of fresh chicken shit
right into the bucket.
Don't know if I have the courage to leave it to mature & use it in my next
batch of reclaimed clay
or just to use it to fertilise the garden . Think I will let my nose decide
:-)

Tracey Duivestein
Durban, South Africa

Eleanora Eden on mon 2 apr 07


On this subject, I read somewhere that the clay doesn't start "ageing"
until it is in plastic form, not slurry form. I'm not sure this
makes sense to me.

Eleanora
--
Bellows Falls Vermont
www.eleanoraeden.com

Kathy McDonald on mon 2 apr 07


Eleanora,

That is what I learned way back when.
Not sure how much of the water has to evaporate
but I can recall some of my instructors talking
about a certain "window" of moisture content
in clay to help it age and develop plasticity.

Wish I'd taken better notes for posterity.
Many of these people are not around any longer.

Too wet and it won't develop well, too dry and it stays
too short.

Kathy


-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of
Eleanora Eden
Sent: Monday, April 02, 2007 12:48 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: ancient potters, aging clay


On this subject, I read somewhere that the clay doesn't
start "ageing"
until it is in plastic form, not slurry form. I'm not sure
this
makes sense to me.

Eleanora
--
Bellows Falls Vermont
www.eleanoraeden.com

____________________________________________________________
__________________
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Ron Roy on tue 3 apr 07


Hi Eleanora,

That is my understanding of it - and wedging helps speed it up as does
adding aged clay.

RR

>On this subject, I read somewhere that the clay doesn't start "ageing"
>until it is in plastic form, not slurry form. I'm not sure this
>makes sense to me.
>
>Eleanora

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0

Bonnie Staffel on sun 8 apr 07


I don't know if I have any facts to pass on, but I keep my clay scraps =
in
the wet stage, and about as thick as soft ice cream or pudding. It is =
full
of mold and black streaks and I add this to the new clay when working =
the
clay softer in my pug mill. It helps the new clay to age faster, IMO. =
When
I had my big studio and had apprentices, we really produced a lot of
trimming scraps so I had a big horse watering trough in the clay mixing
room. That slop was like pudding too, and we added it to the fresh dry
batches that we mixed from dry clay in the Walker pug mill. Talk about
plasticity, rot and mold, made my clay work great right from the start. =


Bonnie Staffel

Eleanora,

That is what I learned way back when.
Not sure how much of the water has to evaporate
but I can recall some of my instructors talking
about a certain "window" of moisture content
in clay to help it age and develop plasticity.

Wish I'd taken better notes for posterity.
Many of these people are not around any longer.

Too wet and it won't develop well, too dry and it stays
too short.

Kathy

http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
DVD Throwing with Coils and Slabs
DVD Introduction to Wheel Work
Charter Member Potters Council

Lee Love on mon 9 apr 07


On 3/31/07, Russel Fouts wrote:
> >> I've considered Hank's suggestion about drying frames, Paul
> echoed it with his suggestion for trays; but again, space is a major
> consideration for most of us. <<
>
> The frames can be stacked, like bunk beds but closer. ;-)

Steve Mills showed me his system with I visited Bath. He uses long
synthetic sacks that have a collar and hang by the neck in a holder.
He covers the open end with a disk, so there is no exposed top to dry
out hard. Looked like a good system to me & doen't take much room.

--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/

"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau

"Let the beauty we love be what we do." - Rumi