Hank Murrow on fri 30 mar 07
Matt;
Thanks, Bob james has developed wonderful metaphors for nearly
anything one might encounter in ceramics. Made him a joy to listen to
and still does. He is still kicking at 78............ and a frequent
guest at tea.
Cheers, Hank
On Mar 30, 2007, at 6:44 PM, Matthew Katz wrote:
> Hi Hank.
> I use that metaphor too. It is great, tried and true. I keep trying
> to come
> up with a new one... Its a Jello salad... no,no.. It's a lego
> castle...
> nawww. none of them stand up to the room full of balls. Although I
> always
> finish with sand, to tie the whole thing together.
> I'm glad to know that you had such a wise teacher.
>> Dear Matt;
>>
>> This sounds like what my old(he's now 78) ceramics prof used to call,
>> "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
>> from teachers like Laura Andreson and Maija Grotell, who probably
>> advocated this as well.
>>
>> the idea is that you select the widest range of particle size
>> distribution, so that a room full of basketballs still has room for
>> oranges between, and shooter marbles between the oranges, and peas
>> between those, and bbs between the peas, etc. The larger particles
>> keep the body from shrinking too much, while the ever smaller
>> particles create the plasticity. Win/win.
>>
>> Very glad to hear that you are here in this forum advocating such a
>> sensible(and I mean that in an ambiguous way) proposal.
>>
>> Cheers, Hank
>> www.murrow.biz/hank
>>
>>
>> _____________________________________________________________________
>> _________
>> 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
>
> ______________________________________________________________________
> ________
> 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
www.murrow.biz/hank
Lynne and Bruce Girrell on fri 30 mar 07
Matt,
First, let me thank you for taking the time to sign on to Clayart to address
the plasticity/workability issue.
I have been wondering about something regarding the packing density issue.
Suppose that I take some kaolin and ball mill the daylights out of it so
that I break up the platelets into a spectrum of particle sizes with many
fines. I then mix this slurry in along with my "normal" porcelain clay body,
blunge, press, and wedge to a working state.
Now, by some miracle, I find a ball clay that has a very similar particle
size distribution to the ball-milled additive above and I process in the
same way, excluding the ball milling, since I already have the fines.
Because the particle size range of my ball clay and my ball-milled kaolin is
similar and I follow in each case with the same processing methods, I would
expect my green packing density to be very similar for the two clay bodies.
Would you or would you not expect a difference in workability between the
two clays? The ball clay has a naturally higher tortuosity, surface area,
and CEC so while the particle size distribution of my two batches should be
very similar, the particles themselves are different.
Essentially, I am asking if you think that the packing density is pretty
much the big story or is there much more going on?
Bruce Girrell
_________________________________________________________________
5.5%* 30 year fixed mortgage rate. Good credit refinance. Up to 5 free
quotes - *Terms
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Matthew Katz on fri 30 mar 07
Ugh,
Well, first Hello,
Ugh, because I just wrote you a response, and my email hiccuped and it
disappeared.
So I will write more later, but I need to get diner on the table. '
But this is my short answer.. short... Ha!
Ball milling for the most part will not enhance PSD and subsequently GPD,
all it will do is make extremely short clays because of the concentration of
small particles. Small particles do not pack well, for evidence on this try
making a body of only EPK (which is very small)
What i have found that works best is to work with combinations of materials
that have natural size differences. The best example of this is a stoneware.
The recipes that I come across over and over again is blends of Gold Art
(small) OM4 (Medium) and Hawthorne (Large). these different size materials
work together to fill the interstitial spaces in the body, this makes the
clay much stronger and more rigid. Where as the generic porcelain recipe is
composed of only Grolleg. By having only one clay it creates huge amounts of
open space (relatively) in the body. This makes the clay very floppy, and
unstable on the wheel. This is why you will something see recipes that call
for adding ball clays to porcelains, because it enhances the GPD and makes
the clay more stable.
So is GPD the only thing going on? No there is a lot more, but I would say
that is is a huge player. But the fact is that these are things that artists
have always known. We are just giving it a name, and applying the same
principle to to all clay bodies.
More to come, but now onto diner.
On 3/30/07, Lynne and Bruce Girrell wrote:
>
> Matt,
>
> First, let me thank you for taking the time to sign on to Clayart to
> address
> the plasticity/workability issue.
>
> I have been wondering about something regarding the packing density issue.
>
> Suppose that I take some kaolin and ball mill the daylights out of it so
> that I break up the platelets into a spectrum of particle sizes with many
> fines. I then mix this slurry in along with my "normal" porcelain clay
> body,
> blunge, press, and wedge to a working state.
>
> Now, by some miracle, I find a ball clay that has a very similar particle
> size distribution to the ball-milled additive above and I process in the
> same way, excluding the ball milling, since I already have the fines.
> Because the particle size range of my ball clay and my ball-milled kaolin
> is
> similar and I follow in each case with the same processing methods, I
> would
> expect my green packing density to be very similar for the two clay
> bodies.
>
> Would you or would you not expect a difference in workability between the
> two clays? The ball clay has a naturally higher tortuosity, surface area,
> and CEC so while the particle size distribution of my two batches should
> be
> very similar, the particles themselves are different.
>
> Essentially, I am asking if you think that the packing density is pretty
> much the big story or is there much more going on?
>
> Bruce Girrell
>
> _________________________________________________________________
> 5.5%* 30 year fixed mortgage rate. Good credit refinance. Up to 5 free
> quotes - *Terms
>
> https://www2.nextag.com/goto.jsp?product=100000035&url=%2fst.jsp&tm=y&search=mortgage_text_links_88_h2a5d&s=4056&p=5117&disc=y&vers=910
>
>
> ______________________________________________________________________________
> 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 fri 30 mar 07
On Mar 30, 2007, at 2:55 PM, Matthew Katz wrote:
>
> What i have found that works best is to work with combinations of
> materials
> that have natural size differences. The best example of this is a
> stoneware.
> The recipes that I come across over and over again is blends of
> Gold Art
> (small) OM4 (Medium) and Hawthorne (Large). these different size
> materials
> work together to fill the interstitial spaces in the body, this
> makes the
> clay much stronger and more rigid. Where as the generic porcelain
> recipe is
> composed of only Grolleg. By having only one clay it creates huge
> amounts of
> open space (relatively) in the body. This makes the clay very
> floppy, and
> unstable on the wheel. This is why you will something see recipes
> that call
> for adding ball clays to porcelains, because it enhances the GPD
> and makes
> the clay more stable.
> So is GPD the only thing going on? No there is a lot more, but I
> would say
> that is is a huge player. But the fact is that these are things
> that artists
> have always known. We are just giving it a name, and applying the
> same
> principle to to all clay bodies.
Dear Matt;
This sounds like what my old(he's now 78) ceramics prof used to call,
"The Room Full of Basketballs Theory of Clay Mixing". Bob James came
from teachers like Laura Andreson and Maija Grotell, who probably
advocated this as well.
the idea is that you select the widest range of particle size
distribution, so that a room full of basketballs still has room for
oranges between, and shooter marbles between the oranges, and peas
between those, and bbs between the peas, etc. The larger particles
keep the body from shrinking too much, while the ever smaller
particles create the plasticity. Win/win.
Very glad to hear that you are here in this forum advocating such a
sensible(and I mean that in an ambiguous way) proposal.
Cheers, Hank
www.murrow.biz/hank
Matthew Katz on fri 30 mar 07
Hi Hank.
I use that metaphor too. It is great, tried and true. I keep trying to come
up with a new one... Its a Jello salad... no,no.. It's a lego castle...
nawww. none of them stand up to the room full of balls. Although I always
finish with sand, to tie the whole thing together.
I'm glad to know that you had such a wise teacher.
Best,
Matt
On 3/30/07, Hank Murrow wrote:
>
> On Mar 30, 2007, at 2:55 PM, Matthew Katz wrote:
> >
> > What i have found that works best is to work with combinations of
> > materials
> > that have natural size differences. The best example of this is a
> > stoneware.
> > The recipes that I come across over and over again is blends of
> > Gold Art
> > (small) OM4 (Medium) and Hawthorne (Large). these different size
> > materials
> > work together to fill the interstitial spaces in the body, this
> > makes the
> > clay much stronger and more rigid. Where as the generic porcelain
> > recipe is
> > composed of only Grolleg. By having only one clay it creates huge
> > amounts of
> > open space (relatively) in the body. This makes the clay very
> > floppy, and
> > unstable on the wheel. This is why you will something see recipes
> > that call
> > for adding ball clays to porcelains, because it enhances the GPD
> > and makes
> > the clay more stable.
> > So is GPD the only thing going on? No there is a lot more, but I
> > would say
> > that is is a huge player. But the fact is that these are things
> > that artists
> > have always known. We are just giving it a name, and applying the
> > same
> > principle to to all clay bodies.
>
> Dear Matt;
>
> This sounds like what my old(he's now 78) ceramics prof used to call,
> "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
> from teachers like Laura Andreson and Maija Grotell, who probably
> advocated this as well.
>
> the idea is that you select the widest range of particle size
> distribution, so that a room full of basketballs still has room for
> oranges between, and shooter marbles between the oranges, and peas
> between those, and bbs between the peas, etc. The larger particles
> keep the body from shrinking too much, while the ever smaller
> particles create the plasticity. Win/win.
>
> Very glad to hear that you are here in this forum advocating such a
> sensible(and I mean that in an ambiguous way) proposal.
>
> Cheers, Hank
> www.murrow.biz/hank
>
>
> ______________________________________________________________________________
> 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
Ivor and Olive Lewis on sat 31 mar 07
Dear Bruce Girrell,
You say << The ball clay has a naturally higher tortuosity,>>
Does this mean that Ball clay particles (which were as I understand =
things was originally Kaolin that has been transported) loose their =
original plane hexagonal crystalline configuration and ends up looking =
like a rolled and twisted potato chips.
If Kaolin and Ball clay have similar properties to the other =
Phyllosilicates, they are highly flexible cookies which are difficult to =
break across the grain but split well along a prominent cleavage plane, =
as does Muscovite Mica. Even Selenite, a massive crystalline form of =
Gypsum, can be cleaved into thin flexible sheets.
I would like to know about this Green Packing Density coefficient and to =
see some of the images. Is this quality calculated with water present or =
does it only apply to the dry minerals?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
WJ Seidl on sat 31 mar 07
Hank, Matt and all:
I'm still having a bit of a problem wrapping my mind around this.
If one takes a box and fills it with softballs there is room between the
softballs for movement, and when the box is shaken, the balls will move.
If one packs smaller particles (the shooter marbles and BBs you mention)
to eliminate some of the gaps between the softballs, wouldn't the
balls tend to move _less_ because everything is now packed in tighter?
We practice this when packing for shipping. We box a pot, packing it in
bubblewrap, seal the box. Then we put that box in a larger one, packing that
one also "so that the inside box with the pot _does_not_move_during
shipment" (emphasis mine).
Were this packing smaller and smaller particles into gaps (green packing
density referred to in other posts) to _aid_ plasticity, then the same would
be true of our shipping box example. By packing the box densely, we would
be _encouraging_ movement (plasticity). Instead, we are accomplishing
exactly the opposite. We pack tightly so that things do NOT move.
How is this thinking incorrect?
Best,
Wayne Seidl
Dear Matt;
This sounds like what my old(he's now 78) ceramics prof used to call,
"The Room Full of Basketballs Theory of Clay Mixing". Bob James came
from teachers like Laura Andreson and Maija Grotell, who probably
advocated this as well.
the idea is that you select the widest range of particle size
distribution, so that a room full of basketballs still has room for
oranges between, and shooter marbles between the oranges, and peas
between those, and bbs between the peas, etc. The larger particles
keep the body from shrinking too much, while the ever smaller
particles create the plasticity. Win/win.
Very glad to hear that you are here in this forum advocating such a
sensible(and I mean that in an ambiguous way) proposal.
Cheers, Hank
www.murrow.biz/hank
____________________________________________________________________________
__
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 sat 31 mar 07
Dear Wayne;
The problem of visualization here is that I proposed an example using
round particles. In fact, clay particles are plate-like in form. This
allows them to move and slide around each other with the water
holding them to their surfaces by ionic attraction. Visualize two
glass laboratory slides with a drop of water between them. they slide
but do not pull apart. It is also useful to remember that a 325 mesh
feldspar particle is the size of a small building if an average clay
particle were the size of a fingernail. Now you can see the immense
surface area clay presents to hold water. The reason Bentonite is so
plastic is that there is an extra silica lattice and twice the area
for water to cling to.
Cheers, Hank
On Mar 31, 2007, at 5:50 AM, WJ Seidl wrote:
> Hank, Matt and all:
> I'm still having a bit of a problem wrapping my mind around this.
> If one takes a box and fills it with softballs there is room
> between the
> softballs for movement, and when the box is shaken, the balls will
> move.
> If one packs smaller particles (the shooter marbles and BBs you
> mention)
> to eliminate some of the gaps between the softballs, wouldn't the
> balls tend to move _less_ because everything is now packed in tighter?
>
> We practice this when packing for shipping. We box a pot, packing
> it in
> bubblewrap, seal the box. Then we put that box in a larger one,
> packing that
> one also "so that the inside box with the pot _does_not_move_during
> shipment" (emphasis mine).
>
> Were this packing smaller and smaller particles into gaps (green
> packing
> density referred to in other posts) to _aid_ plasticity, then the
> same would
> be true of our shipping box example. By packing the box densely,
> we would
> be _encouraging_ movement (plasticity). Instead, we are accomplishing
> exactly the opposite. We pack tightly so that things do NOT move.
>
> How is this thinking incorrect?
> Best,
> Wayne Seidl
>
> Dear Matt;
>
> This sounds like what my old(he's now 78) ceramics prof used to call,
> "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
> from teachers like Laura Andreson and Maija Grotell, who probably
> advocated this as well.
>
> the idea is that you select the widest range of particle size
> distribution, so that a room full of basketballs still has room for
> oranges between, and shooter marbles between the oranges, and peas
> between those, and bbs between the peas, etc. The larger particles
> keep the body from shrinking too much, while the ever smaller
> particles create the plasticity. Win/win.
>
> Very glad to hear that you are here in this forum advocating such a
> sensible(and I mean that in an ambiguous way) proposal.
>
> Cheers, Hank
> www.murrow.biz/hank
>
> ______________________________________________________________________
> ______
> __
> 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.
Hank Murrow
www.murrow.biz/hank
Lynne and Bruce Girrell on sat 31 mar 07
>Ball milling for the most part will not enhance PSD and subsequently GPD,
>all it will do is make extremely short clays because of the concentration
>of
>small particles. Small particles do not pack well,
Yes, I understand that. I think that you may have missed my point. In my
hypothetical situation, I mixed the ball-milled kaolin back into the normal
porcelain clay body formula, blunged the mixture and pressed that.
What I was trying to set up was a situation where I was filling in the
larger gaps of the porcelain body with broken down kaolin platelets in one
case and ball clays in the other. So, to me, it would seem that if I were
able to mill kaolin to create a PSD similar to that of the ball clays, then
the GPD of my porcelain + milled kaolin should be the same as the GPD of my
porcelain + ball clay.
Don't worry about the practicality of doing so. That's not the point either.
Just assume that I can.
Now, if I can create two clays, one with the small interstitial spaces
occupied by milled kaolin and the other with the spaces occupied by ball
clay particles and both having the same PSD:
1) Would you consider the GPD to be the same? (I would say yes)
2) Would you expect the workability to be the same? (I am guessing no)
The milled kaolin would simply be a bunch of flat plates. The ball clay,
even though of the same physical size, is a much more complex shape with an
attendant increased surface area and water layer.
If GPD is the major story, then my two clays should exhibit similar
workability. If there is another significant agent at work, then the two
clays would still exhibit different workability despite having the same GPD
(and that would provide a new direction to look when trying to quantify
workability).
Thinking in terms of the concept of principle components, perhaps GPD is the
first principle component. What would be the second? And how would they
compare in magnitude?
Switching to a different subject that has been introduced. I find analogies
to be very powerful teaching tools. They provide a means by which an
unfamiliar concept can be related to something familiar. Tina Gebhart made a
beautiful anaolgy with her colored Jello, fruit in Jello, and candy covered
fruit in Jello (was there a fourth one?). That's a description that anyone
old enough to eat Jello can relate to.
Bruce Girrell
_________________________________________________________________
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Lynne and Bruce Girrell on sat 31 mar 07
Wayne Seidl wrote:
>I'm still having a bit of a problem wrapping my mind around this.
>If one takes a box and fills it with softballs there is room between the
>softballs for movement, and when the box is shaken, the balls will move.
>If one packs smaller particles (the shooter marbles and BBs you mention)
>to eliminate some of the gaps between the softballs, wouldn't the
>balls tend to move _less_ because everything is now packed in tighter?
At some point, yes. That's why increasing packing density beyond a certain
point decreases the workability, as Matt showed on his slide. Also, as Hank
has pointed out, don't forget that we're woking with a wet and electrically
unbalanced system.
Bruce Girrell
_________________________________________________________________
The average US Credit Score is 675. The cost to see yours: $0 by Experian.
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Matthew Katz on sat 31 mar 07
Sorry,
I misunderstood your hypothetical. I guess I would think of it more of,
"What if a Ball Clay and Kaolin had exactly the same structure and PSD".
Also removing any inherent Non plastics (residual quartz or sand) Because
the non plastics also play a huge role in the packing efficiency of a
system. They create the largest balls in the room (in the room full of
Balls metaphor). This is why Grogs make clays more rugged because they
provide another level of size distribution to enhance GPD. So If all those
factors were removed from the equation. Than I would say yes they would have
the same GPD. but in fact by doing that you for the most part have exactly
the same clay because kaolins and ball clays are all composed from the same
kaolinitic base, +/- Iron and titanium content. All those variables removed.
I would expect the clays to work the same.
As far as the second component of workability. I would say it is water. But
the great thing about water is that is it infinitely adjustable. But water
only effects if the material is "Hard", Low moisture content (19-20%) or
"Soft" (23-24%). These factors play almost no effect on GPD but does have a
major effect on if a person likes to work with that clay. I have friends
that only like soft clays. and my finance only likes extremely hard. but the
water content different is only about 3% from a soft clay Water is a whole
nother beast, but it is very easy to control. But GPD is independent of
moisture content, because water is only filling the last of the interstitial
spaces. the variations of +/-3-5% are not enough of a variable to effect
the GPD.
Best,
Matt
On 3/31/07, Lynne and Bruce Girrell wrote:
>
> Wayne Seidl wrote:
>
> >I'm still having a bit of a problem wrapping my mind around this.
> >If one takes a box and fills it with softballs there is room between the
> >softballs for movement, and when the box is shaken, the balls will move.
> >If one packs smaller particles (the shooter marbles and BBs you mention)
> >to eliminate some of the gaps between the softballs, wouldn't the
> >balls tend to move _less_ because everything is now packed in tighter?
>
> At some point, yes. That's why increasing packing density beyond a certain
> point decreases the workability, as Matt showed on his slide. Also, as
> Hank
> has pointed out, don't forget that we're woking with a wet and
> electrically
> unbalanced system.
>
> Bruce Girrell
>
> _________________________________________________________________
> The average US Credit Score is 675. The cost to see yours: $0 by Experian.
>
> http://www.freecreditreport.com/pm/default.aspx?sc=660600&bcd=EMAILFOOTERAVERAGE
>
>
> ______________________________________________________________________________
> 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
Chris Trabka on sat 31 mar 07
Wayne,
When you are thinking about the closed box, it has a fixed amount of space
that is rigid. Consider an open garbage sack that allows things to move
filled with various sizes of "peanuts".
Chris
Matthew Katz on sat 31 mar 07
The metaphor I like to use for the way clay particles stick together is wet
playing cards, They shift laterally, but have strength to stick together
based on their extensive surface area. Although in clays it the the
alternating charge , one side of a clay particle is negative while the other
side is positive that keeps them together
On 3/31/07, Hank Murrow wrote:
>
> Dear Wayne;
>
> The problem of visualization here is that I proposed an example using
> round particles. In fact, clay particles are plate-like in form. This
> allows them to move and slide around each other with the water
> holding them to their surfaces by ionic attraction. Visualize two
> glass laboratory slides with a drop of water between them. they slide
> but do not pull apart. It is also useful to remember that a 325 mesh
> feldspar particle is the size of a small building if an average clay
> particle were the size of a fingernail. Now you can see the immense
> surface area clay presents to hold water. The reason Bentonite is so
> plastic is that there is an extra silica lattice and twice the area
> for water to cling to.
>
> Cheers, Hank
>
>
> On Mar 31, 2007, at 5:50 AM, WJ Seidl wrote:
>
> > Hank, Matt and all:
> > I'm still having a bit of a problem wrapping my mind around this.
> > If one takes a box and fills it with softballs there is room
> > between the
> > softballs for movement, and when the box is shaken, the balls will
> > move.
> > If one packs smaller particles (the shooter marbles and BBs you
> > mention)
> > to eliminate some of the gaps between the softballs, wouldn't the
> > balls tend to move _less_ because everything is now packed in tighter?
> >
> > We practice this when packing for shipping. We box a pot, packing
> > it in
> > bubblewrap, seal the box. Then we put that box in a larger one,
> > packing that
> > one also "so that the inside box with the pot _does_not_move_during
> > shipment" (emphasis mine).
> >
> > Were this packing smaller and smaller particles into gaps (green
> > packing
> > density referred to in other posts) to _aid_ plasticity, then the
> > same would
> > be true of our shipping box example. By packing the box densely,
> > we would
> > be _encouraging_ movement (plasticity). Instead, we are accomplishing
> > exactly the opposite. We pack tightly so that things do NOT move.
> >
> > How is this thinking incorrect?
> > Best,
> > Wayne Seidl
> >
> > Dear Matt;
> >
> > This sounds like what my old(he's now 78) ceramics prof used to call,
> > "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
> > from teachers like Laura Andreson and Maija Grotell, who probably
> > advocated this as well.
> >
> > the idea is that you select the widest range of particle size
> > distribution, so that a room full of basketballs still has room for
> > oranges between, and shooter marbles between the oranges, and peas
> > between those, and bbs between the peas, etc. The larger particles
> > keep the body from shrinking too much, while the ever smaller
> > particles create the plasticity. Win/win.
> >
> > Very glad to hear that you are here in this forum advocating such a
> > sensible(and I mean that in an ambiguous way) proposal.
> >
> > Cheers, Hank
> > www.murrow.biz/hank
> >
> > ______________________________________________________________________
> > ______
> > __
> > 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.
>
> Hank Murrow
> www.murrow.biz/hank
>
>
> ______________________________________________________________________________
> 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 sat 31 mar 07
The problem is that packing peanuts are not use to pack to a maximum
density. They are actually meant to move quite a bit. so If a box is
dropped, say on a corner, the peanuts shift inside the packaging to absorb
the shock. If the Peanuts were packed to maximum density, the work inside
would break because it would be the unmovable object that would absorb the
shock.
On 3/31/07, WJ Seidl wrote:
>
> Hank, Matt and all:
> I'm still having a bit of a problem wrapping my mind around this.
> If one takes a box and fills it with softballs there is room between the
> softballs for movement, and when the box is shaken, the balls will move.
> If one packs smaller particles (the shooter marbles and BBs you mention)
> to eliminate some of the gaps between the softballs, wouldn't the
> balls tend to move _less_ because everything is now packed in tighter?
>
> We practice this when packing for shipping. We box a pot, packing it in
> bubblewrap, seal the box. Then we put that box in a larger one, packing
> that
> one also "so that the inside box with the pot _does_not_move_during
> shipment" (emphasis mine).
>
> Were this packing smaller and smaller particles into gaps (green packing
> density referred to in other posts) to _aid_ plasticity, then the same
> would
> be true of our shipping box example. By packing the box densely, we would
> be _encouraging_ movement (plasticity). Instead, we are accomplishing
> exactly the opposite. We pack tightly so that things do NOT move.
>
> How is this thinking incorrect?
> Best,
> Wayne Seidl
>
> Dear Matt;
>
> This sounds like what my old(he's now 78) ceramics prof used to call,
> "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
> from teachers like Laura Andreson and Maija Grotell, who probably
> advocated this as well.
>
> the idea is that you select the widest range of particle size
> distribution, so that a room full of basketballs still has room for
> oranges between, and shooter marbles between the oranges, and peas
> between those, and bbs between the peas, etc. The larger particles
> keep the body from shrinking too much, while the ever smaller
> particles create the plasticity. Win/win.
>
> Very glad to hear that you are here in this forum advocating such a
> sensible(and I mean that in an ambiguous way) proposal.
>
> Cheers, Hank
> www.murrow.biz/hank
>
>
> ____________________________________________________________________________
> __
> 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
Ivor and Olive Lewis on sun 1 apr 07
Dear Hank Murrow=20
I wondered about space for the water, but for differing reasons.
You suggest <water between them. they slide but do not pull apart.>>.=20
Well, having played around with microscope slides and cover slips for =
close to sixty five years I recalled that your visualisation differed =
from my experience. If you have a thin layer of water between the two =
slides there is a high degree of friction. It is very difficult to slide =
one cover slip past the other. It takes force to make the glass slide =
past glass unless there is a lot of water, enough to exude from between =
the sheets. So I checked. Just did it with a couple of brand new cover =
slips. Almost impossible to make one slide past the other.
I think that this illustrates the proposition that clay water systems =
would not have the properties they do have if water was such a good =
lubricant. The words of Lawrence and West seem wise to me.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on sun 1 apr 07
Dear Bruce Girrell,
<ball clays, then
the GPD of my porcelain + milled kaolin should be the same as the GPD of =
my
porcelain + ball clay.>>
Can you give us an expansion of the cyphers you are using for these =
peculiar clay qualities. Without knowing your code I am lost.
I did ball mill samples of Kaolin a couple of years ago. Not sure what =
happened because an optical microscope will not readily resolve the =
images. But it was an interesting experience
Thanks,
Ivor
Matthew Katz on sun 1 apr 07
Hi,
The garbage bag idea is not far off. By packing more material into the
system it does not lock it up. it just makes it so that it takes more stress
to move the system while improving the internal strength of the body
So if you had that bag not quite full of beach balls and that the bag was
laying on the ground so that all of the ball inside were in contact with the
ground. Say you change the shape of the bag so all of the balls form a
pyramid ,it will move fairly easily. But because the system is not well
packed. Then it will fall down because the balls have no internal structure
to stand up and they all fall flat again. This is what porcelain is like.
Now let's say that you fill the bag with all of those other sized balls, and
you try and form that same pyramid. Now it takes a little more force to
make the shape (not much more though), but it now holds its shape, all of
those smaller balls are helping to hold they system up and work as a whole.
This is what a well packed porcelain or stoneware is like.
Hope that helps.
Matt
On 3/31/07, Hank Murrow wrote:
>
> Dear Wayne;
>
> The problem of visualization here is that I proposed an example using
> round particles. In fact, clay particles are plate-like in form. This
> allows them to move and slide around each other with the water
> holding them to their surfaces by ionic attraction. Visualize two
> glass laboratory slides with a drop of water between them. they slide
> but do not pull apart. It is also useful to remember that a 325 mesh
> feldspar particle is the size of a small building if an average clay
> particle were the size of a fingernail. Now you can see the immense
> surface area clay presents to hold water. The reason Bentonite is so
> plastic is that there is an extra silica lattice and twice the area
> for water to cling to.
>
> Cheers, Hank
>
>
> On Mar 31, 2007, at 5:50 AM, WJ Seidl wrote:
>
> > Hank, Matt and all:
> > I'm still having a bit of a problem wrapping my mind around this.
> > If one takes a box and fills it with softballs there is room
> > between the
> > softballs for movement, and when the box is shaken, the balls will
> > move.
> > If one packs smaller particles (the shooter marbles and BBs you
> > mention)
> > to eliminate some of the gaps between the softballs, wouldn't the
> > balls tend to move _less_ because everything is now packed in tighter?
> >
> > We practice this when packing for shipping. We box a pot, packing
> > it in
> > bubblewrap, seal the box. Then we put that box in a larger one,
> > packing that
> > one also "so that the inside box with the pot _does_not_move_during
> > shipment" (emphasis mine).
> >
> > Were this packing smaller and smaller particles into gaps (green
> > packing
> > density referred to in other posts) to _aid_ plasticity, then the
> > same would
> > be true of our shipping box example. By packing the box densely,
> > we would
> > be _encouraging_ movement (plasticity). Instead, we are accomplishing
> > exactly the opposite. We pack tightly so that things do NOT move.
> >
> > How is this thinking incorrect?
> > Best,
> > Wayne Seidl
> >
> > Dear Matt;
> >
> > This sounds like what my old(he's now 78) ceramics prof used to call,
> > "The Room Full of Basketballs Theory of Clay Mixing". Bob James came
> > from teachers like Laura Andreson and Maija Grotell, who probably
> > advocated this as well.
> >
> > the idea is that you select the widest range of particle size
> > distribution, so that a room full of basketballs still has room for
> > oranges between, and shooter marbles between the oranges, and peas
> > between those, and bbs between the peas, etc. The larger particles
> > keep the body from shrinking too much, while the ever smaller
> > particles create the plasticity. Win/win.
> >
> > Very glad to hear that you are here in this forum advocating such a
> > sensible(and I mean that in an ambiguous way) proposal.
> >
> > Cheers, Hank
> > www.murrow.biz/hank
> >
> > ______________________________________________________________________
> > ______
> > __
> > 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.
>
> Hank Murrow
> www.murrow.biz/hank
>
>
> ______________________________________________________________________________
> 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
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