Ivor and Olive Lewis on mon 7 nov 05
Dear friends,
Reading about the Modus Operandi of this equipment, which I have seen =
illustrations, raises questions.
I appreciate that it must be most rapid way of getting a workable clay, =
But is it efficient? So many discussions in the past have centred on the =
need for a newly mixed batch of clay to "age" so that it reaches its =
optimum plastic strength.
Does rapid mixing followed by extrusion of the pugged clay allowing =
sufficient time for water to penetrate into the ingredients? Should =
newly prepared clay be set aside for a week, several weeks, or even =
several months.
Or are there special qualities we should seek in our raw materials that =
will allow immediate use, straight out of the chamber of Peter Pugger?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Michael Wendt on mon 7 nov 05
Ivor,
I don't own a Peter Pugger. Many years ago, before Peter Pugger came on the
market, I built a vacuum operation dough-style mixer which looks like a "U"
shaped trough with tight clearance mixing arms inside. They force the clay
into the side wall and shear it intensely.
When I mix a fresh batch of clay from dry powder, all the ingredients plus
the water are placed into the machine, the lid is replaced and a hard vacuum
is pulled before we begin agitation. After 20 minutes of mixing under a
vacuum, the clay is indistinguishable from clay that has been aged for
months.
I think that the vacuum first assists in allowing moisture to penetrate the
dry powder after the air is first extracted. I bet the Peter Pugger works in
the same fashion although the mix arms on their machine are more paddle
shaped rather than high shear.
Ideas?
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Ivor wrote:
Dear friends,
Reading about the Modus Operandi of this equipment, which I have seen
illustrations, raises questions.
I appreciate that it must be most rapid way of getting a workable clay, But
is it efficient? So many discussions in the past have centred on the need
for a newly mixed batch of clay to "age" so that it reaches its optimum
plastic strength.
Does rapid mixing followed by extrusion of the pugged clay allowing
sufficient time for water to penetrate into the ingredients? Should newly
prepared clay be set aside for a week, several weeks, or even several
months.
Or are there special qualities we should seek in our raw materials that will
allow immediate use, straight out of the chamber of Peter Pugger?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Vince Pitelka on mon 7 nov 05
Ivor Lewis asked:
"Does rapid mixing followed by extrusion of the pugged clay allowing
sufficient time for water to penetrate into the ingredients? Should newly
prepared clay be set aside for a week, several weeks, or even several
months."
Ivor -
I think the secret is to mix and pug the clay fairly wet, and then let it
sit for at least a week or so. I have used freshly-mixed/pugged clay plenty
of times, and it is never preferable. You are right that the great
challenge is to get the particles wet. You know what is going on, but many
people think that if they throw all the materials in the Soldner mixer or
the Peter Pugger, mix well, and then pug the clay, they will have wonderful
plastic clay ready to throw great pots, but it takes time for all those
microscopic particles to get wet through and through. And of course with
the passage of time you get organic activity, and those little things
growing in the clay release acidic byproducts which flocculate the clay and
make it ever more plastic. One of the potter's great challenges is to come
up with a clay system that allows all clay to age before it is ever used.
Certainly mixing the clay a little on the wet side is a step in the right
direction, since it wets the particles more quickly and thoroughly, and it
also accelerates organic activity.
Best wishes -
- 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/
skiasonaranthropos@FSMAIL.NET on tue 8 nov 05
Hello Ivor,
With reference to the Peter Pugger you asked =93Does rapid mixing followed
by extrusion of the pugged clay allowing sufficient time for water to
penetrate into the ingredients?=94 I wonder if this highlights an advantage
of the European preparation routes? The English method is wet ball milling
of non-plastics and the separate blunging of clays before mixing as slip
whilst the Continental approach is to wet ball mill all components
together. Both of these mean that raw material particles will be fully
wetted. Additional are the clear health and saftey benefits
Regards,
Antony
Ivor and Olive Lewis on wed 9 nov 05
Dear Antony,
Thanks for your contribution to this thread.
Ball milling will reduce mesh size of the non plastic ingredients and =
lead to a finer raw texture. I also recall many clay companies pan =
milled their raw clay stock . If this is done there is the possibility =
of reducing the thickness of the clay flakes by encouraging cleavage. =
Though this might not change the effective mesh size it would increase =
the specific surface area of the clay and enhance plasticity.
Best regards,
Ivor
skiasonaranthropos@FSMAIL.NET on thu 10 nov 05
Hello Ivor,
Thank for the email. My post to ClayArt was to highlight some differences
in technologies. Dry ball milling of non-plastics, and other dry
processing of clays, is more common in the US than Europe. The English
system of wet milling, separate blunging of clays followed by wet mixing
does maximise the wetting of raw material particles. It seems some studio
potters assume that ceramic raw materials are just dry powders rather than
processed rocks and that there may used via other production routes
Pan milling certainly had wide spread use though in my experience its long
been superseded by other, more efficient techniques. Although inducing
cleavage in a kaolinite crystal is not too easy mechanical processing of
china clays is used to delaminate stacks of particles and this causes
significant changes to making properties
Regards,
Antony
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