Dale Mark on tue 8 dec 98
Hello Kenneth
There was an article on thixotropic clay in Ceramics Monthly back in the
1970's or 1980's.
Dale Mark
Hamilton, Ont.
Stephani Stephenson on fri 8 sep 06
I inadvertently made a few hundred pounds of a very thixotropic dark
red clay, which also has a noticeable amount of soluble materials in
it... I left the clay in slip form in the mixer and returned the next
morning to find a settled mass...
too cheap to just toss it, I decided to see what I could do with
it... expecting it to be completely problematic...
..in a playful mood I decided to se what this weird clay wanted to
do...
tried a few pinch pots first, noticed that what it wanted was to be
touched gently and sparingly!
ended up building a 5 -6 foot tall coiled piece..kind of rolled and
gently tap/shook/pulled a coil/ and began building. I found that while
jelly- like, the clay stuck together marvelously, though of course
could not support much weight without distorting.. however, while it
was fairly responsive to gentle nudges and pushes, rather than the
typical pulling and pinching.
The clay set up rapidly once it was put into place . Once I got a sense
of the timing I was able to build rather rapidly . The clay showed a
tendency to split when weight and gravity pulled at it too much, but
it was responsive to mending , if the mending was tended to in good
time and the weight/gravity problem was corrected...so. I had to stay
within certain parameters of construction...touch it as little as
possible, take advantage of its properties,, keep the piece balanced as
it was built, stay conservative with projections. keep the weigh of
the pice well distributed.....
.the resulting piece is reminiscent of lava, shells, scalloped and
coral shapes....it is rock hard in green stage, having greater green
strength than I expected.
I haven't fired this yet (it is sectioned) but have fired some other
pieces with this clay... the migration of solubles in the drying
process is quite noticeable and is giving me everything from rosy pinks
to deep browns... somewhat self glazing at about cone 02...
it is very very rustic and not something I will make again but it has
been fascinating to work with...
I have been thinking about what this type of clay would be useful
for...
I imagine that many native clays exhibit certain similar properties and
so working with such a clay may be par for the course for those
working with native clays...also I couldn't help but wonder if this
more highly thixotropic clay might have been useful in brick or
architectural processes since traditional methods call for a wet ,
loose, grogged clay ... you can't possible load up the big molds with a
stiff clay... load up the big molds...
and you want a clay which sets up hard in the mold.... I have been
thinking about these old clay bodies and methods a lot.. and how they
differ
from the ones we buy today... and this thixotropic clay got me to
thinking about it again...
later I realized .doh! slipcasting is a technique which utilizes the
properties of thixotropic clays...
but I can't help wonder about other applications...
Stephani Stephenson
steph@revivaltileworks.com
http://www.revivaltileworks.com
Ivor and Olive Lewis on mon 2 oct 06
Set up a trial yesterday.
Step 1. Mix up a one percent (1.00%) solution of Dispex in water.
Step 2. Prepare a powdered sample of clay body. Sift through 60# sieve.
Step 3. Weigh out 15 grams of solution into a small flat based sealable =
container.
Step 4. Weigh out 85 grams of sifted clay powder.
Step 5. Sift powder onto the surface of the water to leave a level =
surface.
Step 6. Seal container and place in a cool place. Leave untouched over =
night.
The fluid completely saturated the clay powder and though friable at =
first it mixed to give a solid stiff plastic paste. Continued working =
caused the mass to soften and it became very pliable. I find this a =
wonderful and amazing observation. When sifting the clay into the =
deflocculating fluid it is impossible to believe so little fluid can =
saturate so much clay
I believe to get the results illustrated by Glen Nelson the proportion =
of deflocculating fluid should be increased towards 20% by weight and =
the mass of clay decreased proportionately to 80% to get that "ropy look =
fluid"=20
I hope this gives some guidance to people interested in this topic.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
=20
Ivor and Olive Lewis on fri 6 oct 06
Dear Michael Wendt,
Exactly What?
Sounds to me as though you had created a Rheopectic fluid.
When I was teaching year 12 Geology some twenty five years ago my =
students carried out a simple experiment. They took fragments of our =
local felspar, from the Port Lincoln Pegmatite Dan ground it with water =
in a pestle and mortar. This was to simulate the weathering process. The =
result was a white slurry some of which would pass through filter paper.
I may have misinterpreted what you said but it sounded as though you =
were telling us clay minerals had the same qualities as quartz sand. I =
find this difficult to believe.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Bill Merrill on sat 10 apr 10
Many years ago there was a good article on thixotropic clay. This
article was in Ceramics Monthly perhaps 30 years ago. I don't know if
CM has access to that old of an article or not. There were formulas and
pictures of the authors handles etc he made for his forms. They were
fluid and had a elegance to the curves and shapes. Rather exotic. I
will look to see if I can find that article and pass it on to those
interested. =3D20
=3D20
Bill Merrill
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