iandol on mon 16 apr 01
Dear Vince Pitelka,
I would be pleased if you would provide me with your references to =
experimental investigations which validate claims that the platey clay =
crystals become aligned when we are throwing clay.=20
My own experience is that the clay fabric undergoes considerable shear =
due to the retardation effect of holding clay against the rotation of =
the wheel. Repeated coning sets up a circulating extrusion pattern.
Another problem which concerns me is the way information relating to the =
behaviour of plastic clay ignores the development, structure and =
properties of flock units. When we make plastic clay we create and deal =
with a flock structure which is not a simple mixture of clay and non =
plastics lubricated by water. When flock structure is considered, the =
explanations for plasticity and the behaviour of plastic clay given in =
popular commentaries written for ceramic artists must be questioned.
Thank you for making a contribution to this debate.
Best regards,
Ivor.
will edwards on tue 17 apr 01
Grasshoppa,
Go to Pg. 300 in Hamers, 'The Potter's Dictionary' read about shale. Then=
go
and film yourself throwing and watch it in slow motion. You are in fact
compresing particles under pressure while the wheel is continully turning=
in
an opposing direction. Shear force such as in homogination and platelet
particles aligning themselves as they dry should be recognized. So both o=
f you
are right! Don't leave out ionic and colloidal effect of layering and wat=
er
evaporation. Compression + ionic particles charge =3D Good clay + colloid=
s =3D
Better clay (thus termed 'Plastic')
Take a lake bed where someone has found some real decent clay but it is
cracked up and looks like a glaze that shivered and crawled right off the=
pot.
No compression available to it but yet it is plastic when compressed and =
ready
to throw as is. Then of course those long lost veins of clay that was
originally compressed when some action of the Earth took place such as be=
tween
viens of coal. The first one lacked any particle compression and was rela=
xed
as it dried and the shale or layers went undisturbed creating breakage.
Meaning the larger platelets and heavier particles were left to fall to t=
he
bottom of the layer while the colloidal remnants remained on the very top=
=2E
Thus the layering effect!
Thus shear force and redistribution and variety of particles based on
aggregates and rotation would set the pace for the nano-meter particles a=
nd
ionic charged clays forming and bonding to create aligned particles slowl=
y as
it dries. Without compression via rotation and pressure coupled with exce=
sive
water the alignment of particles is loose and unable to pull together fir=
mly
thus allowing cracks and poor body due to over drying in one area while
another area is still weak and lacks compression due to saturation and
layering of platelets with a fluid. The Illustrated Dictionary of Practic=
le
Pottery is a good book to read as well.
Ivor said>>>>Dear Vince Pitelka,
I would be pleased if you would provide me with your references to
experimental
investigations which validate claims that the platey clay crystals become=
aligned when we are throwing clay. end<<<<
William Edwards
Alchemy 101 - I should have stayed in bed. Sandwiched and layered between=
the
heavy and the light particles called a mattress and a sheet. However the
colloids in my life floated me right off the mattress! I think I woke up =
in a
negative charged state but some hot water should realease my bonds with t=
hat
in a few minutes.
____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=3D=
1
iandol on wed 18 apr 01
Dear will edwards,
I think you are confusing several points in your post. Your information =3D
does not address the question I put to Vince which was
experimental investigations which validate claims that the platey clay =3D
crystals become aligned when we are throwing clay.>=3D20
Neither Hamer and Hamer nor Robert Fournier give anything about Flock =3D
structure. Though H & H do talk about flocculation it is only in the =3D
context of clay preparation.
So Will, can you direct me to records of experimental investigations =3D
which validate your assertion that kaolinite crystals align when you =3D
press them down with your thumb?
Thank you for contributing to this thread.
Best regards,
Ivor Lewis, Redhill, South Australia
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