ivor and olive lewis on sat 16 jun 12

Colleagues who doubt my opinion relating to the uselessness of Halloysite a=
s
a substitute of Kaolinite as a plasticiser when constructing a workable cla=
y
body might like to consult M. Cardew, "Pioneer Pottery" p 81, Para 2.
In Tasmania there are deposits of Kaolin at Tonganah, South Mt.Cameron and
Surges Bay.
Regards,
Ivor Lewis,
REDHILL,
South Australia

Joel Browne on sun 17 jun 12

About Halloysite as
a substitute of Kaolinite as a plasticiser when constructing a workable c=
=3D
lay
body might like to consult M. Cardew, "Pioneer Pottery" p 81, Para 2.>

Just because Michael Cardew experienced difficulties does not make it
impossible, or indeed the clay useless. There are many who have long, and=
=3D

continue to, work sucessfully with the clay.

Here's an interesting article:
http://www.minerals.co.nz/html/main_topics/resources_for_schools/industri=
=3D
al_minerals/indmin_cs_halloysite.html

Joel Browne on tue 19 jun 12

Hello David,

Thank you for the thoughts and guidance. I admit to having been surprised=
=3D
to
read that the material I use, as do others, is useless! So, maybe the nex=
=3D
t
time I see containers with tonnes of the material going for export I will=
=3D

flag it all down by shouting, in the fashion of a hell-fire preacher,
"Repent! Have you not read the book, it states 'Thy shalt not use this cl=
=3D
ay.'"


Cheers, Joel.

Joel Browne on tue 19 jun 12

=3D
ng
Halloysite with water does not create a plastic clay body.> I do not
understand your comment: surely water mixed with any kaolin does not crea=
=3D
te
a clay body, and that is why other minerals such as quartz and feldspar a=
=3D
re
mixed with clay.=3D20=3D20

=3D
for
the source of plastic mechanisms cannot be ignored.> The use of the clay =
=3D
by
many can not be ignored.

Yes.

Celadon.> Well, its very low iron and titanium make it good for porcelain=
=3D

and bone china, and for me also white stoneware.

I followed the link you gave, but found another part of the site more
informative:
http://www.imerys-ceramics.com/TextsMarket.asp?I1_ID=3D3D2&I2_ID=3D3D3&am=
=3D
p;I3_ID=3D3D39&I4_ID=3D3D52

Des & Jan Howard on tue 19 jun 12

Ivor
As I remember Southern Ice & possibly Cool Ice use
halloysite as the main clay material. The workability
of SI is not at all shabby, compared with kaolin based
porcelain bodies I have made.

Accepted wisdom of what is necessary for a plastic clay
body can fall down in light of practical experience.
Our standard, quite plastic, stoneware body has 60%
very non-plastic volcanic ash which is mostly dickite,
(same formula as kaolinite, different crystal
structure), 10% cheese-like hydrothermally altered
rhyolite, (call it Lue bai dun zi) & 30% white plastic
refractory secondary kaolin.
Des

On 18/06/2012 3:36 PM, ivor and olive lewis wrote:
> Processing details at that specific source lead to the
> thought that mixing
> Halloysite with water does not create a plastic clay
> body.

--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850

02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624

Paul Herman on tue 19 jun 12

Hello All,

There is a halloysite deposit near where I live that I have been
interested in. It's currently mined by a cement company and used as a
source of alumina for the cement clinker.

This deposit is a primary clay, residing in the same place it was
formed, from hydrothermally altered tuff. It's very white and has a
high pyrometric cone equivalent, of about 35. It fires to brown
colors, so has some iron in it. If you just slake it in water, it
turns into small curved chips, and doesn't have much of any
plasticity. But it is certainly plastic and workable when milled
briefly in the ball mill. You can throw it, but the high shrinkage
(around 30%) is what stopped me from using it.

If anyone knows how other halloysite users have dealt with the
shrinkage issues, I'd be glad to hear from them. Didn't I read
somewhere that Helmer kaolin from Idaho is partly halloysite?

Best wishes,

Paul Herman

Great Basin Pottery
Doyle, California US
www.greatbasinpottery.com/