Re: Please tell me more about Petunse in the USA

[Hank Murrow]

On Jun 17, 2008, at 7:07 AM, Antoinette Badenhorst wrote:

Thanks for the information Hank. Maybe there is hopes that somewhere in future America will be able to rely on these deposits for their porcelain. Do you get similar translucency as with the southern ice pots you showed me before?

Dear Antoinette;

My Calf Ridge porcelainstone when hydrothermally altered also was contaminated by iron and titania, rendering tthe body not translucent..... if drop dead gorgeous. The Fairbanks AK porcelainstone prospected and mined by David Stannard is indeed translucent at cone 8 reduction. I will post a pic of this Alaskan body fired in oxidation and reduction. The glaze is the body with 15% limestone added. Rings like a bell for a long time when struck, and you can count your fingers through the body when held to the light. I will post the photo at the flickr site  http://www.flickr.com/photos/claycraft/   so you can see.

Cheers, Hank

[Gail Fullerton]

Hank,

Where or where did David find his AK porcelain?

Gail in Fairbanks

btw I have the gas kiln running and the cone 6 reduction is looking very very good

[Hank Murrow]

Dear gail;

He called it "Silver Fox" and it was on a U of Alaska site. He has found several other sites which he now uses.

Cheers, Hank

[hambone]

It's worth looking at David Stannard's writing on the topic as well
as Tichane's and Nigel Wood's. Wood reports the UPA for the earliest
Five Dynasties Jingdezhen petuntse which was used as 100% of the clay
body. Stannard's Silver Fox actually has fewer impurities - judging by
the UPA numbers.
H A M B O N E

[hambone]

p.s. extrusive (volcanic) primary clays are covered slightly in Cardew
also.

What is also interesting here is that all kaolins in the USA are
secondary clays hence
Hanks and Stannard's use of this material represents the very unusual
use of primary local clay material (as a clay body) in the USA.

H A M B O N E

[Hank Murrow]

On Jul 1, 2008, at 4:06 PM, hambone wrote:

> p.s. extrusive (volcanic) primary clays are covered slightly in Cardew
> also.
>
> What is also interesting here is that all kaolins in the USA are
> secondary clays hence
> Hanks and Stannard's use of this material represents the very unusual
> use of primary local clay material (as a clay body) in the USA.

Dear Eric;

When I realised what Stannard was on to, I soon found that there are
deposits of rhyolite all over the West. In desert areas, there has
been little alteration due to the dry climate which prevails there.
In CA, OR, WA, and AK, there has been much hydrothermal alteration
(because of volcanic geysering), leading to the development of
sericite and micaceous minerals. These are plastic and have the right
amount of alkali for a mature body at cone 10 (around 3_4%). In the
absence of hydrothermal or heavy weathering, there would be too much
alkalii content for cone 10 fires..... at least as the main body
ingredient.

The problem as I see it is that potters brought up in the lore of
Western porcelain have been inclined to search for kaolins and
feldspars....... giving extrusive rocks little to no attention. I am
confident that we will find and develop such deposits as soon as many
potters start looking for them. the maps have been drawn..... it
remains for potters to look for the right things.

Cheers, Hank