[Clayart] Feldspar Follies

[Dean]

I had some trouble with a new batch of a glaze that is 54% Custer, it looked under fluxed. I searched ClayArt and found a discussion on the changed chemistry of Custer (7% K instead of 10%, 75% Si instead of 69%, etc).  This would explain how my glaze looked quite well so I'm doing some tests to sort it out. However, Jon Brooks at Laguna sent me the Pacer data sheets for their Custer shipments for the last 3 years and none of them show the 3% drop in Potassium that was discussed on ClayArt or any other significant change in chemistry. they all had around 10% K and 69% Si.  So what is the chemistry of Custer now really?  Where did that  altered chemistry info come from?


Jon also confirmed that G-200HP will no longer be available after December 2013.  It will be replaced by G-200SP, imported from Spain, similar chemistry as the old G-200 and probably more expensive.

In other news, do you know how Custer is mined?  This is the story I heard, though I could hardly believe it.  Maybe someone on ClayArt can confirm or correct it.  Chunks of Custer rocks are picked up off the ground by hand by industrious individuals, hauled, and sold to Pacer who grades, crushes and packages it. In this age of giant mining machines and miles deep mines this seems rather retro and inefficient, doesn't it?  And isn't it hard to procure the vast tonnages of rock that are needed to meet the demand?
Dean in hot Kauai

 
www.lightwavepottery.com
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[Michael McDowell]

Dean,

I think there is a lesson for us all in the disparity you point out.
Pacer's data sheets for Custer Feldspar do not correspond with
independent analyses done on the very same batches. I did find an
analysis on the Pacer web site over a year ago that corresponds with the
data Ron Roy presents in his November article in Ceramics Monthly. But
while I was on the site, the link to that analysis was deleted.

Ron has been very careful to avoid blaming or finger pointing while
pointing out the variance between what Pacer publishes as the current
analysis for Custer Spar and what independent analysis can verify. I
have difficulty doing the same when this topic comes up...

Michael McDowell
Whatcom County Washington
www.McDowellPottery.com

On 10/19/2013 5:00 AM, clayart...@ceramicist.org wrote:
> I had some trouble with a new batch of a glaze that is 54% Custer, it looked under fluxed. I searched ClayArt and found a discussion on the changed chemistry of Custer (7% K instead of 10%, 75% Si instead of 69%, etc).? This would explain how my glaze looked quite well so I'm doing some tests to sort it out. However, Jon Brooks at Laguna sent me the Pacer data sheets for their Custer shipments for the last 3 years and none of them show the 3% drop in Potassium that was discussed on ClayArt or any other significant change in chemistry. they all had around 10% K and 69% Si.? So what is the chemistry of Custer now really?? Where did that? altered chemistry info come from?

[Robert Harris]

Dean - I was one of those that sent my Custer (bought in 2011) for analysis.

The analysis that Custer and Pacer gives out appears to be accurate for
samples from the early 2000s. All recent samples (and I'm afraid I have no
data on when the change occurred), have shown the low KNa numbers.
Fortunately the new stuff does at least seem to be consistent.

Ron and I discussed how to present this. Pacer was not interested in
hearing about it.

Robert

--
----------------------------------------------------

[Lee]

On Sat, Oct 19, 2013 at 5:17 AM, Dean <mang...@yahoo.com> wrote:

>
> In other news, do you know how Custer is mined? This is the story I
> heard, though I could hardly believe it. Maybe someone on ClayArt can
> confirm or correct it. Chunks of Custer rocks are picked up off the ground
> by hand by industrious individuals, hauled, and sold to Pacer who grades,
> crushes and packages it.

I got rock samples from Continental Clay and crushed them in Craig Edwards'
rock crusher. I've found that this works very well to get the
Ko-shigaraki effect in my clay reformulations.

I last bought a sack of Custer Chicken Grit. I do not know if it
is publicly available or if Continental sold me their sample. The grit
is easier to crush because it is already small bits.

I just made some tea bowls putting crushed Custer in
Continental's Woodfire Porcelain, that I add some helmer to.
--
Lee 李 Love in Longfellow,Minneapolis, MN USA

"Ta tIr na n-óg ar chul an tI—tIr dlainn trina chéile"—that is, "The land
of eternal youth is behind the house, a beautiful land fluent within
itself." -- John O'Donohue

[Paul Herman]

Hi Dean,

I was another one who got my Custer Feldspar analyzed. My samples are
identified as "from the southwest" in Ron's article.

I tried to talk to the folks at Pacer Minerals and they went through
the following antics.

1. Deny everything

2. Imply that I wasn't really a potter, and that I got the (bad)
information off the internet tubes.

3. Attack the messenger

4. Poke their heads in the sand

5. Circle the wagons

6. Deny everything

So now it looks like Custer is going to be the only operating feldspar
mine in the US. I'm glad I bought a ton of the G-200 HP. It should
last me a few years....

best wishes,

Paul Herman

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

[ron...@ca.inter.net]

Hi Dean,

My article on the subject will be in the November issue of CM - they
have allowed me to publish it on my web site starting in November if
you don't subscribe.

The G200 SP (Spruce Pine) is not going to happen - instead a Spanish
potash spare will be imported and will be close to the original G200 -
it will be called G200 EU.

Pacer is sending out analysis that don't reflect their current product
- the only way you can be sure what you have is have an analysis done
- if you want the names of some labs I can send them.

IF you want me to adjust your glaze to look like it did using the
Custer you have send me the recipe.

RR

Ron Roy
ron...@ca.inter.net

[John Hesselberth]

On Oct 19, 2013, at 3:06 PM, ron...@ca.inter.net wrote:

> My article on the subject will be in the November issue of CM - they have allowed me to publish it on my web site starting in November if you don't subscribe.

Yes, Ron Roy finally has a web site. It is still "under construction" so don't be harsh with your comments. But do check out his gallery. It is a historical perspective of his work. For those who have never seen Ron's pots you will be very pleasantly surprised at how talented a potter he is. And, of course, you will recognize the cover pot for our book among many others.

Oh, the URL is www.ronroy.net

Remember it is .net, not .com --.com is some guy that writes children's books -- definitely not our Ron.

Regards,

John


Mastering Cone 6 Glazes is now available as an eBook. Check it out at:
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[Michael Wendt]

Custer Feldspar is used as filler in things like plastics where fluxing
power is not a concern so we are pretty much on our own in this one. Sadly,
the Moose Creek Feldspar project is on hold because of litigation about who
now controls the mineral leases. Until that is resolved, the 500, 000 tons
of high grade ore just sits on the ground.
For the record, the method I used to refine it, selective milling, yields
K2O values in the 10% + range consistently so if the legal issues can be
resolved, the practical aspects of producing a low cost domestic kspar
become a reality for many years to come.
Regards,
Michael Wendt
www.wendtpottery.com

[ivor and olive lewis]

Potash Feldspar SF/01
Silica SiO2 68% ( + 1% )
Alumina Al2O3 18% ( + 1% )
Sodium Oxide Na2O 2% ( + 0.5% )
Potassium Oxide K2O 11.50% ( + 0.5% )
Titanium Oxide TiO2 Nil
Calcium Oxide CaO 0.50%
Magnesium Oxide MgO Traces
Ferric Oxide Fe2O3 0.08% ( + 0.05% )
Loss On Ignition LOI 0.40%

Website: http://www.hindexports.net/

Specification

Analysis K-spar 01 K-spar 02 K-spar 03
SiO2 67.50% (± 01.00%) 69.50% (± 01.00%) 72.50% (± 02.00%)
Al2O3 17.75% (± 00.50%) 17.05% (± 00.50%) 15.50% (± 01.00%)
K2O 12.10% (± 00.60% 10.00% (± 00.50%) 08.00% (± 01.00%)
Na2O 02.50% (± 00.80%) 02.50% (± 00.80%) 02.75% (± 01.00%)
Fe2O3 00.07% (± 00.01%) 00.10 (± 00.02%) 00.20 (± 00.05%)
CaO Nil Nil Nil
MgO Nil Nil Nil
TiO2 Nil Nil Nil
LoI @ 1000oC

From http://www.guptagrinding.com/potassium- feldspar.htm

BHP Billiton have a new prospect for Potash Felspar in Canada...The
Jansen Project, located 140 kilometres east of Saskatoon, Saskatchewan, is
our most advanced project and is in feasibility study stage.

Who do we have close to this site. Try to get hold of a sample for
testing
Did not take long to find suppliers if I wanted to get 20 tonnes.
There seems to be a lot of this stuff to be had Some of the assays look
really promising.

Regards,
Ivor Lewis,
REDHILL,
South Australia.
















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