Craig Martell on wed 25 aug 99
Hi:
The best clay you will ever use is probably the clay you mix and prepare
yourself. Nobody cares about your clay as much as you will. It's not that
a supplier is indifferent, they are in business to make money and while
customer service is important, they have books to balance among myriads of
other concerns.
Another thing to think about is the way clay is mixed and prepared
commercially. I weigh out each ingredient when I mix my porcelain body, I
run the mixer for about 15 minutes and batch the dry ingredients very well
before I add water and finish. It then goes through the pug mill without
running the vacuum pump so it will age well. Suppliers mix by bag weight
and try to get as close as they can to the formula.. The clay is then run
through a mixer-pug unit, bagged and boxed for shipping. No matter how
well a clay is formulated, it will only be as good as the crew doing the
mixing. These guys aren't paid a high wage usually and may or may not be
concerned about how well the clay turns out. This last thing varies a lot
but is something to think about.
regards, Craig Martell in Oregon
Tamara Reid-McConkey on sat 28 aug 99
Yes, Craig, business being what it is, you have a point. However, consider
that if clay companies (or any other type of company for that matter)
consider the matter of "balancing the books" more important than the actual
product or service they provide, it won't be long before there are no books
to balance.
Tamara
Craig Martell on sun 29 aug 99
Tamara wrote:
>----------------------------Original message----------------------------
>Yes, Craig, business being what it is, you have a point. However, consider
>that if clay companies (or any other type of company for that matter)
>consider the matter of "balancing the books" more important than the actual
>product or service they provide, it won't be long before there are no books
>to balance.
>
Hi:
Yes, this is very true and I think that this may be happening to a company
near me.
I was really talking about the way large suppliers have to mix the clay to
keep production at a reasonable level so they make some dough. They can't
weigh out the materials one at a time like some of us do and sometimes
their mixes will vary and problems with the clay result. If they are
really pressed, they don't have time to average the material bag weights
and just hope they are getting close to 50 or 100 lbs per bag. My
porcelain doesn't mix well "by the bag". When I can't mix enough, I have
someone do a ton for me. I've had problems with glaze fit because the
spar/silica ratio is off. Also had warping and deairing problems because
of too much vee gum. I've never gotten a batch that has bloated, shivered,
slumped, or anything drastic like that. Just annoying little differences
from the stuff that I mix myself.
later, Craig Martell in Oregon
Stephen Grimmer on mon 30 aug 99
Craig,
You mention some problems with V Gum in your porcelain--can you
elaborate? I'm in a studio with clay mixing facilities for the first time in
3 years, and am having a devil of a time getting the air out of my
porcelain. The stuff is sort of mealy, and won't stand much bending. I've
been mixing a body with 2% V Gum T, as I have in the past, but I don't
remember such problems.
later,
steve
----------
>From: Craig Martell
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: bloating, clay, stuff
>Date: Sun, Aug 29, 1999, 12:47 PM
>
>----------------------------Original message----------------------------
>Tamara wrote:
>>----------------------------Original message----------------------------
>>Yes, Craig, business being what it is, you have a point. However, consider
>>that if clay companies (or any other type of company for that matter)
>>consider the matter of "balancing the books" more important than the actual
>>product or service they provide, it won't be long before there are no books
>>to balance.
>>
>
>Hi:
>
>Yes, this is very true and I think that this may be happening to a company
>near me.
>
>I was really talking about the way large suppliers have to mix the clay to
>keep production at a reasonable level so they make some dough. They can't
>weigh out the materials one at a time like some of us do and sometimes
>their mixes will vary and problems with the clay result. If they are
>really pressed, they don't have time to average the material bag weights
>and just hope they are getting close to 50 or 100 lbs per bag. My
>porcelain doesn't mix well "by the bag". When I can't mix enough, I have
>someone do a ton for me. I've had problems with glaze fit because the
>spar/silica ratio is off. Also had warping and deairing problems because
>of too much vee gum. I've never gotten a batch that has bloated, shivered,
>slumped, or anything drastic like that. Just annoying little differences
>from the stuff that I mix myself.
>
>later, Craig Martell in Oregon
Craig Martell on tue 31 aug 99
Steve wrote:
>----------------------------Original message----------------------------
>Craig,
> You mention some problems with V Gum in your porcelain--can you
>elaborate?
OK, I'll try.
Vee Gum is a smectite or montmorillonite as is bentonite. Very fine
grained and plastic with a clay lattice similar to kaolin but
different. This difference makes it difficult for montmorillonites to pass
water through capillary action. If you have too much vee gum or bentonite,
or macaloid in a body you may see an increased tendency to warpage from
uneven drying and higher shrinkage rates. The body may become difficult to
deair for the same reasons. Porcelains by nature are fine grained, tight
clays and if you have too much vee gum or other fine grained plasticizers
it becomes almost impossible to get good deairing. The mixing is important
too. If these plasticizers aren't dry batched well or blunged and added
wet you can get a lot of tiny air pockets in the clay that are a real bitch
kitty to remove. REAL tough. I dry batch for 10-15 minutes and it works fine.
I use a 6 tile and Kaopaque 20 porcelain mix with about 1.5% vee gum and
this works very well. I screwed up once and mixed 2.5% vee gum and it was
really bothersome. Bad deairing, sticky clay, bone dry rims with cheese
hard bases. Lower working strength. The problems I'm having now manifest
when I have a supplier mix the clay for me. They don't get it right on,
just close. Sometimes the clay is just fine. Other times it's OK, but it
could be better. Know what I mean? I think you do! :>)
Try dropping your vee gum % and see if it helps. I'd wager that it does.
later, Craig Martell in Oregon
Stephen Grimmer on wed 1 sep 99
Craig,
Thanks for the info. The porkloin I'm mixing is as follows:
30 Flint
20 G200
15 EPK
25 Tile 6
10 OM4
2 Veegum
32 H20
Veegum in blunged in H2O and the rest of the ingredients are added in the
order listed. Is Kaopaque 20 strictly necessary with T6?
I'll try dropping the Veegum down a bit. Tom Buck suggests 1% & you use
1.5%; I'll bet there's a happy medium in there somewhere.
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Craig Martell
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: bloating, clay, stuff
>Date: Tue, Aug 31, 1999, 12:04 PM
>
>----------------------------Original message----------------------------
>Steve wrote:
>>----------------------------Original message----------------------------
>>Craig,
>> You mention some problems with V Gum in your porcelain--can you
>>elaborate?
>
>
>OK, I'll try.
>
>Vee Gum is a smectite or montmorillonite as is bentonite. Very fine
>grained and plastic with a clay lattice similar to kaolin but
>different. This difference makes it difficult for montmorillonites to pass
>water through capillary action. If you have too much vee gum or bentonite,
>or macaloid in a body you may see an increased tendency to warpage from
>uneven drying and higher shrinkage rates. The body may become difficult to
>deair for the same reasons. Porcelains by nature are fine grained, tight
>clays and if you have too much vee gum or other fine grained plasticizers
>it becomes almost impossible to get good deairing. The mixing is important
>too. If these plasticizers aren't dry batched well or blunged and added
>wet you can get a lot of tiny air pockets in the clay that are a real bitch
>kitty to remove. REAL tough. I dry batch for 10-15 minutes and it works fine.
>
>I use a 6 tile and Kaopaque 20 porcelain mix with about 1.5% vee gum and
>this works very well. I screwed up once and mixed 2.5% vee gum and it was
>really bothersome. Bad deairing, sticky clay, bone dry rims with cheese
>hard bases. Lower working strength. The problems I'm having now manifest
>when I have a supplier mix the clay for me. They don't get it right on,
>just close. Sometimes the clay is just fine. Other times it's OK, but it
>could be better. Know what I mean? I think you do! :>)
>
>Try dropping your vee gum % and see if it helps. I'd wager that it does.
>
>later, Craig Martell in Oregon
Stephen Grimmer on thu 2 sep 99
Oops! I listed the clays out of order. Should be: Flint, Fpar, Ball Clay,
T6, EPK
steve
>30 Flint
>20 G200
>15 EPK
>25 Tile 6
>10 OM4
>2 Veegum
>32 H20
>
>Veegum in blunged in H2O and the rest of the ingredients are added in the
>order listed. Is Kaopaque 20 strictly necessary with T6?
>I'll try dropping the Veegum down a bit. Tom Buck suggests 1% & you use
>1.5%; I'll bet there's a happy medium in there somewhere.
>
>
>Steve Grimmer
>Bowling Green State University
>Bowling Green, OH
>
>----------
>>From: Craig Martell
>>To: CLAYART@LSV.UKY.EDU
>>Subject: Re: bloating, clay, stuff
>>Date: Tue, Aug 31, 1999, 12:04 PM
>>
>
>>----------------------------Original message----------------------------
>>Steve wrote:
>>>----------------------------Original message----------------------------
>>>Craig,
>>> You mention some problems with V Gum in your porcelain--can you
>>>elaborate?
>>
>>
>>OK, I'll try.
>>
>>Vee Gum is a smectite or montmorillonite as is bentonite. Very fine
>>grained and plastic with a clay lattice similar to kaolin but
>>different. This difference makes it difficult for montmorillonites to pass
>>water through capillary action. If you have too much vee gum or bentonite,
>>or macaloid in a body you may see an increased tendency to warpage from
>>uneven drying and higher shrinkage rates. The body may become difficult to
>>deair for the same reasons. Porcelains by nature are fine grained, tight
>>clays and if you have too much vee gum or other fine grained plasticizers
>>it becomes almost impossible to get good deairing. The mixing is important
>>too. If these plasticizers aren't dry batched well or blunged and added
>>wet you can get a lot of tiny air pockets in the clay that are a real bitch
>>kitty to remove. REAL tough. I dry batch for 10-15 minutes and it works fine
>>
>>I use a 6 tile and Kaopaque 20 porcelain mix with about 1.5% vee gum and
>>this works very well. I screwed up once and mixed 2.5% vee gum and it was
>>really bothersome. Bad deairing, sticky clay, bone dry rims with cheese
>>hard bases. Lower working strength. The problems I'm having now manifest
>>when I have a supplier mix the clay for me. They don't get it right on,
>>just close. Sometimes the clay is just fine. Other times it's OK, but it
>>could be better. Know what I mean? I think you do! :>)
>>
>>Try dropping your vee gum % and see if it helps. I'd wager that it does.
>>
>>later, Craig Martell in Oregon
Lori Pierce on fri 3 sep 99
Hi Steve, my understanding is that Tile 6 kaolin is the most plastic we mine
here in the US of A , and Kaopaque has no plasticity to speak of, but is
used for its different particle size to give tooth. Lori in New Port Richey
Fl.
-----Original Message-----
From: Stephen Grimmer
To: CLAYART@LSV.UKY.EDU
Date: Wednesday, September 01, 1999 2:23 PM
Subject: Re: bloating, clay, stuff
>----------------------------Original message----------------------------
>Craig,
> Thanks for the info. The porkloin I'm mixing is as follows:
>30 Flint
>20 G200
>15 EPK
>25 Tile 6
>10 OM4
>2 Veegum
>32 H20
>
>Veegum in blunged in H2O and the rest of the ingredients are added in the
>order listed. Is Kaopaque 20 strictly necessary with T6?
>I'll try dropping the Veegum down a bit. Tom Buck suggests 1% & you use
>1.5%; I'll bet there's a happy medium in there somewhere.
>
>
>Steve Grimmer
>Bowling Green State University
>Bowling Green, OH
>
>----------
>>From: Craig Martell
>>To: CLAYART@LSV.UKY.EDU
>>Subject: Re: bloating, clay, stuff
>>Date: Tue, Aug 31, 1999, 12:04 PM
>>
>
>>----------------------------Original message----------------------------
>>Steve wrote:
>>>----------------------------Original message----------------------------
>>>Craig,
>>> You mention some problems with V Gum in your porcelain--can you
>>>elaborate?
>>
>>
>>OK, I'll try.
>>
>>Vee Gum is a smectite or montmorillonite as is bentonite. Very fine
>>grained and plastic with a clay lattice similar to kaolin but
>>different. This difference makes it difficult for montmorillonites to
pass
>>water through capillary action. If you have too much vee gum or
bentonite,
>>or macaloid in a body you may see an increased tendency to warpage from
>>uneven drying and higher shrinkage rates. The body may become difficult
to
>>deair for the same reasons. Porcelains by nature are fine grained, tight
>>clays and if you have too much vee gum or other fine grained plasticizers
>>it becomes almost impossible to get good deairing. The mixing is
important
>>too. If these plasticizers aren't dry batched well or blunged and added
>>wet you can get a lot of tiny air pockets in the clay that are a real
bitch
>>kitty to remove. REAL tough. I dry batch for 10-15 minutes and it works
fine.
>>
>>I use a 6 tile and Kaopaque 20 porcelain mix with about 1.5% vee gum and
>>this works very well. I screwed up once and mixed 2.5% vee gum and it was
>>really bothersome. Bad deairing, sticky clay, bone dry rims with cheese
>>hard bases. Lower working strength. The problems I'm having now manifest
>>when I have a supplier mix the clay for me. They don't get it right on,
>>just close. Sometimes the clay is just fine. Other times it's OK, but it
>>could be better. Know what I mean? I think you do! :>)
>>
>>Try dropping your vee gum % and see if it helps. I'd wager that it does.
>>
>>later, Craig Martell in Oregon
>
Craig Martell on fri 3 sep 99
Steve says:
> Is Kaopaque 20 strictly necessary with T6?
Hello Steve:
The body I use was developed by Tom Turner and John Callahan. They Suggest
that you use half as much kaopaque 20 as 6 tile. Here's the receipe.
Om4 4.5%
6 Tile 29.0
Kaopaque 20 14.5
Custer 23.5
Silica 27.0
Vee Gum T 1.5
regards, Craig Martell in Oregon
Ron Roy on tue 7 sep 99
Just a note on Tile 6 - it is doctored after it comes out of the mine so I
am told - EPK is more plastic and whiter.
We test both raw materals at Tuckers as they come in so I have the numbers
and bars to prove it.
>----------------------------Original message----------------------------
>Hi Steve, my understanding is that Tile 6 kaolin is the most plastic we mine
>here in the US of A , and Kaopaque has no plasticity to speak of, but is
>used for its different particle size to give tooth. Lori in New Port Richey
>Fl.
>-----Original Message-----
>From: Stephen Grimmer
>To: CLAYART@LSV.UKY.EDU
>Date: Wednesday, September 01, 1999 2:23 PM
>Subject: Re: bloating, clay, stuff
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Stephen Grimmer on wed 8 sep 99
Hey, Ron:
Interesting to hear that about EPK. I'm testing kaolins both straight
and as sole clay components in porcelains (50 kaolin, 25 G200, 25 flint, no
plasticizer). I'll post results as they come in, so we can compare. I've
always thought T6 was exceptionally plastic, but a high shrinker and loaded
with titania. Half the iron of Grolleg. EPK is less workable and more
'sticky' due to high fines content. Haven't looked at analysis sheets or
particle size distributions recently enough to back up my statements. I
always like to be set straight by good data, tho.
From what I gather on the Dry Branch web site, the supply of white,
white Georgia kaolin (like T6 and Sapphire) is running a bit thin, and thus
the existance of the water washed and delaminated products such as Kaopaque,
Velvacast, etc. to cut the plasticity and brighten the main kaolin.
Can you add anything here?
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Ron Roy
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: bloating, clay, stuff
>Date: Tue, Sep 7, 1999, 12:43 PM
>
>----------------------------Original message----------------------------
>Just a note on Tile 6 - it is doctored after it comes out of the mine so I
>am told - EPK is more plastic and whiter.
>
>We test both raw materals at Tuckers as they come in so I have the numbers
>and bars to prove it.
>
>>----------------------------Original message----------------------------
>>Hi Steve, my understanding is that Tile 6 kaolin is the most plastic we mine
>>here in the US of A , and Kaopaque has no plasticity to speak of, but is
>>used for its different particle size to give tooth. Lori in New Port Richey
>>Fl.
>>-----Original Message-----
>>From: Stephen Grimmer
>>To: CLAYART@LSV.UKY.EDU
>>Date: Wednesday, September 01, 1999 2:23 PM
>>Subject: Re: bloating, clay, stuff
>
>Ron Roy
>93 Pegasus Trail
>Scarborough
>Ontario, Canada
>M1G 3N8
>Evenings 416-439-2621
>Fax 416-438-7849
Stephen Grimmer on fri 10 sep 99
Lori,
Cedar heights mines a stoneware called Roseville that I hear is pretty
nice. You could start with that.
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Lori Pierce
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: bloating, clay, stuff
>Date: Thu, Sep 9, 1999, 12:07 PM
>
>----------------------------Original message----------------------------
>Hi Ron, do you mean that the Tile 6 is doctored after it is mined to make it
>as plastic as it is? But, as mined, it is less plastic than EPK? My computer
>has been down for a few days and I've missed some of this. By the way, my
>supplier tells me there is no mine analysis of Lizella clay...she was quite
>funny..."You know,Lori, its just a couple of good old boys that go out with
>shovels and dig...well maybe they have a little backhoe!!" I have found I
>can get Foundry Hill Creme Stoneware clay and Kentucky Stoneware thru my
>supplier (from Standard) but she had no data and told me the last person to
>order Foundry Creme was in 1994!! Could either of them, or a combination of
>the two, replace Goldart in a body? I have no address for them...maybe in
>the Thomas Register. I've also heard there is stoneware clay up in the
>panhandle of Florida, near where the architectural ceramicist King has his
>studio, but haven't looked into it yet. Again thanks, Lori in New Port
>Richey, Fl.
>-----Original Message-----
>From: Stephen Grimmer
>To: CLAYART@LSV.UKY.EDU
>Date: Wednesday, September 08, 1999 1:07 PM
>Subject: Re: bloating, clay, stuff
>
>
>>----------------------------Original message----------------------------
>>Hey, Ron:
>> Interesting to hear that about EPK. I'm testing kaolins both straight
>>and as sole clay components in porcelains (50 kaolin, 25 G200, 25 flint, no
>>plasticizer). I'll post results as they come in, so we can compare. I've
>>always thought T6 was exceptionally plastic, but a high shrinker and loaded
>>with titania. Half the iron of Grolleg. EPK is less workable and more
>>'sticky' due to high fines content. Haven't looked at analysis sheets or
>>particle size distributions recently enough to back up my statements. I
>>always like to be set straight by good data, tho.
>> From what I gather on the Dry Branch web site, the supply of white,
>>white Georgia kaolin (like T6 and Sapphire) is running a bit thin, and thus
>>the existance of the water washed and delaminated products such as
>Kaopaque,
>>Velvacast, etc. to cut the plasticity and brighten the main kaolin.
>> Can you add anything here?
>>
>>Steve Grimmer
>>Bowling Green State University
>>Bowling Green, OH
>>
>>----------
>>>From: Ron Roy
>>>To: CLAYART@LSV.UKY.EDU
>>>Subject: Re: bloating, clay, stuff
>>>Date: Tue, Sep 7, 1999, 12:43 PM
>>>
>>
>>>----------------------------Original message----------------------------
>>>Just a note on Tile 6 - it is doctored after it comes out of the mine so I
>>>am told - EPK is more plastic and whiter.
>>>
>>>We test both raw materals at Tuckers as they come in so I have the numbers
>>>and bars to prove it.
>>>
>>>>----------------------------Original message----------------------------
>>>>Hi Steve, my understanding is that Tile 6 kaolin is the most plastic we
>mine
>>>>here in the US of A , and Kaopaque has no plasticity to speak of, but is
>>>>used for its different particle size to give tooth. Lori in New Port
>Richey
>>>>Fl.
>>>>-----Original Message-----
>>>>From: Stephen Grimmer
>>>>To: CLAYART@LSV.UKY.EDU
>>>>Date: Wednesday, September 01, 1999 2:23 PM
>>>>Subject: Re: bloating, clay, stuff
>>>
>>>Ron Roy
>>>93 Pegasus Trail
>>>Scarborough
>>>Ontario, Canada
>>>M1G 3N8
>>>Evenings 416-439-2621
>>>Fax 416-438-7849
>>
Ron Roy on sat 11 sep 99
Hi Steve,
I'll just quote from some of the test data I have here at home - keep in
mind - when I look at the test bars - fired at cone 10 reduction of
porcelains - it's always the EPK that is the whitest.
I'll just average the numbers in my head so they will not be dead accurate
- but will be in the ball park.
----------------------------------------------------------------------------
----------------------------
Tile 6 1944 to 98
Dry shrinkage 5 to 7% except for 4 pallets in 1996 when the absorbency was
up and the dry shrinkage was 3.5 to 4.0%
Fired shrinkage (cone 10R) Highest 18.2 - lowest 15.0 the average about
17.0 and the 4 bad pallets were 13.0 to 14.0
Absorbency at cone 10R 5.2 lowest and highest 9.1,- average about 7.5 and
the bad pallets averaged over 9%
----------------------------------------------------------------------------
---------------------------
EPK I have a lot more data starting before 1990 I'll just give a typical
page from Jan 96 to Dec. 96.
Dry shrinkage lowest 6.0 - highest is 8.5 with the average about 7% - so
more plastic than Tile 6.
Fired shrinkage fired to C10R - lowest 15.0 - highest 19.0 average is about
17.5.
Absorbency at cone 10R - lowest 9.5 - highest is 13.5 with an average about
11.5.
This means you can still use the white none plastic kaolins to get whiter
but because the EPK is more plastic you can use more of them - does that
seem reasonable to you?
RR
>----------------------------Original message----------------------------
>Hey, Ron:
> Interesting to hear that about EPK. I'm testing kaolins both straight
>and as sole clay components in porcelains (50 kaolin, 25 G200, 25 flint, no
>plasticizer). I'll post results as they come in, so we can compare. I've
>always thought T6 was exceptionally plastic, but a high shrinker and loaded
>with titania. Half the iron of Grolleg. EPK is less workable and more
>'sticky' due to high fines content. Haven't looked at analysis sheets or
>particle size distributions recently enough to back up my statements. I
>always like to be set straight by good data, tho.
> From what I gather on the Dry Branch web site, the supply of white,
>white Georgia kaolin (like T6 and Sapphire) is running a bit thin, and thus
>the existance of the water washed and delaminated products such as Kaopaque,
>Velvacast, etc. to cut the plasticity and brighten the main kaolin.
> Can you add anything here?
>
>Steve Grimmer
>Bowling Green State University
>Bowling Green, OH
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Stephen Grimmer on sun 12 sep 99
Ron,
I can confirm the whiteness of EPK over T6 in a porcelain body. Got some
test mice out of the kiln last night, and the EPK was clearly whiter than
both the straight T6 body and the T6/Kaopaque 20 mix. No shrinkage,
absorbtion, or workability data yet, though. I'll post results soon.
Have you ever mixed a body with EPK as the sole kaolin component? How is
it for workability? I have a few pounds waiting for a little aging and some
free time for me to work with it. I will also mix up a couple of batches
using EPK/Kaopaque as the kaolin part, and post those results.
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Ron Roy
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: bloating, clay, stuff
>Date: Sat, Sep 11, 1999, 5:19 PM
>
>----------------------------Original message----------------------------
>Hi Steve,
>
>I'll just quote from some of the test data I have here at home - keep in
>mind - when I look at the test bars - fired at cone 10 reduction of
>porcelains - it's always the EPK that is the whitest.
>
>I'll just average the numbers in my head so they will not be dead accurate
>- but will be in the ball park.
>
>----------------------------------------------------------------------------
>----------------------------
>
>Tile 6 1944 to 98
>
>Dry shrinkage 5 to 7% except for 4 pallets in 1996 when the absorbency was
>up and the dry shrinkage was 3.5 to 4.0%
>
>Fired shrinkage (cone 10R) Highest 18.2 - lowest 15.0 the average about
>17.0 and the 4 bad pallets were 13.0 to 14.0
>
>Absorbency at cone 10R 5.2 lowest and highest 9.1,- average about 7.5 and
>the bad pallets averaged over 9%
>
>----------------------------------------------------------------------------
>---------------------------
>
>EPK I have a lot more data starting before 1990 I'll just give a typical
>page from Jan 96 to Dec. 96.
>
>Dry shrinkage lowest 6.0 - highest is 8.5 with the average about 7% - so
>more plastic than Tile 6.
>
>Fired shrinkage fired to C10R - lowest 15.0 - highest 19.0 average is about
>17.5.
>
>Absorbency at cone 10R - lowest 9.5 - highest is 13.5 with an average about
>11.5.
>
>This means you can still use the white none plastic kaolins to get whiter
>but because the EPK is more plastic you can use more of them - does that
>seem reasonable to you?
>
>RR
>>----------------------------Original message----------------------------
>>Hey, Ron:
>> Interesting to hear that about EPK. I'm testing kaolins both straight
>>and as sole clay components in porcelains (50 kaolin, 25 G200, 25 flint, no
>>plasticizer). I'll post results as they come in, so we can compare. I've
>>always thought T6 was exceptionally plastic, but a high shrinker and loaded
>>with titania. Half the iron of Grolleg. EPK is less workable and more
>>'sticky' due to high fines content. Haven't looked at analysis sheets or
>>particle size distributions recently enough to back up my statements. I
>>always like to be set straight by good data, tho.
>> From what I gather on the Dry Branch web site, the supply of white,
>>white Georgia kaolin (like T6 and Sapphire) is running a bit thin, and thus
>>the existance of the water washed and delaminated products such as Kaopaque,
>>Velvacast, etc. to cut the plasticity and brighten the main kaolin.
>> Can you add anything here?
>>
>>Steve Grimmer
>>Bowling Green State University
>>Bowling Green, OH
>
>Ron Roy
>93 Pegasus Trail
>Scarborough
>Ontario, Canada
>M1G 3N8
>Evenings 416-439-2621
>Fax 416-438-7849
Ron Roy on tue 14 sep 99
Hi Steve,
The great majority of the porcelains I look after are only EPK and ball
clay at cones 6,8 and 10.
I'm not saying they are white - but they have better working qualities than
the whiter porcelains and glazes look great on them - which is one if the
reasons for working with clays that have less than ideal working
charatcheristics.
RR
>----------------------------Original message----------------------------
>Ron,
> I can confirm the whiteness of EPK over T6 in a porcelain body. Got some
>test mice out of the kiln last night, and the EPK was clearly whiter than
>both the straight T6 body and the T6/Kaopaque 20 mix. No shrinkage,
>absorbtion, or workability data yet, though. I'll post results soon.
> Have you ever mixed a body with EPK as the sole kaolin component? How is
>it for workability? I have a few pounds waiting for a little aging and some
>free time for me to work with it. I will also mix up a couple of batches
>using EPK/Kaopaque as the kaolin part, and post those results.
>
>Steve Grimmer
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Lori Pierce on wed 15 sep 99
Lori here again, Ron. Got my pugmill all apart to switch from the darker
clays to your lighter ^6 bodies from Axner...tho the storm may hold up
delivery of the samples. If they work out well I may go with one of them
instead of making my own! Brent told me he could mix the body as soft as I
wanted as long as I was willing to wait for the body run I wanted...and I
can. Today I've lugged and hauled everything I can inside, and hope my two
hugh oaks out back are firmly anchored. Looks like we will be on the very
fringe of Floyd here,tho.Lots of rain and tornadoes expected.
Question...what would I add to a well fitting slip to make it crawl a bit?
Looking for ways to add interest to certain oxidation pots. A clay with a
higher shrinkage than the pot I suppose.I found a reference in Susan
Peterson's book, the Craft and Art of Clay; and I quote, "Liquid clays used
on top of glazes before firing produce shrinkage patterns called crawling";
however the pot I've seen appeared to have the glaze over the slip.
Its really great having your help, Ron. Thanks. Lori in New Port Richey
Fl...trying to think 'clay', not "hurricane".
-----Original Message-----
From: Ron Roy
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, September 14, 1999 4:45 PM
Subject: Re: bloating, clay, stuff
----------------------------Original message----------------------------
Hi Steve,
The great majority of the porcelains I look after are only EPK and ball
clay at cones 6,8 and 10.
I'm not saying they are white - but they have better working qualities than
the whiter porcelains and glazes look great on them - which is one if the
reasons for working with clays that have less than ideal working
charatcheristics.
RR
>----------------------------Original message----------------------------
>Ron,
> I can confirm the whiteness of EPK over T6 in a porcelain body. Got
some
>test mice out of the kiln last night, and the EPK was clearly whiter than
>both the straight T6 body and the T6/Kaopaque 20 mix. No shrinkage,
>absorbtion, or workability data yet, though. I'll post results soon.
> Have you ever mixed a body with EPK as the sole kaolin component? How
is
>it for workability? I have a few pounds waiting for a little aging and
some
>free time for me to work with it. I will also mix up a couple of batches
>using EPK/Kaopaque as the kaolin part, and post those results.
>
>Steve Grimmer
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Ron Roy on thu 16 sep 99
Hi Lori,
The short answer is - I don't really know because I have never done that -
but the first thing I would try would be to flocculate the slip -
flocculated slip will get thick and you will have to add water - clay with
more water shrinks more so - eventually it will have to start cracking -
maybe too much - in that case don't add so much vinegar or Epson salts.
Vinegar will flocculate clay fast - try a small amount of slip - say half a
cup - and add a few drops of vinegar or more till it thickens - thin it out
- add more vinegar etc. eventually it won't thicken anymore - then try it -
keep track of how much vinegar you add - then you will be able to mix up
more as you need it. Don't try to store clay with vinegar in it - unless
you have a strong stomach.
Epson salts will do it too - dissolve 5 spoonfuls in a cup of very hot
water - put it in a squirt bottle and add drops - like above.
Thats all I can think of at the moment.
RR
>----------------------------Original message----------------------------
>Question...what would I add to a well fitting slip to make it crawl a bit?
>Looking for ways to add interest to certain oxidation pots. A clay with a
>higher shrinkage than the pot I suppose.I found a reference in Susan
>Peterson's book, the Craft and Art of Clay; and I quote, "Liquid clays used
>on top of glazes before firing produce shrinkage patterns called crawling";
>however the pot I've seen appeared to have the glaze over the slip.
>Its really great having your help, Ron. Thanks. Lori in New Port Richey
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Earl Brunner on fri 17 sep 99
This got me thinking. I recently combined two buckets of glaze in the ceramic
lab. The resultant glaze was a nice oxidation green at cone 6. Both formulas
were relatively harmless in terms of toxic materials. So I wasn't too worried
about toxic problems. I did encounter a problem with the "new" glaze. After it
had set around for a couple of days it got extremely thick, (flocculated)
right? The only real culprit I could see was that one of the glazes had
Gerstley Borate in it, but there are no doubt other factors. Watering it down
of course cased application problems. My question is: When a glaze does this,
is there something you can do to deflocculate the glaze? I looked in Hamer and
didn't really get or understand how what he was could be applied to this
problem.
Ron Roy wrote:
> ----------------------------Original message----------------------------
> Hi Lori,
>
> The short answer is - I don't really know because I have never done that -
> but the first thing I would try would be to flocculate the slip -
> flocculated slip will get thick and you will have to add water - clay with
> more water shrinks more so - eventually it will have to start cracking -
> maybe too much - in that case don't add so much vinegar or Epson salts.
>
> Vinegar will flocculate clay fast - try a small amount of slip - say half a
> cup - and add a few drops of vinegar or more till it thickens - thin it out
> - add more vinegar etc. eventually it won't thicken anymore - then try it -
> keep track of how much vinegar you add - then you will be able to mix up
> more as you need it. Don't try to store clay with vinegar in it - unless
> you have a strong stomach.
>
> Epson salts will do it too - dissolve 5 spoonfuls in a cup of very hot
> water - put it in a squirt bottle and add drops - like above.
>
> Thats all I can think of at the moment.
>
> RR
>
> >----------------------------Original message----------------------------
> >Question...what would I add to a well fitting slip to make it crawl a bit?
> >Looking for ways to add interest to certain oxidation pots. A clay with a
> >higher shrinkage than the pot I suppose.I found a reference in Susan
> >Peterson's book, the Craft and Art of Clay; and I quote, "Liquid clays used
> >on top of glazes before firing produce shrinkage patterns called crawling";
> >however the pot I've seen appeared to have the glaze over the slip.
> >Its really great having your help, Ron. Thanks. Lori in New Port Richey
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough
> Ontario, Canada
> M1G 3N8
> Evenings 416-439-2621
> Fax 416-438-7849
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Ron Roy on sun 19 sep 99
Two approaches to this - washing the glaze - add lots of water - stir well
and leave to settle - take off all the free water the next day and dump it
- do all over again - say 3 times - this gets rid of some of the solubles.
It that is not enough - take off as much water as possible and add some
dissolved Epsom salts - can't tell you how much - it depends on the amount
of glaze and how deflocced it is. Add to thick glaze - spoonful at a time -
when the glaze starts to thin out it is getting defloccked. I would wait at
least a minute between spoonfuls - the reaction is delayed - just keep
stirring for that minute.
If the application problems are gone stop. If not get the glaze thick again
and do it again.
Send me the recipe for the new glaze and I will reformulate so a new batch
will not have the problem.
RR
>----------------------------Original message----------------------------
>This got me thinking. I recently combined two buckets of glaze in the ceramic
>lab. The resultant glaze was a nice oxidation green at cone 6. Both formulas
>were relatively harmless in terms of toxic materials. So I wasn't too worried
>about toxic problems. I did encounter a problem with the "new" glaze.
>After it
>had set around for a couple of days it got extremely thick, (flocculated)
>right? The only real culprit I could see was that one of the glazes had
>Gerstley Borate in it, but there are no doubt other factors. Watering it down
>of course cased application problems. My question is: When a glaze does this,
>is there something you can do to deflocculate the glaze? I looked in Hamer and
>didn't really get or understand how what he was could be applied to this
>problem.
>
>Ron Roy wrote:
>
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Louis H.. Katz on sun 19 sep 99
Gertsley is a tough one because it really seems to have quite a bit of soluble
material in it. You might try really watering it down, 1 gallon of glaze five
gallons of water, letting it settle, and then removing the water. Good luck.
Louis
Earl Brunner wrote:
> ----------------------------Original message----------------------------
> This got me thinking. I recently combined two buckets of glaze in the ceramic
> lab. The resultant glaze was a nice oxidation green at cone 6. Both formulas
> were relatively harmless in terms of toxic materials. So I wasn't too worried
> about toxic problems. I did encounter a problem with the "new" glaze. After
> had set around for a couple of days it got extremely thick, (flocculated)
> right? The only real culprit I could see was that one of the glazes had
> Gerstley Borate in it, but there are no doubt other factors. Watering it down
> of course cased application problems. My question is: When a glaze does this
> is there something you can do to deflocculate the glaze? I looked in Hamer an
> didn't really get or understand how what he was could be applied to this
> problem.
>
> Ron Roy wrote:
>
> > ----------------------------Original message----------------------------
> > Hi Lori,
> >
> > The short answer is - I don't really know because I have never done that -
> > but the first thing I would try would be to flocculate the slip -
> > flocculated slip will get thick and you will have to add water - clay with
> > more water shrinks more so - eventually it will have to start cracking -
> > maybe too much - in that case don't add so much vinegar or Epson salts.
> >
> > Vinegar will flocculate clay fast - try a small amount of slip - say half a
> > cup - and add a few drops of vinegar or more till it thickens - thin it out
> > - add more vinegar etc. eventually it won't thicken anymore - then try it -
> > keep track of how much vinegar you add - then you will be able to mix up
> > more as you need it. Don't try to store clay with vinegar in it - unless
> > you have a strong stomach.
> >
> > Epson salts will do it too - dissolve 5 spoonfuls in a cup of very hot
> > water - put it in a squirt bottle and add drops - like above.
> >
> > Thats all I can think of at the moment.
> >
> > RR
> >
> > >----------------------------Original message----------------------------
> > >Question...what would I add to a well fitting slip to make it crawl a bit?
> > >Looking for ways to add interest to certain oxidation pots. A clay with a
> > >higher shrinkage than the pot I suppose.I found a reference in Susan
> > >Peterson's book, the Craft and Art of Clay; and I quote, "Liquid clays used
> > >on top of glazes before firing produce shrinkage patterns called crawling";
> > >however the pot I've seen appeared to have the glaze over the slip.
> > >Its really great having your help, Ron. Thanks. Lori in New Port Richey
> >
> > Ron Roy
> > 93 Pegasus Trail
> > Scarborough
> > Ontario, Canada
> > M1G 3N8
> > Evenings 416-439-2621
> > Fax 416-438-7849
>
> --
> Earl Brunner
> http://coyote.accessnv.com/bruec
> mailto:bruec@anv.net
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