Dave Finkelnburg on sun 9 apr 00
Hi all!
I have two glazes which use a lot of clay. As you would expect, the
drying shrinkage is great, and they tend to crack, and the glaze can fall
off the ware in flakes. How would you suggest I improve the application
qualities of these glazes?
I have considered using CMC gum and also considered substituting some
calcined clay for part of the clay. I appreciate any advice/suggestions.
Thanks!
Dave Finkelnburg slightly sunburned from a real day of spring here in
Idaho
dfinkeln@cbyerhighway.net
Chris Schafale on tue 11 apr 00
Hi Dave,
I'd recommend the calcined clay -- keep about 10-15% raw clay
and replace the rest with calcined (1 gram raw clay = approx. .86
gram calcined). This has helped tremendously in reducing the
shrinkage/cracking/crawling problem for me. CMC, on the other
hand, didn't. Your mileage may vary.
Chris
> ----------------------------Original message----------------------------
> Hi all!
> I have two glazes which use a lot of clay. As you would expect, the
> drying shrinkage is great, and they tend to crack, and the glaze can fall
> off the ware in flakes. How would you suggest I improve the application
> qualities of these glazes?
> I have considered using CMC gum and also considered substituting some
> calcined clay for part of the clay. I appreciate any advice/suggestions.
> Thanks!
> Dave Finkelnburg slightly sunburned from a real day of spring here in
> Idaho
> dfinkeln@cbyerhighway.net
>
Light One Candle Pottery
Fuquay-Varina, North Carolina, USA
(south of Raleigh)
candle@intrex.net
http://www.lightonecandle.com
Paul Taylor on tue 11 apr 00
Dear david
If you defloculate the glaze you will use less water for the thickness
of the glaze and the shrinkage to dry will be less.
Mind the glaze will settle out and you will have to stir it often. You
can control the ph some what to stop it settling too much.
You will have to experiment to get a feel for the right amounts of
sodium silicate or take notes ,but that would be cheating.
Regards paul T
----------
>From: Dave Finkelnburg
>To: CLAYART@LSV.UKY.EDU
>Subject: High-clay glaze help needed
>Date: Mon, Apr 10, 2000, 2:01 am
>
>----------------------------Original message----------------------------
>Hi all!
> I have two glazes which use a lot of clay. As you would expect, the
>drying shrinkage is great, and they tend to crack, and the glaze can fall
>off the ware in flakes. How would you suggest I improve the application
>qualities of these glazes?
> I have considered using CMC gum and also considered substituting some
>calcined clay for part of the clay. I appreciate any advice/suggestions.
>Thanks!
> Dave Finkelnburg slightly sunburned from a real day of spring here in
>Idaho
> dfinkeln@cbyerhighway.net
Richard Gilbert on wed 12 apr 00
Hi Dave,
You might try roasting the clay at just a little above red heat. Then
pulverize and screen it. A mixture of raw clay and roasted clay will
control the shrinkage and preserve the chemical qualities of the
original clay.
Richard Gilbert
Cherryville, North Carolina
Ron Roy on sat 15 apr 00
Hi Dave,
Just how much clay and what kind are the questions - sometimes all that is
needed is a change if clays - to ones which have a higher MOR - stronger
dry strength.
Finer particle clays will work some times. Much depends on you water.
Calcining is one answer but not always the right one.
Certainly don't start firing them until they are dry and dry em slow.
RR
>----------------------------Original message----------------------------
>Hi all!
> I have two glazes which use a lot of clay. As you would expect, the
>drying shrinkage is great, and they tend to crack, and the glaze can fall
>off the ware in flakes. How would you suggest I improve the application
>qualities of these glazes?
> I have considered using CMC gum and also considered substituting some
>calcined clay for part of the clay. I appreciate any advice/suggestions.
>Thanks!
> Dave Finkelnburg slightly sunburned from a real day of spring here in
>Idaho
> dfinkeln@cbyerhighway.net
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Dave Finkelnburg on tue 18 apr 00
Ron,
This is really interesting! What is MOR? How does one find out what it
is for a particular clay, or possibly just for types of clay in general?
The water here is hard, not as bad as some, but generally high in
calcium, etc. How would that affect which clay to use in a recipe?
Right now I'm selecting clays mainly on iron content and size. Low clay
recipes where iron isn't an issue tend to get ball clays to aid suspension.
EPK is the lowest iron clay I have, and I use it where I want a low-iron
glaze. For high-iron glazes I have been using Redart, but not so much that
it's been a problem in application. Anyway, these are the clays.
Dave Finkelnburg
-----Original Message-----
From: Ron Roy
To: CLAYART@LSV.UKY.EDU
Date: Saturday, April 15, 2000 8:35 PM
Subject: Re: High-clay glaze help needed
----------------------------Original message----------------------------
Hi Dave,
Just how much clay and what kind are the questions - sometimes all that is
needed is a change if clays - to ones which have a higher MOR - stronger
dry strength.
Finer particle clays will work some times. Much depends on you water.
Calcining is one answer but not always the right one.
Certainly don't start firing them until they are dry and dry em slow.
RR
>----------------------------Original message----------------------------
>Hi all!
> I have two glazes which use a lot of clay. As you would expect, the
>drying shrinkage is great, and they tend to crack, and the glaze can fall
>off the ware in flakes. How would you suggest I improve the application
>qualities of these glazes?
> I have considered using CMC gum and also considered substituting some
>calcined clay for part of the clay. I appreciate any advice/suggestions.
>Thanks!
> Dave Finkelnburg slightly sunburned from a real day of spring here in
>Idaho
> dfinkeln@cbyerhighway.net
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Anji Henderson on mon 8 may 00
I got the basic set for Christmas. Really pretty. : )
I found that YES they are easy to hold and manauver..
Although either I am retarded (No Coments please) or
they arn't great for smaller pieces... They do attract
comments, and questions... And the case makes a
wonderful presentation when demonstrating..
ALTHOUGH!!! Dry the saw _really_ good before putting
the wooden case on it.....
Anji
--- Ron Roy wrote:
> ----------------------------Original
> message----------------------------
> Hi Dave - sorry this got by me - I don't know which
> way is up these days
> I'm so busy.
>
> Clay companies publish modulus of rupture numbers
> for all their clays -
> you did not include a list but here are a few.
>
> These are for 50% clay and 50% silica.
>
> C&C - 715
> New Foundry Hill cream - 700
> Tenn #1 - SGP - 410
> M7D - 1750
> Kent Stn - 610
> KTS-2 - 650
> OM#4 - 850
> EPK - 300 - see how low this is - glaze powders
> easily if no Bentonite present.
> Bell Dark - 690 - this is the one I use most.
> Pioneer - 300-400
> Tile 6 - unreliable info
>
> The quick fix is to add some (2%) bentonite - or
> reformulate using at least
> some of a clay with finer particle size.
>
> RR
> >----------------------------Original
> message----------------------------
> >Ron,
> > This is really interesting! What is MOR? How
> does one find out what it
> >is for a particular clay, or possibly just for
> types of clay in general?
> > The water here is hard, not as bad as some, but
> generally high in
> >calcium, etc. How would that affect which clay to
> use in a recipe?
> > Right now I'm selecting clays mainly on iron
> content and size. Low clay
> >recipes where iron isn't an issue tend to get ball
> clays to aid suspension.
> >EPK is the lowest iron clay I have, and I use it
> where I want a low-iron
> >glaze. For high-iron glazes I have been using
> Redart, but not so much that
> >it's been a problem in application. Anyway, these
> are the clays.
> > Dave Finkelnburg
> >-----Original Message-----
> >From: Ron Roy
> >To: CLAYART@LSV.UKY.EDU
> >Date: Saturday, April 15, 2000 8:35 PM
> >Subject: Re: High-clay glaze help needed
> >
> >
> >----------------------------Original
> message----------------------------
> >Hi Dave,
> >
> >Just how much clay and what kind are the questions
> - sometimes all that is
> >needed is a change if clays - to ones which have a
> higher MOR - stronger
> >dry strength.
> >
> >Finer particle clays will work some times. Much
> depends on you water.
> >Calcining is one answer but not always the right
> one.
> >
> >Certainly don't start firing them until they are
> dry and dry em slow.
> >
> >RR
> >
> >>----------------------------Original
> message----------------------------
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough
> Ontario, Canada
> M1G 3N8
> Evenings 416-439-2621
> Fax 416-438-7849
__________________________________________________
Do You Yahoo!?
Send instant messages & get email alerts with Yahoo! Messenger.
http://im.yahoo.com/
Ron Roy on mon 8 may 00
Hi Dave - sorry this got by me - I don't know which way is up these days
I'm so busy.
Clay companies publish modulus of rupture numbers for all their clays -
you did not include a list but here are a few.
These are for 50% clay and 50% silica.
C&C - 715
New Foundry Hill cream - 700
Tenn #1 - SGP - 410
M7D - 1750
Kent Stn - 610
KTS-2 - 650
OM#4 - 850
EPK - 300 - see how low this is - glaze powders easily if no Bentonite present.
Bell Dark - 690 - this is the one I use most.
Pioneer - 300-400
Tile 6 - unreliable info
The quick fix is to add some (2%) bentonite - or reformulate using at least
some of a clay with finer particle size.
RR
>----------------------------Original message----------------------------
>Ron,
> This is really interesting! What is MOR? How does one find out what it
>is for a particular clay, or possibly just for types of clay in general?
> The water here is hard, not as bad as some, but generally high in
>calcium, etc. How would that affect which clay to use in a recipe?
> Right now I'm selecting clays mainly on iron content and size. Low clay
>recipes where iron isn't an issue tend to get ball clays to aid suspension.
>EPK is the lowest iron clay I have, and I use it where I want a low-iron
>glaze. For high-iron glazes I have been using Redart, but not so much that
>it's been a problem in application. Anyway, these are the clays.
> Dave Finkelnburg
>-----Original Message-----
>From: Ron Roy
>To: CLAYART@LSV.UKY.EDU
>Date: Saturday, April 15, 2000 8:35 PM
>Subject: Re: High-clay glaze help needed
>
>
>----------------------------Original message----------------------------
>Hi Dave,
>
>Just how much clay and what kind are the questions - sometimes all that is
>needed is a change if clays - to ones which have a higher MOR - stronger
>dry strength.
>
>Finer particle clays will work some times. Much depends on you water.
>Calcining is one answer but not always the right one.
>
>Certainly don't start firing them until they are dry and dry em slow.
>
>RR
>
>>----------------------------Original message----------------------------
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Anji Henderson on mon 8 may 00
I got the basic set for Christmas. Really pretty. : )
I found that YES they are easy to hold and manauver..
Although either I am retarded (No Coments please) or
they arn't great for smaller pieces... They do attract
comments, and questions... And the case makes a
wonderful presentation when demonstrating..
ALTHOUGH!!! Dry the saw _really_ good before putting
the wooden case on it.....
Anji
--- Ron Roy wrote:
> ----------------------------Original
> message----------------------------
> Hi Dave - sorry this got by me - I don't know which
> way is up these days
> I'm so busy.
>
> Clay companies publish modulus of rupture numbers
> for all their clays -
> you did not include a list but here are a few.
>
> These are for 50% clay and 50% silica.
>
> C&C - 715
> New Foundry Hill cream - 700
> Tenn #1 - SGP - 410
> M7D - 1750
> Kent Stn - 610
> KTS-2 - 650
> OM#4 - 850
> EPK - 300 - see how low this is - glaze powders
> easily if no Bentonite present.
> Bell Dark - 690 - this is the one I use most.
> Pioneer - 300-400
> Tile 6 - unreliable info
>
> The quick fix is to add some (2%) bentonite - or
> reformulate using at least
> some of a clay with finer particle size.
>
> RR
> >----------------------------Original
> message----------------------------
> >Ron,
> > This is really interesting! What is MOR? How
> does one find out what it
> >is for a particular clay, or possibly just for
> types of clay in general?
> > The water here is hard, not as bad as some, but
> generally high in
> >calcium, etc. How would that affect which clay to
> use in a recipe?
> > Right now I'm selecting clays mainly on iron
> content and size. Low clay
> >recipes where iron isn't an issue tend to get ball
> clays to aid suspension.
> >EPK is the lowest iron clay I have, and I use it
> where I want a low-iron
> >glaze. For high-iron glazes I have been using
> Redart, but not so much that
> >it's been a problem in application. Anyway, these
> are the clays.
> > Dave Finkelnburg
> >-----Original Message-----
> >From: Ron Roy
> >To: CLAYART@LSV.UKY.EDU
> >Date: Saturday, April 15, 2000 8:35 PM
> >Subject: Re: High-clay glaze help needed
> >
> >
> >----------------------------Original
> message----------------------------
> >Hi Dave,
> >
> >Just how much clay and what kind are the questions
> - sometimes all that is
> >needed is a change if clays - to ones which have a
> higher MOR - stronger
> >dry strength.
> >
> >Finer particle clays will work some times. Much
> depends on you water.
> >Calcining is one answer but not always the right
> one.
> >
> >Certainly don't start firing them until they are
> dry and dry em slow.
> >
> >RR
> >
> >>----------------------------Original
> message----------------------------
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough
> Ontario, Canada
> M1G 3N8
> Evenings 416-439-2621
> Fax 416-438-7849
__________________________________________________
Do You Yahoo!?
Send instant messages & get email alerts with Yahoo! Messenger.
http://im.yahoo.com/
| |
|
