=?iso-8859-1?Q?Ren=E9?= Sprattling on thu 4 feb 99

Sandy,

Don't forget that the type of clay you use can effect the outcome of the
glaze. Try test tiles of the same glaze on several different clays and see
what happens. Sure wish I were a biochemist!

Rene in Sunny Cold CA

---------------Original message---------------------------

>One problem that appeared in 2 glazes that were close in color was for
>a Lavender, and Purple Icing glazes, both of which came out blue. I'm
>not sure how to remedy these problems since I would think that these
>glazes had been calculated correctly, so that is not the problem.

>Thank you, Sandy Lindsey, Mystic CT

Muddy

Susan Goldstein on mon 3 may 99

I have a recipe that calls for Del Monte soda spar. Can F-4 or Custer be
substituted?

Thanks.

Susan

David Smith on thu 17 jun 99

I mixed 4000 grams of 60/40 volcanic ash/gertsley borate glaze with 3% zinc
and 4% tin oxide on February 28. I fired a dozen pieces the following
weekend and got a white gloss glaze I liked with my Standard 112 claybody.
This weekend I glazed another dozen pieces with the remainder of the glaze
and it came out clear..no white at all..identical to the straight 60/40
pieces I fired in the same load. The glaze was well mixed and sieved three
times before reusing. My assumption is that four months was too long to
store this glaze. Is this correct? What should the shelf life be for a
glaze of this type?

David
Weekend Potter

ginny bivaletz on thu 27 jan 00

we have been working with this ^10 mat glaze for a few
years. F4 feldspar 40
dolomite 30
epk 25
bone ash 5
add bentonite 2%

it goes on nicely at first but if sits in the bucket
for a month or so it begins to crack and flake off the
pot when it dries,especially in areas where it is
thick or if there is anothe glaze on top of it.
any ideas on this would be greatly appreciated as i
am mixing up glazes now for my first ^10 firing.
thanks ginny from orcas island
__________________________________________________
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Chris Schafale on fri 28 jan 00

Ginny,

I would start by leaving out the bentonite, which is probably
contributing to high shrinkage and glaze cracking. You've already
got a lot of clay in the recipe, which should be plenty to keep the
glaze suspended. That said, I also have this problem with glazes
that have more than about 15% clay. I'm anxiously awaiting what
folks have to say.

Chris

> ----------------------------Original message----------------------------
> we have been working with this ^10 mat glaze for a few
> years. F4 feldspar 40
> dolomite 30
> epk 25
> bone ash 5
> add bentonite 2%
>
> it goes on nicely at first but if sits in the bucket
> for a month or so it begins to crack and flake off the
> pot when it dries,especially in areas where it is
> thick or if there is anothe glaze on top of it.
> any ideas on this would be greatly appreciated as i
> am mixing up glazes now for my first ^10 firing.
> thanks ginny from orcas island
> __________________________________________________
> Do You Yahoo!?
> Talk to your friends online with Yahoo! Messenger.
> http://im.yahoo.com
>


Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
http://www.angelfire.com/nc2/candle (work in progress)

ferenc jakab on fri 28 jan 00

Ginny,
In another thread there has been a lot of discussion about wet mix or dry
mix. Well this is the best reason for dry mix and wet as you need it,
because some glaze materials are actually soluble over a period of time and
are no longer available in the glass suspension when you glaze your bisque
or green ware. I'm sure there are more complete answers available from
those more experienced with glazes than I, but this is what I remember from
my lectures at art school.
Feri.

martin howard on sat 29 jan 00

Chris says
I would start by leaving out the bentonite

I have used glazes with 20 percent fullers earth, which is bentonite or
montmorillonite. Similar substance. A very fine clay. The finest clay in
fact. Yes it has the name for shrinkage. I have a large 160 lawn sieved
container of it which is slowly drying in the kiln room. The canyon cracks
in it beat, in scale, the Grand Canyon several times over.

Yet, in glazes at 20 percent and at 10 percent, on a standard red clay
mixture specially for throwing, it never crazes.

It may have other properties which cause potters to warn against it, but in
my experience this crazing idea is just wrong, at least for me.

Martin Howard
Webb's Cottage Pottery
Woolpits Road
Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
www.webbscottage.co.uk Should be ready for 2000 :-) or 2001

Cindy Strnad on sat 29 jan 00

Ginny,

What Chris said about high clay content made me think that calcining some of
the EPK may also help you. I don't know why the glaze would change over
time, though. Still, it seems as if it might be worth a try.

Also, you can add CMC to harden your glaze, if you think hardening would
help. When you say it cracks and flakes off, that sounds to me as if you've
got the glaze on too thick, but I don't know what kind of effects you're
going for. Maybe you want it extremely thick for a reason. In that case, do
try the CMC. It should give you a more durable surface.

Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730

Dannon Rhudy on thu 28 dec 00

>
>I need to start out with a question. I had a recipe for a glaze called
>"perfect black," ....I have misplaced it...

Susan, there are numerous glazes called "Perfect Black".
What cone are you firing to, is the black gloss or matte?

regards

Dannon Rhudy

Susan Otter on thu 28 dec 00

In a message dated 12/28/00 5:37:40 PM, drhudy@PARIS.CC.TX.US writes:

<< >
>I need to start out with a question. I had a recipe for a glaze called
>"perfect black," ....I have misplaced it...

Susan, there are numerous glazes called "Perfect Black".
What cone are you firing to, is the black gloss or matte?

regards

Dannon Rhudy
>>


I think I said cone 10. The one I used was quite shiny. It's also markedly
stable -- maybe that's because it has so few ingredients, I don't know (I'm
just embarking on this glaze adventure).

What I want to do is throw a set of dishes (OK they're started) in porcelain.
Then I will glaze them with celadon (probably a green but I'm going to test
some recipes.

Then I want to use the black to add Chinese characters. I liked this glaze
because it stays right where you put it, and thick or thin gives consistent
results. In fact, it's so consistent that it could be tedious under different
circumstances (smile).

The place where I throw uses a gas kiln.

Earl Brunner on thu 28 dec 00

Sorry, you were probably thinking cone 10, but you didn't really SAY it,
see below.

People here do want to help, that's what many are here for, but they
sometimes find it frustrating when they don't have enough information.
As you have no doubt noticed from the replies so far, there are many
black glaze recipes out there and to compound the problem often the
names get changed as they get passed around, and people sometimes change
the recipes a little as they get passed around. The odds are really
against you finding the exact recipe you are looking for and even
knowing it is the right one without lots of testing.

You will probably find something eventually this way, but your best bet
is to get it from whoever you got it from originally.

A not of caution, many black recipes use a combination of Iron,
Manganese and Cobalt to get the black. Irons fairly safe and so is
Cobalt probably, there has been a lot of concern about manganese lately.
If you use a glaze with these colorants in them on a food surface you
need to know that it will be safe. You should get the glaze tested for
leaching.

Hi.

My name is Susan and I am an amateur intermediate potter hobbyist.

I take classes at Craft Alliance in St. Louis and I look forward to being
part of the listserv!

I need to start out with a question. I had a recipe for a glaze called
"perfect black," which I was given by another potter at Craft Alliance.

I have misplaced it. Does anyone have that glaze recipe?

Thanks to all in advance.


Susan Otter wrote:

> In a message dated 12/28/00 5:37:40 PM, drhudy@PARIS.CC.TX.US writes:
>
> << >
>
>> I need to start out with a question. I had a recipe for a glaze called
>> "perfect black," ....I have misplaced it...
>
>
> Susan, there are numerous glazes called "Perfect Black".
> What cone are you firing to, is the black gloss or matte?
>
> regards
>
> Dannon Rhudy
> >>
>
>
> I think I said cone 10. The one I used was quite shiny. It's also markedly
> stable -- maybe that's because it has so few ingredients, I don't know (I'm
> just embarking on this glaze adventure).

--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net

Barney Adams on sun 25 feb 01

Hi,
I'm working on some glazes and have a question. I've up graded my
Insight to 5.3.
I've been studing the mole% along side the RO unity. If I'm reading
correctly this
is the newer approach to limits. I am working on a stain base glaze and
trying to
compare it to Tony 's recipe in Magic Of Fire and I understand the need
for high
CaO. It seems that the value of CaO in Tony's glaze is over the limit
tables. I thought
that I read from Ron that CaO in high amounts can be detrimental to the
durablity of
a glaze. (or did I mis-read this?).
The limits from Insight are now referenced as targets. Is this also
following the Mole%
analysis for the target reference of Dr.Eppler? I'm not sure if I see a
way to connect the
limits I followed before to this new way, probably because there is no
connection. Is the "good"
approach to balance the Dr Eppler mole% with the limit tables. For
example: use mole% to
target the cone target and Al:Si ratio, but keep the Li2O within it's
limits?


One of the things that makes this glaze stuff so confusing is I hear or
read something from Ron
then something else from someone else that seems to conflict. When I
suspect that given the
context they probably all agree, it's just up to me to sort out the
context.

John Hesselberth on sun 25 feb 01

Hi Barney,

I will take a shot at a couple of your questions and mke a comment or two
below:

Barney Adams wrote:

>Hi,
>I'm working on some glazes and have a question. I've up graded my
>Insight to 5.3.
>I've been studing the mole% along side the RO unity. If I'm reading
>correctly this
>is the newer approach to limits.

Mole percentages can be just as informative as unity formulas. However
be absolutely sure you are looking a mole percentages. I know some of
the glaze calculation programs (including earlier versions of
Insight--don't know about 5.3--and HyperGlaze) calculate weight
percentages--not mole percentages. What is worse is that they don't make
that clear. Weight percentages are just about useless--in my opinion,
worse than useless. they can really confuse you--when you are thinking
about glaze stability. They can be helpful when you are looking at two
glazes that are very similar and want to compare one to the other.

I am working on a stain base glaze and
>trying to
>compare it to Tony 's recipe in Magic Of Fire and I understand the need
>for high
>CaO. It seems that the value of CaO in Tony's glaze is over the limit
>tables. I thought
>that I read from Ron that CaO in high amounts can be detrimental to the
>durablity of
>a glaze. (or did I mis-read this?).

As we learn more about glaze stabiliity, we are learning that stable
glazes can be made outside of limits. Specifically high calcium glazes
CAN be stable if the glaze is formulated with enough alumina and silica
and has fluxes plus boron that lets it melt. Also unstable glazes can be
made within limits. Staying within limits will PROBABLY give you a
relatively stable glaze. That is why Ron and others encourage people to
stay within them, particularly if they are relatively new to glaze
formulation.

I will propose a different way to think about all this in my NCECA talk
next month.

>The limits from Insight are now referenced as targets.

Limits have always been considered to be guidelines. They have never
been presented in the literature to be some kind of "law".

Is this also
>following the Mole%
>analysis for the target reference of Dr.Eppler? I'm not sure if I see a
>way to connect the
>limits I followed before to this new way, probably because there is no
>connection. Is the "good"
>approach to balance the Dr Eppler mole% with the limit tables. For
>example: use mole% to
>target the cone target and Al:Si ratio, but keep the Li2O within it's
>limits?

I'm not sure this will answer the questions directly above, but Eppler's
preference for mole percentages stems from the fact that they are a more
useful way to look at the composition for earthenware or low fire glazes.
The two methods are essentially equivalent at stoneware temperatures,
but earthenware glazes contain so much boron (which is traditionally not
included in unity) or lead that the unity numbers can be confusing or
misleading--especially when comparing a lead-based glaze to a lead free
one. You can make a strong case that boron should be included in unity
for earthenware glazes, but historically it has not been. And, to say it
again, make sure you really are using mole percentages, not weight
percentages.
>
>One of the things that makes this glaze stuff so confusing is I hear or
>read something from Ron
>then something else from someone else that seems to conflict. When I
>suspect that given the
>context they probably all agree, it's just up to me to sort out the
>context.

Part of that is because we are still learning. This is not hard, proven
science. It is mostly empirical observation and correlations of data.

Regards, John



"The life so short, the craft so long to learn." Hippocrates, 5th cent.
B.C.

Barney Adams on sun 25 feb 01

John,
That has cleared up a great deal. If I understand what you are saying below:

I should stay with the limits, but by studing the true Mole% (and understanding
what I'm studying) then I'd be able to expand on those limits with higher silica,
alumina and fluxes, but still melt the soup at the same cone and have a stable
glaze?

I should be able to test some glazes following the mole% to get the melt and having

the glaze tested to insure that I got it.

Thanks
Barney

John Hesselberth wrote:

> As we learn more about glaze stabiliity, we are learning that stable
> glazes can be made outside of limits. Specifically high calcium glazes
> CAN be stable if the glaze is formulated with enough alumina and silica
> and has fluxes plus boron that lets it melt. Also unstable glazes can be
> made within limits. Staying within limits will PROBABLY give you a
> relatively stable glaze. That is why Ron and others encourage people to
> stay within them, particularly if they are relatively new to glaze
> formulation.
>
> I will propose a different way to think about all this in my NCECA talk
> next month.

Marcia Selsor on sun 25 feb 01

Dear Barney,
I think you understand the mystique of ceramics. It is all relative
(again, I keep hearing "Grasshopper" in my mind). The ratio between the
Alumina to Silica determines the surface texture
1:10-15 crystal not necessarily macro crystalline but also iron reds, etc.
1:10 shiny
1:5 matt
The ratio between the fluxes (follow limits) and the silica determine
the cone. This is an old method , pre software programs.
Marcia in Montana




Barney Adams wrote:
>
> Hi,
> I'm working on some glazes and have a question. I've up graded my
> Insight to 5.3.
> I've been studing the mole% along side the RO unity. If I'm reading
> correctly this
> is the newer approach to limits. I am working on a stain base glaze and
> trying to
> compare it to Tony 's recipe in Magic Of Fire and I understand the need
> for high
> CaO. It seems that the value of CaO in Tony's glaze is over the limit
> tables. I thought
> that I read from Ron that CaO in high amounts can be detrimental to the
> durablity of
> a glaze. (or did I mis-read this?).
> The limits from Insight are now referenced as targets. Is this also
> following the Mole%
> analysis for the target reference of Dr.Eppler? I'm not sure if I see a
> way to connect the
> limits I followed before to this new way, probably because there is no
> connection. Is the "good"
> approach to balance the Dr Eppler mole% with the limit tables. For
> example: use mole% to
> target the cone target and Al:Si ratio, but keep the Li2O within it's
> limits?
>
> One of the things that makes this glaze stuff so confusing is I hear or
> read something from Ron
> then something else from someone else that seems to conflict. When I
> suspect that given the
> context they probably all agree, it's just up to me to sort out the
> context.
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.

--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/Tuscany2001.html
http://www.imt.net/~mjbmls/Gallery.html

Tony Hansen on mon 26 feb 01

>I think you understand the mystique of ceramics. It is all
>relative (again, I keep hearing "Grasshopper" in my mind).
>The ratio between the Alumina to Silica determines the
>surface texture
>1:10-15 crystal not necessarily macro crystalline but also iron reds, etc.
>1:10 shiny
>1:5 matt
>The ratio between the fluxes (follow limits) and the silica
>determine the cone. This is an old method , pre software
>programs.

If I might be so bold:

I think the ratio thing is pretty limited. Matte glazes are
often glossy glazes with a crystal mesh over the surface.
They defy the ratio system. Boron glazes (most glaze cone 6
and down have lots of boron) can be very glossy with very
high alumina contents. Glazes that have a low ratio can be
matte at one temperate and glossy at a higher temperature.
Middle and low fire glazes with a high ratio can be matte if
they have a high proportion of magnesia or zircon or other
refractory oxide that stiffens the melt and impedes the
development of a glassy smooth surface. It think the key to
understanding a matte is to understand why it is a matte,
its 'mechanism'. This is often not related to the Si:Al
ratio.

====================================================
T o n y H a n s e n thansen@digitalfire.com
D I G I T A L F I R E C O R P O R A T I O N
http://digitalfire.com Calculation/Database Software for Ceramic Industry

Howard Scoggins on mon 26 feb 01

I am researching Joseph Grebanier's Chinese
Stoneware Glazes (1975).
Mr. Grebanier was, judging from photos of his work,
an excellent potter. His glaze calculations are
cutting edge for the time .

My question: anyone out there who has tried any of
his glazes? I would like to query anyone who is
familiar with his work.

Howard Scoggins

Ron Collins on tue 14 aug 01

This is such a basic response, but I'll tell you what is working for
me...someone on clayart posted a low fire clear of 60% frit 3134 and 40%
ball clay-I have been using OM4. It works like a charm, brushes well, and
most importantly does not craze on my clay body like some other things I've
tried. It works well to add tin or zircopax, colorants, ochers, etc. It is
a very good place to start. while it is listed as a cone 04, it goes a lot
higher very nicely. Elegantly simple with great results-for me....Melinda
Collins in Guatemala

Wildseed on tue 14 aug 01

I have been offlist for a long time and this may be old territory, so
apologies in advance. I am looking for reliable glaze recipes for 03
firings in an electric kiln. I want a good base glaze that I can color.
Must be dinner safe, not a "high gloss" type, and suitable for dipping or
pouring. I use white low fire clay (Standard Supply #103) and terracotta
(Standard Supply #417). Any help or redirection to a good resource would be
greatly appreciated. Trying to make the mortgage payments in Florida and
reduce a portion of the trial and error time. Thanks

Ababi on wed 15 aug 01

Hello Wild seed!
Go to http://art.sdsu.edu/ceramicsweb/
the other side of the USA
Look for Class Materials and Education
there
Articles on a variety of ceramic topics
Majolica & Lowfire Recipes

My tip: add colorant I like to add to my base, which has ultrox 4-6 copper
oxide. Foodsafe?
Apply outside
If you feel soft use tin and less colorant.
I cannot offer my glazes you don't have the right frits
Ababi Sharon
ababisharon@hotmail.com
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/

----- Original Message -----
From: "Wildseed"
To:
Sent: Tuesday, August 14, 2001 11:08
Subject: Re: Glaze question


> I have been offlist for a long time and this may be old territory, so
> apologies in advance. I am looking for reliable glaze recipes for 03
> firings in an electric kiln. I want a good base glaze that I can color.
> Must be dinner safe, not a "high gloss" type, and suitable for dipping or
> pouring. I use white low fire clay (Standard Supply #103) and terracotta
> (Standard Supply #417). Any help or redirection to a good resource would
be
> greatly appreciated. Trying to make the mortgage payments in Florida and
> reduce a portion of the trial and error time. Thanks
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>

Anj Campbell on thu 6 sep 01

I have recently tested the following glazes:

Veronica Shelford's Oatmeal Satin ^6

38 Custer feldspar
6 dolomite
5 whiting
9 kaolin
13 silica
18 Gerstley borate
12 talc
4 zircopax
4 titanium (reduced to 2 titanium)
added to original recipe: 4 rutile
2 granular ilmenite

Ron Roy's revision of Xavier's Warm Jade ^6

22 Custer feldspar
16 Ferro frit 3134
12 whiting
9 talc
20 EPK
21 silica
3 copper carbonate
5 rutile

Fired electric with ^6 in the kiln sitter, and a one
hour soak on low after the sitter has shut off.

On Standard Ceramics' 112 tan clay, the oatmeal satin
is a well behaved creamy, bright satin-to-gloss smooth
surface. It variegates other glazes nicely, but
remains a fairly uniform color on its own.
On Standard's 213 porcelain, the color shifts to a
pale butterscotch gold gloss with floating
rutile-variegated patches in pale oatmeal.
On Standard's 308 Brooklyn Red, the color shifts to a
distinct though pale blue, with beautiful "hares' fur"
variegation. It's a beautiful color and effect, but it
isn't OATMEAL!

A similar color change occurs with the RRRvXWJade--on
porcelain, a pleasant muted green; on 112, a
greenish-blue with moderate variegation, and on 308, a
medium blue with much more variegation.

I am not unhappy with the results--the blue from RR's
jade revision is stunning. It has something of the
same "feel" that Floating Blue at its best achieves,
though the color is a lighter blue. And the Shelford
Oatmeal opalesces beautifully...

The effect is reproducible--two different test batches
of both glazes in three different firings yield the
same results.

My question is WHY is the color change so pronounced
from clay to clay? Is the rutile interacting with the
iron in the red clay body to produce the blue tones? I
have checked Rhodes, Fraser, Nelson, and the archives
to no avail. The information I have found on "rutile
blue" involves reduction firing and a specific
aluminum-silica ratio, which does not seem to fit this
situation. I'd just like to understand the "why" of
this for future reference.

Thanks in advance for any help,

Anj Campbell

__________________________________________________
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Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger
http://im.yahoo.com

Kathleen Schultz on sun 7 oct 01

I would like to fuse two pieces together with a colemanite glaze fired to
cone 6 in oxidation, using Standard's clay #112. The base is a container for
lamp oil and must be glazed inside. The top piece is a shallow bowl with a
small hole for the wick, going through a clay bead. Would the glaze fuse it
together in firing? Should both pieces be glazed, or only one of the pieces?
Or should I just use an epoxy like E-6000 to fuse the pieces after firing?
Thanks for your help!

Cindy Strnad on sun 7 oct 01

Kathleen,

If the pieces are touching, they'll fuse. I'd just
go ahead and glaze both and then set the bowl
carefully on the stand. If you want the seal to be
water/oil tight, the surfaces will have to match
perfectly to begin with. Silicone caulking won't
fix any holes that the glaze may leave, either, if
you're filling with lamp oil. I tried that on a
leaky metal lamp. Doesn't work. Don't bother.

Hope it turns out great!

Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com

David Hendley on sun 7 oct 01

Glazing separate pieces together is much better than gluing
them together after firing.
I regularly glaze the threaed clay collar on the top of lotion
jars in this way. Just remember that the top piece must be
sitting on a perfectly level surface, or it might slide off its
intended spot when the glaze is molten.
Either one, or both of the pieces can be glazed. A thin
coating on both is best.
In my tests, the glazed-together pieces are absolutely
bonded together; the jar will break before the collar can
be broken off.

David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com

----- Original Message -----
From: Kathleen Schultz
To: CLAYART@LSV.CERAMICS.ORG
Sent: Sunday, October 07, 2001 3:41 PM
Subject: Glaze question


I would like to fuse two pieces together with a colemanite glaze fired to
cone 6 in oxidation, using Standard's clay #112. The base is a container
for
lamp oil and must be glazed inside. The top piece is a shallow bowl with a
small hole for the wick, going through a clay bead. Would the glaze fuse it
together in firing? Should both pieces be glazed, or only one of the
pieces?
Or should I just use an epoxy like E-6000 to fuse the pieces after firing?
Thanks for your help!

mel jacobson on fri 11 jan 02

>From: "Eddie and Sue Michael"
>To:
>Subject: glaze problem
>Date: Fri, 11 Jan 2002 10:20:25 -0500
>X-Mailer: Microsoft Outlook Express 5.00.2919.6600
>this was on my computer.

don't know what to say.
a private email to her...perhaps.
someone that does commercial...stuff.

>Dear Sir:
>
>I found you name as moderator on Clayart message board, and was not quite
>sure how to get a question on it. I tried to register and I got an email
>back from the University of Kentucky unknown command. So I thought I
>would just email you and see if you could help me.
>
>I make ornaments and when I glaze for example a white westie dog, it
>sometimes comes out with green specs on it. They look like underglaze,
>but they don't show up on all of them, but a lot of them.
>
>I have cleaned and kiln washed all my kilns and shelves, I have changed my
>clear glaze bucket, and kept my brushes and water cleaned out, but they
>are still showing up. Would you have any idea what is causing this?
>
>If you have any insight I would surely appreciate it. Our spring show is
>coming up soon and I can't afford to have to remake these guys three and
>four times to get them right.
>
>Thank you!
>
>Sue Michael

From:
Minnetonka, Minnesota, U.S.A.
web site: http://www.pclink.com/melpots

Michael Sowers on sat 12 jan 02

Sounds like iron contamination in the clay causing spots of "celadon" in the
clear glaze. I know if I get any contamination of the porcelain from my
stoneware or from rust it will show up as greenish spots under a translucent
or clear glaze, dark green spots when I use my celadon glaze. The
contamination would be so slight as to not show up or bleed through other
glazes. Just a thought.

Michael Sowers
Classic Lines Pottery
www.classiclinespottery.com/

>I make ornaments and when I glaze for example a white westie dog, it
>sometimes comes out with green specs on it. They look like underglaze,
>but they don't show up on all of them, but a lot of them.
>
>I have cleaned and kiln washed all my kilns and shelves, I have changed my
>clear glaze bucket, and kept my brushes and water cleaned out, but they
>are still showing up. Would you have any idea what is causing this?

Snail Scott on sat 12 jan 02

>>...sometimes comes out with green specs on it.

At 05:45 AM 1/12/02 -0800, Michael wrote:
>Sounds like iron contamination in the clay causing spots of "celadon" in the
>clear glaze.


Do any of your tools have rust on them that
might be flaking off?

-Snail

Valice Raffi on sun 13 jan 02

>>>...sometimes comes out with green specs on it.
>
>At 05:45 AM 1/12/02 -0800, Michael wrote:
>>Sounds like iron contamination in the clay causing spots of "celadon" in the
>>clear glaze.

you mentioned that you're making Christmas ornaments and "westie dogs", are
they molded? In some of the places I've taught, we've shared studio space
with the people who use molded ware. Many shipments of the greenware
contained iron specks. I suspect they either came from very old mixing
equiptment (rust flaking), or poor cleaning practices after mixing a red
clay. Check out your supplier.

Valice
in Sacramento

Andi Fasimpaur on sun 13 jan 02

At 04:28 PM 1/11/02 -0600, Mel forwarded:
>>From: "Eddie and Sue Michael"
>>To:
>>Subject: glaze problem
>>Dear Sir:
>>
>>I make ornaments and when I glaze for example a white westie dog, it
>>sometimes comes out with green specs on it. They look like underglaze,
>>but they don't show up on all of them, but a lot of them.
>>
>>I have cleaned and kiln washed all my kilns and shelves, I have changed my
>>clear glaze bucket, and kept my brushes and water cleaned out, but they
>>are still showing up. Would you have any idea what is causing this?

You don't mention whether you are suspending your
ornaments to fire them or if you are firing them flat. If
you're firing them flat, directly on the kiln shelf, just
using fresh kiln wash should have helped... do you
notice that the ornaments in some places in the kiln
are more likely to be effected than in others (ie, those
close to the sides/elements) I noticed that the elements
in one of the kilns at an art center where I was working
were flaking, they'd been contaminated by something
and whatever it was kept flaking off and floating around
the kiln... it might at least help you to track down the
problem zones, maybe you can put green ornaments
there until you change the elements (if that's the
source of your problem)

I fire pendant bottles, beads, mermaids, etc suspended
from bead wire, sometime of the wires that I have, I
think that maybe some stainless welding rods got
mixed in with my bead wires at some point, the wires
flake a little and I get little dark specks, since its been
a while since it happened, I can't remember if they're
green or not, but maybe that's another possible
explanation... maybe the wire you're using to suspend
the ornaments is the culprit...

Good luck,

Andi Fasimpaur
http://www.mysticspiral.com

ps, I'm posting this to clayart as well as sending it
privately, in case anyone on the list is having a
similar problem...

Bill Edwards on sat 23 aug 03

While I do a bit of calculations I seen something that
I have little knowledge of and would like to
experiment some. I have seen what looks like slip
trailed glaze which is very glossy and stands up under
firing without melting to the point of sliding or
leveling out upon firing. I understand the under-glaze
would play a role here but I can't find or didn't find
any information in the archives on what this may be
called?
The one I seen was a clear blue cobalt which looked
almost like a glass slip trailed line over a
light/white glaze body. It was transparent and defined
as if it was put on with a pen or some form of
injection such as a syringe. It was on a cone 6
oxidation piece as well.
Can anyone lead me to a starting point on this and
what this is called? A guru would be a great find
right about now, in particular on this subject.
It would have to be some form of slip? What kind and
how is it made? A starting point is all I need.

Bill Edwards

=====
http://www.tallapoosariverpottery.com/

Bill Edwards
PO Box 267
Lafayette, AL, 36862

__________________________________
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Paul Lewing on sun 24 aug 03

on 8/23/03 10:26 PM, Bill Edwards at wgedwards2001@YAHOO.COM wrote:

> The one I seen was a clear blue cobalt which looked
> almost like a glass slip trailed line over a
> light/white glaze body. It was transparent and defined
> as if it was put on with a pen or some form of
> injection such as a syringe. It was on a cone 6
> oxidation piece as well.
> Can anyone lead me to a starting point on this and
> what this is called? A guru would be a great find
> right about now, in particular on this subject.
> It would have to be some form of slip? What kind and
> how is it made? A starting point is all I need.

Bill, one starting point would be the notion that there is a continuum from
slip to glaze. So start with a blue slip and blend in flux. Or start with
a blue glaze and add clay. Either way you should at some point get a
substance that is glossy but will hold its shape on your work.

Paul Lewing
God- no way!
Guru- maybe.
Artist- you bet!

Craig Martell on sun 24 aug 03

Hello Bill:

I don't know if this is exactly what you've seen and are interested in
reproducing, but I've seen and done glassy, raised, trailed lines with pure
feldspar with some added bentonite or macaloid. You can add colorants as
desired. Try a test and see if this is what you are after. I think either
Custer or G-200 would be OK. I use Clairol hair color bottles for trailing.

regards, Craig Martell Hopewell, Oregon

Tony Hansen on sun 24 aug 03

I saw this done at a huge tile factory in Turkey.
They screen printed glue in the desired parttern
onto the fired glaze surface and and sprinkled a
granular transparent burning frit onto them.
The chemistry, mechanical, firing and application
complexities of getting this working would
be daunting on tile let along on vertical surfaces.

-------8<--------
While I do a bit of calculations I seen something that
I have little knowledge of and would like to
experiment some. I have seen what looks like slip
trailed glaze which is very glossy and stands up under
firing without melting to the point of sliding or
leveling out upon firing. I understand the under-glaze
would play a role here but I can\'t find or didn\'t find
any information in the archives on what this may be
called?
The one I seen was a clear blue cobalt which looked
almost like a glass slip trailed line over a
light/white glaze body. It was transparent and defined
as if it was put on with a pen or some form of
injection such as a syringe. It was on a cone 6
oxidation piece as well.
Can anyone lead me to a starting point on this and
what this is called? A guru would be a great find
right about now, in particular on this subject.
It would have to be some form of slip? What kind and
how is it made? A starting point is all I need.

Bill Edwards

=====
http://www.tallapoosariverpottery.com/

Bill Edwards
PO Box 267
Lafayette, AL, 36862

__________________________________
Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software
http://sitebuilder.yahoo.com

______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.


--------
Tony Hansen, Digitalfire Corp.

Earl Krueger on mon 25 aug 03

On Saturday, August 23, 2003, at 11:26 PM, Bill Edwards wrote:

> I have seen what looks like slip
> trailed glaze which is very glossy and stands up under
> firing without melting to the point of sliding or
> leveling out upon firing.

I'm no expert here but could this be borax with a little cobalt in it,
applied over an already fired glaze, and then fused at a low
temperature? Is fused borax soluble? I don't know. Just a thought.

Earl...

Tjo62@AOL.COM on tue 4 nov 03

I have a glaze I use with students that is supposed to be a cone 6 glaze but
it actually likes 7 or even 8 better. I have already mixed a big bucket and
would like to use it at 6. Could I add, say 8% Gerstley?

Ababi on tue 4 nov 03

Yes you can try, it might help.
Perhaps try with a small amount first. If you have lets say 10 litters
or OZ with the water stir well and add to one tenth in weight or in
volume 5-10% GB if you like the results go on. In any case you may send
me the recipe and I may be able to help easier.

Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm



-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of
Tjo62@AOL.COM
Sent: Tuesday, November 04, 2003 3:02 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: glaze question

I have a glaze I use with students that is supposed to be a cone 6 glaze
but
it actually likes 7 or even 8 better. I have already mixed a big bucket
and
would like to use it at 6. Could I add, say 8% Gerstley?

________________________________________________________________________
______
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Ron Roy on wed 5 nov 03

If you send me the recipe I can confirm or make an adjutment - when and
from whom did you buy the Gers Borate?

RR

>I have a glaze I use with students that is supposed to be a cone 6 glaze but
>it actually likes 7 or even 8 better. I have already mixed a big bucket and
>would like to use it at 6. Could I add, say 8% Gerstley?

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Tjo62@AOL.COM on wed 5 nov 03

I purchased the GB 5 yrs ago. My glazes are cone 9-10, so I don't use it
often. I do mix cone 5-6 with students, but I have been using Laguna Borate with
those glazes, except one called Randy's Red (uses spanish RIO). It is just
not the same with the Laguna Borate--has a floating red, speckled surface with
GB and just a dull (no depth) brown surface with LB. So, I did just buy a bag
of what is supposed to GB from Bailey. When it came, yesterday, the bag said
Laguna on the side, but Gerstley Borate on the bottom. I ordered it online
especially for the one recipe. I think I'll call them today and make sure exactly
what it is. I hear there is another good substitute from Axner. What do you
recommend as the best one? Thanks for your response to my other question and I
will get you that recipe this evening. Tonya in Louisville, KY

Kat on wed 5 nov 03

Tjo62@AOL.COM wrote:

>Subject: glaze question
>I have a glaze I use with students that is supposed to be a cone 6 glaze but
> it actually likes 7 or even 8 better. I have already mixed a big bucket and
>would like to use it at 6. Could I add, say 8% Gerstley?


Do you mind posting the recipe?

Kat
kat@digitalfire.com

Tony Hansen on wed 5 nov 03

Check www.gerstleyborate.com
I use this Randys Red and use Boraq and it works great.

-------8<--------
I purchased the GB 5 yrs ago. My glazes are cone 9-10, so I don\'t use it
often. I do mix cone 5-6 with students, but I have been using Laguna Borate with
those glazes, except one called Randy\'s Red (uses spanish RIO). It is just
not the same with the Laguna Borate--has a floating red, speckled surface with
GB and just a dull (no depth) brown surface with LB. So, I did just buy a bag
of what is supposed to GB from Bailey. When it came, yesterday, the bag said
Laguna on the side, but Gerstley Borate on the bottom. I ordered it online
especially for the one recipe. I think I\'ll call them today and make sure exactly
what it is. I hear there is another good substitute from Axner. What do you
recommend as the best one? Thanks for your response to my other question and I
will get you that recipe this evening. Tonya in Louisville, KY

_____________________________________________________________________________
-------
Tony Hansen, http://digitalfire.com
Personal Contact Page: http://digitalfire.com/services/contact.php
Calculation/Database Software for Ceramic Industry

Ron Roy on thu 6 nov 03

Hi Tonya,

I do know Laguna does have some GB available but they don't have an
analysis for it so we cannot know how it compares to the material from the
past. There was some that certainly did not melt as well.

The Gillespie Borate seems to be closest to the original GB - you will have
to try some to tell if it will work the way you want it to.

RR

>I purchased the GB 5 yrs ago. My glazes are cone 9-10, so I don't use it
>often. I do mix cone 5-6 with students, but I have been using Laguna
>Borate with
>those glazes, except one called Randy's Red (uses spanish RIO). It is just
>not the same with the Laguna Borate--has a floating red, speckled surface with
>GB and just a dull (no depth) brown surface with LB. So, I did just buy a bag
>of what is supposed to GB from Bailey. When it came, yesterday, the bag said
>Laguna on the side, but Gerstley Borate on the bottom. I ordered it online
>especially for the one recipe. I think I'll call them today and make sure
>exactly
>what it is. I hear there is another good substitute from Axner. What do you
>recommend as the best one? Thanks for your response to my other question and I
>will get you that recipe this evening. Tonya in Louisville, KY

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Sheron Roberts on sat 1 may 04

I have been puzzling over a glaze I mixed,
and maybe some of you can enlighten me
a bit. The glaze is Conrad G375 Moonlight Blue.
I did not have powdered Ilmenite, so I used the
granular, resulting in a very nice creamy blue
with little brown speckles. Some of the speckles
have halos of gold. Very pretty. The only thing
I didn't like was in some places the grains of
Ilmenite left the surface a bit rough. A potter
friend of mine gave me enough powdered Ilmenite
to try the glaze as it was originally formulated.
This batch came out predominately honey colored
with a few streaks of seafoam blue, (totally differant
blue than the first batch) where the glaze
was thicker. The only difference between the two
batches was the Ilmenite, and I had run short on the
Cornwall Stone, so I ordered more. In other words,
the Cornwall Stone came from two differant sources.
Both batches were fired to cone 8 oxidation.
I guess the basic question is, would the color be
that different because of powdered Ilmenite versus
granular Ilmenite?
Sheron in NC

Cornwall Stone 63.8
Gersley Borate 14.3 (used substitute)
Silica 7.6
Whiting 7.6
EPK 4.8
Zinc Oxide 1.9

Rutile 3.2
Ilmenite 2.0
Cobalt Carbonate 0.5

Paul Herman on sat 1 may 04

Sheron,

In answer to the question below, a definite yes.

The powdered stuff is dispersed and mixed with the other ingredients,
the grains are not.

good glazing,

Paul Herman

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

----------
>From: Sheron Roberts
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: glaze question
>Date: Sat, May 1, 2004, 8:26 AM
>

> I guess the basic question is, would the color be
> that different because of powdered Ilmenite versus
> granular Ilmenite?
> Sheron in NC

Sheron Roberts on wed 12 may 04

Thanks to all who helped answer my question about
Ilmenite. I am a little slow with the thanks, due to
a sudden change in my health. Boy, can things=20
change in a hurry! Seems I may possibly have
a heart blockage. After two weeks of extreme
fatigue and feeling as though I had a boa constrictor
hugging me, I went to my family doctor. When he
saw the readout from the EKG he literally jumped
in his chair. So I have to do the stress test thing
and then I am not sure what we will do from there.

I really became aware of a problem when I rolled
up 10 3 pound balls of clay and was completely
fatigued after throwing 4 of them.

Thanks again, guys, for the info and I will put
it to good use, when I get the ticker fixed.

Sheron in NC
(bored out of my tree, no driving, no clay,=20
no household chores....)

daniel on wed 15 sep 04

Hi Neal,

There are others here better qualified to address this, but I'll take a
shot as I ran some numbers on your glaze.

First thing is that I assumed that you used custer as your feldspar. If
this is not true then let me know. I looked up the 5x 20 on Tony's site.
Secondly I use Ron Roy's MDT in Insight rather than the standard one
supplied with Insight. You can download it from Tony's site.

Adding the cobalt and rutile make the problem slightly worse actually,
rather than better. I have not tried this glaze but it is often the case
that colourants can make it difficult to see craze lines. Use a felt tip pen
to draw on the glaze and then wash it off. The colour will stick in the
cracks if there are any.

As to the crazing, its a mismatch between the expansion of your clay and
the glaze, the glaze being too high. I guess you already know this. The
numbers I get indicate that that crazing on my clays would be likely, but I
do not know Desert Buff. Honestly, to fix this problem really properly and
to understand it in detail so that you can develop future glazes for your
clay, I would recommend Mastering Cone 6 Glazes chapter 5. It gives a full
explanation of the problem and how to determine what will work on your clay.
It also gives a couple of clear base glazes. I had a quick look at
Highwater's online catalog and they do not state an expansion for this clay.

In my calcs. adding the silica did not make that much difference once the
rutile was added in. So you may have added enough silica and you may not.
The thing I'm doing at the moment at ^ 10 to solve the same problem is
running a blend of a low expansion glaze with a regular clear to see what
works. That would help you a lot here too.

One other thing. Unless you have a reason for all that CaO - Tony gives
some - its got a high expansion and it is pushing the expansion up. Raising
the silica will raise the temperature of the glaze a bit. It seems your
version will still melt at cone 6, but it may not fix the crazing. Talc is
an option, if you don't go nuts with it, and will help the expansion.
Perhaps a little of both will give you what you want. If you want I can send
you a variation or two to get you started if you tell me exactly what your
recipe was.

Ultimately, this task may take a few goes round.

Hope this helps.
Daniel

Belmont, California, USA
(ex terra australis)

Neal on wed 15 sep 04

I fired my first glaze firing (cone 6) in my new kiln (L&L
EasyFire e28s) this past weekend. I made small (500 g)
batches of Tony Hansen's 5x20 glaze to try on a few pieces
of Highwater Desert Buff but glazed most of the pieces with
glazes mixed up at one of the city arts centers (since my
other clay came from there).

I used the clear glaze on some flat tiles. A couple of mugs
had the variegated blue variation. When the kiln cooled and
I unloaded it, everything looked great. Now, a few days
later, I noticed that the tiles are crazing. The glaze on
the blue mugs doesn't look like it's crazing--yet.

In my novice approach, I went ahead and made a large batch
(5,000 g) of the variegated blue glaze. Now I wonder if it
will craze eventually. In searching through the archives, I
found that crazing gets discussed a bunch. Wallace Myers
had the same results as me when he tried the 5x20 clear
glaze. I tried writing him to see if he followed the
suggestions and if anything worked for him, but that email
address for him doesn't work any more and I did not see him
active on the list still.

A few things that were suggested then were decreasing the
custer feldspar, increasing the silica, and adding talc.

I'm already planning on making really small (100 g) test
batches of more glazes to try in my next firing. But I have
pieces that need to be glazed and fired along with the
tests. My options seem to be using the blue glaze as is or
trying to tinker with it before using it.

One of my ideas was just to increase the amount of silica
by adding 263 more grams. That would reduce the thermal
expansion from 7.03 to 6.86 and increase the Si:Al from
9.65 to 10.46. (I got these numbers from Insight 5.4. I've
read a bunch of the manual, but am way over my head here.)

Any thoughts?

Neal




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John Hesselberth on thu 16 sep 04

On Wednesday, September 15, 2004, at 02:40 PM, Neal wrote:

> A few things that were suggested then were decreasing the
> custer feldspar, increasing the silica, and adding talc.

Hi Neal,

The short answer is that you can decrease the tendency to craze by
doing any of the above things. It's great that you are trying to
understand what you are doing by beginning to use glaze calculation as
a tool. You will find after a few tries the answer to this kind of
question will come really easily.

I too used to use 5x20, but was dissatisfied with the stability
(ability to hold copper)--it is good, but I wanted better. I also
wanted a little lower COE. That glaze evolved to Glossy Base 1 in Ron's
and my book Mastering Cone 6 Glazes. If you want a fully tested variant
that might solve your problem check that one out.

Regards,

John

John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com

Bonnie Staffel on fri 17 sep 04

I did a lot of tests for a clear glaze trying to solve the crazing problem.
My final analysis showed that you have to apply it thin, thin, thin. My
last batch I made with the glaze about the texture of skim milk. Popped the
pot in and out. That glaze is so beautiful and satiny, rather than a harsh
shine. I fire at Cone 9 to 3 o'clock. One thing we changed was the grind
of the Flint to use the finest available.

If your glaze seems to craze especially where thicker, such as at the bottom
of the pot or any gathering site on the pot, you might try the thinner
application.

Warm regards,

Bonnie Staffel
http://webpages.charter.net/bstaffel
http://www.vasefinder.com/
Potters Council member

Kate Johnson on sat 18 sep 04

Bonnie wrote:

>I did a lot of tests for a clear glaze trying to solve the crazing problem.
> My final analysis showed that you have to apply it thin, thin, thin. My
> last batch I made with the glaze about the texture of skim milk. Popped
> the
> pot in and out. That glaze is so beautiful and satiny, rather than a
> harsh
> shine. I fire at Cone 9 to 3 o'clock. One thing we changed was the grind
> of the Flint to use the finest available.

Which brought up a question relating to my work--as I said, some of what I
do is early style redware, and the really shiny clear glaze just doesn't
look right. Still needs to be food safe, though--so would thinning the
glaze this much be a solution, perhaps? I really would prefer a more satin
and also a thinner effect...

Having a great deal of fun researching and attempting
reproductions/"historically inspired" pieces at the moment. Using the same
technology I tried out for the small rectangular flasks, I made a round
canteen similar to original 18th C. stuff, and several trenchers and pie
plates, all decorated with various types of slip decoration. One will be
sgraffitoed today...thanks toall who offered resource suggestions.


Kate Johnson
Graphics/Fine Arts
http://www.cathyjohnson.info/
http://www.epsi.net/graphic/

Ron Roy on sat 18 sep 04

Hi Neal,

There is quite a difference in expansion/contraction between the Hansen and
the variegated blue glaze - the blue being much lower.

I suggest you either use the fit testing glazes in chapter 5 to find out
the ideal expansion for glazes to fit on the clay you are using - or - do a
line blend of the Hansen and blue glaze to find out when the crazing stops.

Once you know the right calculated expansion for that clay - you can adjust
glazes to fit properly.

The fact that the crazing did not show up for a number of days means that
glaze can be adjusted easily to not craze.

Try this revision.

Custer - 12.0 (G200 will work)
Wolastonite - 18.0
Frit 3134 - 24.0
EPK - 23.0
Silica - 23.0
Total - 100.0

It will still be a stable glaze.

RR

>I fired my first glaze firing (cone 6) in my new kiln (L&L
>EasyFire e28s) this past weekend. I made small (500 g)
>batches of Tony Hansen's 5x20 glaze to try on a few pieces
>of Highwater Desert Buff but glazed most of the pieces with
>glazes mixed up at one of the city arts centers (since my
>other clay came from there).
>
>I used the clear glaze on some flat tiles. A couple of mugs
>had the variegated blue variation. When the kiln cooled and
>I unloaded it, everything looked great. Now, a few days
>later, I noticed that the tiles are crazing. The glaze on
>the blue mugs doesn't look like it's crazing--yet.
>
>In my novice approach, I went ahead and made a large batch
>(5,000 g) of the variegated blue glaze. Now I wonder if it
>will craze eventually. In searching through the archives, I
>found that crazing gets discussed a bunch. Wallace Myers
>had the same results as me when he tried the 5x20 clear
>glaze. I tried writing him to see if he followed the
>suggestions and if anything worked for him, but that email
>address for him doesn't work any more and I did not see him
>active on the list still.
>
>A few things that were suggested then were decreasing the
>custer feldspar, increasing the silica, and adding talc.
>
>I'm already planning on making really small (100 g) test
>batches of more glazes to try in my next firing. But I have
>pieces that need to be glazed and fired along with the
>tests. My options seem to be using the blue glaze as is or
>trying to tinker with it before using it.
>
>One of my ideas was just to increase the amount of silica
>by adding 263 more grams. That would reduce the thermal
>expansion from 7.03 to 6.86 and increase the Si:Al from
>9.65 to 10.46. (I got these numbers from Insight 5.4. I've
>read a bunch of the manual, but am way over my head here.)
>
>Any thoughts?
>
>Neal
>
>
>
>
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Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

daniel on sat 18 sep 04

Hi Ron, Neal,

I'm a bit confused here.

I looked at Tony's 5 x 20 and then added the 5% rutile and 0.2% cobalt he
suggests for a varigated blue variation (which is what I thought you were
using Neal ? ) and I got a higher expansion. Given the expansion of rutile
I'm puzzled how the expansion could be lower. Or are you talking about the
MC6G Variagted Blue base ?

Just trying to get this straight in my head.

> There is quite a difference in expansion/contraction between the Hansen and
> the variegated blue glaze - the blue being much lower.
>

Thanx
D

Belmont, California, USA
(ex terra australis)

Ron Roy on mon 20 sep 04

Hi Kate,

Adding clay will cut the shine down and lower expansion.

Doa line blend adding 1% clay to the recipe for #1 and 5% for #5.

Equal parts by volume of #1 and 5 gives #3
Equal parts of #1 and #3 gives #2
3 and 5 gives # 4.

Or send me the recipe and I will give you some to try but describe the
crazing - fine, large, delayed - like that.

RR


>>I did a lot of tests for a clear glaze trying to solve the crazing problem.
>> My final analysis showed that you have to apply it thin, thin, thin. My
>> last batch I made with the glaze about the texture of skim milk. Popped
>> the
>> pot in and out. That glaze is so beautiful and satiny, rather than a
>> harsh
>> shine. I fire at Cone 9 to 3 o'clock. One thing we changed was the grind
>> of the Flint to use the finest available.
>
>Which brought up a question relating to my work--as I said, some of what I
>do is early style redware, and the really shiny clear glaze just doesn't
>look right. Still needs to be food safe, though--so would thinning the
>glaze this much be a solution, perhaps? I really would prefer a more satin
>and also a thinner effect...
>
>Having a great deal of fun researching and attempting
>reproductions/"historically inspired" pieces at the moment. Using the same
>technology I tried out for the small rectangular flasks, I made a round
>canteen similar to original 18th C. stuff, and several trenchers and pie
>plates, all decorated with various types of slip decoration. One will be
>sgraffitoed today...thanks toall who offered resource suggestions.
>
>
>Kate Johnson

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Ron Roy on mon 20 sep 04

Hi Daniel,

I am wrong - I thought Neal was talking about our varigated blue.

Thanks Daniel - RR

>Hi Ron, Neal,
>
> I'm a bit confused here.
>
> I looked at Tony's 5 x 20 and then added the 5% rutile and 0.2% cobalt he
>suggests for a varigated blue variation (which is what I thought you were
>using Neal ? ) and I got a higher expansion. Given the expansion of rutile
>I'm puzzled how the expansion could be lower. Or are you talking about the
>MC6G Variagted Blue base ?
>
> Just trying to get this straight in my head.
>
>> There is quite a difference in expansion/contraction between the Hansen and
>> the variegated blue glaze - the blue being much lower.
>>
>
>Thanx
>D

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Kate Johnson on tue 21 sep 04

Hi Ron--

> Hi Kate,
>
> Adding clay will cut the shine down and lower expansion.
>
> Doa line blend adding 1% clay to the recipe for #1 and 5% for #5.
>
> Equal parts by volume of #1 and 5 gives #3
> Equal parts of #1 and #3 gives #2
> 3 and 5 gives # 4.
>
> Or send me the recipe and I will give you some to try but describe the
> crazing - fine, large, delayed - like that.

Thank you! Actually, I think two posts got put together--it wasn't me who
was having trouble with crazing, but with shinier-than-I want glazes, so
will try the adding a bit of clay idea.

I'm working with terra cotta clay and making historically inspired
redware...at this point, using commercial transparent glaze that we have at
school. For the most part I want to be very careful not to change the color
or intensity of the folk-art style slip decoration, so will need to be
careful with how much clay I add, I'd think. I'll do a test tile, as you
suggest...

I used a thinned glaze on one of my small green man sculptures and wasn't
happy with the result, for him, but it might be fine for the
dishes/bakeware. Ah, experimentation!

Best--
Kate

Tom Sawyer on tue 23 jan 07

I have two glazes that I layer; the bottom glaze is very powdery and when
the top glaze is put on top there is a great deal of cracking and flaking.
When fired the combination is breath taking. 1. What is the cause? 2. is
there any easy correction? Thanks for any constructive comments.



Tom Sawyer

Snail Scott on wed 24 jan 07

At 09:55 AM 1/23/2007 -0500, you wrote:
>I have two glazes that I layer; the bottom glaze is very powdery and when
>the top glaze is put on top there is a great deal of cracking and flaking...


Try adding CMC or bentonite to the
bottom glaze, to make a harder surface.

-Snail

Stephanie Wright on wed 24 jan 07

Hi Tom,

There are some more things we would need to know for anyone on the list to
help you.

First, and most importantly, what are your glaze ingredients, in what
amounts?

Secondly, are you talking about cracking and flaking of your glazes before
or after you fire them? If after, what temperature are you firing at?

I would say, in my opinion, the best person on the list to help you with
this would be Ron Roy.

Possible theory about your problem - if you are having problems with
cracking and flaking BEFORE final firing, maybe you are not bisquing at a
high enough temperature. You might have extra moisture, or something else
left in the clay that is keeping your glaze from sticking to the pot. Just
a thought, since I am by no means an expert potter!

Good luck finding your answer!

Stephanie

Timothy Joko-Veltman on wed 24 jan 07

Tom,

Just guessing here, but from your description, it would seem that the
top glaze is probably higher in things like kaolin and ball clay -
these materials make a wet glaze contract a lot when drying, hence the
cracking. The bottom glaze likely has fewer of these, and therefore
has less of a "grip" on the pot, because these materials also provide
a good mechanical adhesion (viz., sticking because of friction, and
not gluing) - this could account for the flaking.

As for corrections, if you mean changing the glaze composition, unless
it causes problems - bloating, overfiring, pinholing, etc. - do you
really want to? After all, you say the effect is "breath-taking".
Changing the composition of one or both of the glazes will almost
certainly alter the effect completely ...

To avoid touching the flaky glaze, well, I'm sure there are lots of
solutions; the first one that comes to mind for me is to see if it
might be possible to let the piece dry on a kiln shelf. Others will
have other ideas, no doubt.

Regards,

Tim

William & Susan Schran User on thu 25 jan 07

On 1/23/07 9:55 AM, "Tom Sawyer" wrote:

> I have two glazes that I layer; the bottom glaze is very powdery and when
> the top glaze is put on top there is a great deal of cracking and flaking.
> When fired the combination is breath taking. 1. What is the cause? 2. is
> there any easy correction? Thanks for any constructive comments.

First thought would be the bottom glaze does not contain enough clay to
harden the surface when it dries. Might want to try adding a gum binder to
the glaze to harden the surface without altering the firing characteristics.


--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com

Tom Sawyer on thu 25 jan 07

Tim thanks for the explanation. On reflection, I think you are correct. I
posted earlier that I added CMC and this corrected the problem. What I was
really after was what was happening and your explanation seems accurate.

Tom Sawyer

Tom Sawyer on thu 25 jan 07

Exactly what I did before I read your reply and it worked. Thanks

Tom Sawyer

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Snail Scott
Sent: Wednesday, January 24, 2007 11:44 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Glaze Question

At 09:55 AM 1/23/2007 -0500, you wrote:
>I have two glazes that I layer; the bottom glaze is very powdery and when
>the top glaze is put on top there is a great deal of cracking and
flaking...


Try adding CMC or bentonite to the
bottom glaze, to make a harder surface.

-Snail

____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org

You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/

Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.

Tom Sawyer on thu 25 jan 07

Sorry I wasn't more clear. The two glazes used are good by themselves and do
not demonstrate any flaking or cracking before or after firing - BUT - when
placed one on the other they exhibit a lot of cracking and even some flaking
before firing; after the firing the glaze is spectacular and there is no
hint of crazing or flaking. Yesterday I mixed in a bunch of CMC and this
corrected the problem. The reason I didn't include the formulas is that I
don't want to alter either of these glazes as they are quite good by
themselves. I was just wondering what might be occurring. Thanks for the
reply.

Tom Sawyer

Joseph Herbert on sun 7 oct 07

Sandi asks about glazing a bowl made from unknown clay:

It seems that the intention would be to apply glaze to help preserve the
object for its sentimental value and that utility might be secondary. If
that is the case, treating the piece as if it were made of earthenware, low
fire clay, is the safest in terms of not melting the bowl. You could just
select a clear no-lead low fire glaze, coat the piece (entirely if you can
use a stilt to keep it off the shelf) and fire to cone 04 - 06 range. I
don't think there are any actual ceramic materials that you could damage
doing this.

Since you have written to this list and have the last name of a famous
ceramics author, I have assumed you might know what that all the above
means. If the above is just gibberish for you, find a pottery painting
studio in your city and take the piece there. Tell them your story and
insist you don't want to risk damaging the piece. They should be able to
guide you with colors, application, and other questions. You might try to
find the person who seems most knowledgeable about firing. Some of the
people there will be mostly painters, nothing wrong with that, but your
question is a little more in the technical pottery realm.

Joe

Joseph Herbert
Technical Writer
Irving, Texas
214-725-8305 (Cell)

Sally Guger on mon 10 mar 08

Hi all,
I don't know if this problem has made the inside of pots unsafe.
My co-worker over-fired a bisque load- set the electronic controller at 04, which is more like 03 or maybe higher.
The pots will accept glaze- but not all that willingly!
The cone 6 butterscotch glaze did a strange thing- the tan color stayed on the pot- (I use a speckle brownstone from A.R.T.- but the creamy color ran to the bottom of the mug. It has 9% titanium dioxide- if that is what ran- is it still food safe? I think it is- it was fired to cone 6.
(This recipe is a revised by RR one in the clayart archives.)
Thanks. Sally




Live, Give, Love
Beyond All Expectation.
Sally Guger
Lakespur Blue Pottery & Sculpture
Lodi, Wisconsin, USA
http://www.saukpr.k12.wi.us/~gugersa/the_art_teachers.htm


---------------------------------
Never miss a thing. Make Yahoo your homepage.

Lis Allison on mon 4 may 09

On Monday 04 May 2009 20:02, KATHI LESUEUR wrote:
>Years ago when a grocery store was going out of
> business I was able to get large containers that were lined with
> fiberglass and were on heavy duty wheels. They hold about sixty grams
> of glaze. Everything I make can be dipped in these containers.

OK, you don't mean 60 grams, but we get the idea.

I use two of those fibreglass laundry sinks to hold my production glazes.
The only tricky bit is finding a good stopper - just imagine if it came
out...... but Gorilla Glue came to the rescue.

The beauty of the sinks is that they are at a comfortable working height
and I can dip 26" platters.

They're cheap, too.

Lis

--
Elisabeth Allison
Pine Ridge Studio

Lee Love on mon 4 may 09

In Japan they use Muriatic acid to take the bloom off of oribe.
--
--
Lee Love in Minneapolis
http://mingeisota.blogspot.com/
"The secret of life is to have a task, something you devote your
entire life to, something you bring everything to, every minute of the
day for the rest of your life. And the most important thing is, it
must be something you cannot possibly do." - Moore, Henry

KATHI LESUEUR on mon 4 may 09

At a recent show I was chatting with another potter. As often happens
the conversation got around to glazes and glaze applications. He told
me he used muratic acid in his glazes to thicken them and to keep
from having drips on edges when dipped. About one teaspoon to a five
gallon bucket. Before I go out and buy some muratic acid I thought
I'd see if anyone else has used this in their glazes and how well did
it work. Problems it created?

Thanks all,


KATHI LESUEUR
http://www.lesueurclaywork.com

Lee Love on mon 4 may 09

I wonder if concentrated lime juice would be a safe alternative?

--
Lee Love in Minneapolis
http://mingeisota.blogspot.com/
"The secret of life is to have a task, something you devote your
entire life to, something you bring everything to, every minute of the
day for the rest of your life. And the most important thing is, it
must be something you cannot possibly do." - Moore, Henry

John Hesselberth on mon 4 may 09

Hi Kathi,

Muriatic acid is impure hydrochloric acid. It will flocculate glazes
the same as a number of other materials. It will not decompose like
vinegar or other organic acids will but, on the other hand, is a
stronger acid and a bit more dangerous to handle--it can be handled
safely, just be careful. Epsom salts or bentonite would have a
similar effect and are probably more reliable and safer to use.

Regards,

John

On May 4, 2009, at 3:55 PM, KATHI LESUEUR wrote:

> At a recent show I was chatting with another potter. As often happens
> the conversation got around to glazes and glaze applications. He told
> me he used muratic acid in his glazes to thicken them and to keep
> from having drips on edges when dipped. About one teaspoon to a five
> gallon bucket. Before I go out and buy some muratic acid I thought
> I'd see if anyone else has used this in their glazes and how well did
> it work. Problems it created?
>
> Thanks all,
>
>
> KATHI LESUEUR
> http://www.lesueurclaywork.com

John Hesselberth
www.frogpondpottery.com

"Man is a tool-using animal....without tools he is nothing, with tools
he is all" .... Thomas Carlyle

KATHI LESUEUR on mon 4 may 09

Bill,

Thanks for such a thorough answer to my question. I have two glazes
that I fight with all of the time so I'll experiment and see if this
is the solution. Years ago when a grocery store was going out of
business I was able to get large containers that were lined with
fiberglass and were on heavy duty wheels. They hold about sixty grams
of glaze. Everything I make can be dipped in these containers. I am
familiar with using the acid from the days I taught some jewelry and
did acid etching. So, I know the precautions.

KATHI LESUEUR
http://www.lesueurclaywork.com



On May 4, 2009, at 6:02 PM, Bill Merrill wrote:

> Muriatic acid does work. I use it in glazes that I don't want not to
> have runs on the glaze. When the acid is added to the glaze it has a
> pudding like consistency...........

piercepottery@AOL.COM on tue 5 may 09

Hello Liz. Am I misunderstanding you, or do you glue the stopper into
the sink drain hole, sealing it permanently? Lori Pierce, Orange
Park, Florida


-----Original Message-----
From: Lis Allison
To: Clayart@LSV.CERAMICS.ORG
Sent: Mon, 4 May 2009 9:30 pm
Subject: Re: glaze question

On Monday 04 May 2009 20:02, KATHI LESUEUR wrote:
>Years ago when a grocery store was going out of
> business I was able to get large containers that were lined with
> fiberglass and were on heavy duty wheels. They hold about sixty grams
> of glaze. Everything I make can be dipped in these containers.

OK, you don't mean 60 grams, but we get the idea.

I use two of those fibreglass laundry sinks to hold my production
glazes.
The only tricky bit is finding a good stopper - just imagine if it came
out...... but Gorilla Glue came to the rescue.

The beauty of the sinks is that they are at a comfortable working height
and I can dip 26" platters.

They're cheap, too.

Lis

--
Elisabeth Allison
Pine Ridge Studio

Lis Allison on tue 5 may 09

On Tuesday 05 May 2009 10:47, you wrote:
> Hello Liz. Am I misunderstanding you, or do you glue the stopper into
> the sink drain hole, sealing it permanently? Lori Pierce, Orange
> Park, Florida

Yes, I did. The thought of the stopper coming out when I hit it with the
stirring stick gave me the willies so I glued the ABS plastic stopper in
place. Why not? I'll never need to drain the sink and if I do I can bail
it out.

Lis

--
Elisabeth Allison
Pine Ridge Studio

Liisa Reid on tue 5 may 09

I used one of those sinks for several years. To me, one of the big
advantages was that I COULD drain it, instead of having to bail it out. I
kept a 5 gallon bucket underneath, "just in case" I knocked the plug loose.
Liisa

On Tue, May 5, 2009 at 9:41 AM, Lis Allison wrote:

> On Tuesday 05 May 2009 10:47, you wrote:
> > Hello Liz. Am I misunderstanding you, or do you glue the stopper into
> > the sink drain hole, sealing it permanently? Lori Pierce, Orange
> > Park, Florida
>
> Yes, I did. The thought of the stopper coming out when I hit it with the
> stirring stick gave me the willies so I glued the ABS plastic stopper in
> place. Why not? I'll never need to drain the sink and if I do I can bail
> it out.
>
> Lis
>
> --
> Elisabeth Allison
> Pine Ridge Studio
>

Steve Slatin on mon 30 nov 09

Was it not that defender of the right,
Super Chicken, who clucked "Needs More
Tabasco, Fred"?

For ^6 to work (and not run excessively)
you can't have too much melter, and you
must have a balance between glass former
and stiffener.

Boron is interesting, it promotes melting
and also acts as a glass former. If you
add your two glass formers together (boron
and silica) you're close to 80% -- at the=3D20
high end of normal.=3D20

If you do the ratio of glass formers
to stiffeners ((boron plus silica)/alumina)
you get a ratio of 13.2 -- even leaving
the boron out you are at almost 11 to 1.

And if you add the boron to the 'regular'
melters, you've got lots of melters there
(about 30%).

What this adds up to is that you need
more alumina. Drop the silica to 34, raise
the kaolin to 14, and it'll probably be
fairly well behaved and still have the
high-boron characteristics that you like.

If it's still runny, try silica 33 and kaolin
15 -- and then silica 32 and kaolin 16. I
think you'll find a better-behaved outcome
in that range.



Steve Slatin =3D20




--- On Mon, 11/30/09, fran johnson wrote:

> From: fran johnson
> Subject: glaze question
> To: Clayart@LSV.CERAMICS.ORG
> Date: Monday, November 30, 2009, 11:58 AM
> I have a cone 4 gloss=3DA0glaze
> (oxidation)=3DA0that I used years ago that I really liked.
> Really simple, only 3 ingredients. It worked as well at cone
> 5, but at 6 it ran if too thick-not a problem at 4 or 5, or
> "seperated" into translucent and clumpy areas of the color
> at the lower temp. The surface is still smooth and it feels
> no different than if fired at a lower temp.=3DA0 This isn't a
> very good description, but the best I can give. I've also
> described it as looking like curdled milk, if milk had a
> color,seperated into clumps and liquid.
> =3DA0
> Can anyone suggest a way to adjust this glaze to cone 6 ?
> =3DA0
> RB 10 c-6, oxidation=3D20
> =3DA0
> gerstley borate=3DA0=3DA0=3DA0 52
> kaolin=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=
=3DA0=3DA0=3DA0=3DA0=3DA0 12
> silica=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=
=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0 36
> =3DA0
> I know it has a lot of gerstley borate in it, and I am
> aware of all the arguements pro and con. But I like the feel
> of the glaze as well as the look.=3D20
> =3DA0
> Thanks for any help.
> =3DA0
> Fran=3DA0
> =3D0A=3D0A=3D0A

fran johnson on mon 30 nov 09

I have a cone 4 gloss=3DA0glaze (oxidation)=3DA0that I used years ago that =
I re=3D
ally liked. Really simple, only 3 ingredients. It worked as well at cone 5,=
=3D
but at 6 it ran if too thick-not a problem at 4 or 5, or "seperated" into =
=3D
translucent and clumpy areas of the color at the lower temp. The surface is=
=3D
still smooth and it feels no different than if fired at a lower temp.=3DA0=
T=3D
his isn't a very good description, but the best I can give. I've also descr=
=3D
ibed it as looking like curdled milk, if milk had a color,seperated into cl=
=3D
umps and liquid.
=3DA0
Can anyone suggest a way to adjust this glaze to cone 6 ?
=3DA0
RB 10 c-6, oxidation=3D20
=3DA0
gerstley borate=3DA0=3DA0=3DA0 52
kaolin=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA=
0=3DA0=3DA0=3DA0=3DA0 12
silica=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA=
0=3DA0=3DA0=3DA0=3DA0=3DA0 36
=3DA0
I know it has a lot of gerstley borate in it, and I am aware of all the arg=
=3D
uements pro and con. But I like the feel of the glaze as well as the look.=
=3D
=3D20
=3DA0
Thanks for any help.
=3DA0
Fran=3DA0

Anne Elisabeth Maurland on mon 30 nov 09

Hi Fran,

The glaze I've been using is a lot like yours (gerstley borate 50, EPK=3D20=
=3D

15, Silica 35), it was also originally a cone 4 glaze, but I now use it=3D2=
0=3D

at cone 6. It appears I have a glaze fit problem, and I'm trying out=3D20
some other recipes at the moment.

One is Ron Roy's suggestion, which is on a test tile in the kiln right=3D20=
=3D

now:

Gertsley 46
EPK 10
Silica 22
G-200 22

I know very little or nothing about glaze calculation, so I shouldn't=3D20
even be answering, but the problem you describe happened to my glaze a=3D20=
=3D

few years ago. (Normally it looks the same at ^6 as ^4).
It turned out the gerstley borate had become too moist. The basement=3D20
had flooded, and although the bag was up off the floor and didn't=3D20
appear wet, the moisture had ruined the material, which apparently is=3D20
especially susceptible to humidity.
The glaze I made with it looked like what you describe. I had to throw=3D20=
=3D

all the affected GB out.

Elisabeth


On Nov 30, 2009, at 1:58 PM, fran johnson wrote:

> I have a cone 4 gloss=3DA0glaze (oxidation)=3DA0that I used years ago tha=
t =3D
I=3D20
> really liked. Really simple, only 3 ingredients. It worked as well at=3D2=
0=3D

> cone 5, but at 6 it ran if too thick-not a problem at 4 or 5, or=3D20
> "seperated" into translucent and clumpy areas of the color at the=3D20
> lower temp. The surface is still smooth and it feels no different than=3D=
20=3D

> if fired at a lower temp.=3DA0 This isn't a very good description, but =
=3D
the=3D20
> best I can give. I've also described it as looking like curdled milk,=3D2=
0=3D

> if milk had a color,seperated into clumps and liquid.
> =3DA0
> Can anyone suggest a way to adjust this glaze to cone 6 ?
> =3DA0
> RB 10 c-6, oxidation
> =3DA0
> gerstley borate=3DA0=3DA0=3DA0 52
> kaolin=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=
=3DA0=3DA0=3DA0=3DA0=3DA0 12
> silica=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=
=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0 36
> =3DA0
> I know it has a lot of gerstley borate in it, and I am aware of all=3D20
> the arguements pro and con. But I like the feel of the glaze as well=3D20=
=3D

> as the look.
> =3DA0
> Thanks for any help.
> =3DA0
> Fran=3DA0
>

John Britt on mon 30 nov 09

I think that would be :

Milk Gloss cone 6

50 Gerstley Borate
30 Silica
20 Kaolin,

John Britt

Anne Elisabeth Maurland on tue 1 dec 09

The glaze came out looking just like my old glaze (which is good -=3D20
clear and shiny!), and hopefully the fit is better so that I won't have=3D2=
0=3D

the cracking problem anymore. I will be conducting tests when I get=3D20
home from Florida in a week!

Elisabeth
On Dec 1, 2009, at 8:35 AM, fran johnson wrote:

> Elizabeth,
> =3DA0
> Thanks for the help; I'd be interested=3DA0to hear about=3DA0the results =
=3D
of=3D20
> your tests. What clay(s) are you using?
> John Britt also replied with a recipe, very similar to mine. It is one=3D=
20=3D

> I've seen before never used and did not know how close they are. I=3D20
> will be doing some tests today- firing a kiln tomorrow for a First=3D20
> Thursday open house.
> =3DA0
> Fran
>
> --- On Mon, 11/30/09, Anne Elisabeth Maurland=3D20
> wrote:
>>
>> From: Anne Elisabeth Maurland
>> Subject: Re: glaze question
>> To: "fran johnson"
>> Cc: Clayart@LSV.CERAMICS.ORG
>> Date: Monday, November 30, 2009, 3:11 PM
>>
>> Hi Fran,
>>
>> The glaze I've been using is a lot like yours (gerstley borate 50,=3D20
>> EPK 15, Silica 35), it was also originally a cone 4 glaze, but I now=3D2=
0=3D

>> use it at cone 6. It appears I have a glaze fit problem, and I'm=3D20
>> trying out some other recipes at the moment.
>>
>> One is Ron Roy's suggestion, which is on a test tile in the kiln=3D20
>> right now:
>>
>> Gertsley 46
>> EPK 10
>> Silica 22
>> G-200 22
>>
>> I know very little or nothing about glaze calculation, so I shouldn't=3D=
20=3D

>> even be answering, but the problem you describe happened to my glaze=3D2=
0=3D

>> a few years ago. (Normally it looks the same at ^6 as ^4).
>> It turned out the gerstley borate had become too moist. The basement=3D2=
0=3D

>> had flooded, and although the bag was up off the floor and didn't=3D20
>> appear wet, the moisture had ruined the material, which apparently is=3D=
20=3D

>> especially susceptible to humidity.
>> The glaze I made with it looked like what you describe. I had to=3D20
>> throw all the affected GB out.
>>
>> Elisabeth
>>
>>
>> On Nov 30, 2009, at 1:58 PM, fran johnson wrote:
>>
>> > I have a cone 4 gloss=3DA0glaze (oxidation)=3DA0that I used years ago =
=3D
that=3D20
>> I really liked. Really simple, only 3 ingredients. It worked as well=3D2=
0=3D

>> at cone 5, but at 6 it ran if too thick-not a problem at 4 or 5, or=3D20=
=3D

>> "seperated" into translucent and clumpy areas of the color at the=3D20
>> lower temp. The surface is still smooth and it feels no different=3D20
>> than if fired at a lower temp.=3DA0 This isn't a very good description,=
=3D20=3D

>> but the best I can give. I've also described it as looking like=3D20
>> curdled milk, if milk had a color,seperated into clumps and liquid.
>> > =3DA0
>> > Can anyone suggest a way to adjust this glaze to cone 6 ?
>> > =3DA0
>> > RB 10 c-6, oxidation
>> > =3DA0
>> > gerstley borate=3DA0=3DA0=3DA0 52
>> > kaolin=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA=
0=3DA0=3DA0=3DA0=3DA0=3DA0 12
>> > silica=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0=3D=
A0=3DA0=3DA0=3DA0=3DA0=3DA0=3DA0 36
>> > =3DA0
>> > I know it has a lot of gerstley borate in it, and I am aware of all=3D=
20=3D

>> the arguements pro and con. But I like the feel of the glaze as well=3D2=
0=3D

>> as the look.
>> > =3DA0
>> > Thanks for any help.
>> > =3DA0
>> > Fran=3DA0
>> >
>>

Allyson May on sun 21 mar 10

Hey Folks,

Does anyone know if the Crackle Slip recipe on page 62 of John Brit's =3D
High Fire Glazes book is for application to wet, leather, dry, bisque? =3D
I have been trying to contact John but I don't think I have the right =3D
email. Thanks in advance if anyone has the scoop and can help me out.

Peace,
Allyson May
www.stoneycreekpottery.com