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newbie continues w/glaze, slip and stains

updated mon 24 sep 01

 

Dori Grandstrand on tue 18 sep 01


Hello All,
I would like to express my absolute gratitude to everyone who has
responded to my plea for help. As expected, a few of you asked for further
info, such as the glaze recipe that I am using. Primarily, I am using a
recipe which was given to me as "Jodi's Clear", but I've received a response
calling it "Vivian's Clear" -- I guess it depends on the name of the person
who gives it to you. The recipe is as follows:
Silica 20
F.3134 50
EPK 30
If any of you have suggestions on how I can alter/improve this recipe to
fit porcelain better, please let me know -- I'll try everything. In another
test, I added 15% Whiting to this recipe, but it didn't affect the mason
stain colors at all (purples, pinks, etc.) I have also tried Hansen's
Clear/Base glaze, which has 23% Wollastonite. This was a nice clear glaze,
but still crazed and the Wollastonite had no effect on the stains, either.
Other recipes I've tested include Chappell's (for porcelain) and a Ceramic
Monthly Clear/Base. All of these glazes are great as far as being clear and
glossy, but again, were a flop on developing stains, and still crazed. Based
on the responses I'm getting, I can only conclude that perhaps my firing
cycle is too short and cooling too rapidly (Cone 6, 2hr, 15min for low, med,
and high, until fired off, in a rather cool garage).
When all is said and done, I guess I'm still most concerned about getting
color development from the stains in my slip base. Some older postings
(Craig Martell of Oregon -- is he still around?) back in 1997 suggested that
the whiting should be added to the slip base. Another person, (way back in
'97), Robert Speirs, M.D. (Laura), suggested up to 35% of Degussa Red in the
slip base (wow! now that hurts!), and said that they get a range of colors
from "pink to Xmas red". I feel like I must be missing something, so can
anyone respond to these claims? Would Whiting in the SLIP help? 35% of
Degussa Red? Pull my hair out and throw that in?? :)))
Anyone with further ideas, please help!! I am a pretty determined artist,
so I'm not going to let this get in my way -- if folks say they're getting
great colors (red, purple, etc.) in their slips, then I sure do want to know
how!! Again, your posts will be eagerly awaited, and I hope all of this
"discussion" is helping another frustrated potter out there .... --- Dori
Grandstrand, Sultanarts

Ababi Sharon on wed 19 sep 01



Hello Dori


In a saperete letter I send today you might find more help but....


These several names to the glaze you use...                                         


From the Ceramic web:


********************************************

ClayArt Glaze Database Search Results


 


Displaying records 170 through 1 of 1 records found. (1 records
displayed).


Previous page of records.


Glaze Name: Clear (Huddleston)
cone: 5 - 6
color: transparent clear
surface:glossy, shiny
firing:Untested
date: 12/6/96
recipe:
  50.00  Ferro Frit 3134
 30.00  EPK
 20.00  Silica
 100.00 % Totals:


comments:
From the ClayArt Glaze Recipe Database at SDSU.
If you test this glaze and find it useful
please consider resubmitting it to the GlazeBase database.


estimated thermal expansion: 70.79x10-7/C



Unity Formula for Clear (Huddleston):
0.004 K2O  0.419 Al2O3 3.596 SiO2
0.313 Na2O 0.626 B2O3  0.004 TiO2
0.679 CaO  0.004 Fe2O3 8.6:1 Si:Al Ratio
0.004 MgO


Percentage Analysis for Clear (Huddleston):
    59.81 % SiO2
    11.83 % Al2O3
    12.04 % B2O3
     0.11 % K2O
     5.37 % Na2O
    10.54 % CaO
     0.04 % MgO
     0.18 % Fe2O3
     0.09 % TiO2


Possible Health Hazards: Silica: free silica-wear a NIOSH approved dust
mask when handling dry material
It didn't craze but the colors were not quite as bright as others but
it is a nice glaze and subing Ferro frit 3124, I found a nice clear
matt. I hope these help. They're all I could find. Joyce Basking in the
sun in the Mojave joyce lee, jim lee <meunier@ridgecrest.ca.us>


**********************************************************


Where I learned, my teacher used to say, take a glaze, give it a name
and develop it.
Beside being not fair to the developer it makes you not connecting the origin of the glaze or the developed glaze to a source.
 I am really regret on the first Raku glaze test I made  from CM
calling the glazes A B and C.  The result is making these test again and
against you do not remember if you done it before.
Was glaze a/1 Beverly that I liked or Hills that did not mature.
I feel honored to use your glaze and even in the and the glaze is
totally different I try to write (sometimes forget) based on....
Ababi Sharon


Kibbutz Shoval- Israel



officially Glaze addict



ababisharon@hotmail.com



http://members4.clubphoto.com/ababi306910/



http://www.milkywayceramics.com/cgallery/asharon.htm



http://www.israelceramics.org/


 






>From: Dori Grandstrand
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Newbie continues w/Glaze, Slip and Stains
>Date: Tue, 18 Sep 2001 21:08:04 EDT
>
>Hello All,
> I would like to express my absolute gratitude to everyone who has
>responded to my plea for help. As expected, a few of you asked for further
>info, such as the glaze recipe that I am using. Primarily, I am using a
>recipe which was given to me as "Jodi's Clear", but I've received a response
>calling it "Vivian's Clear" -- I guess it depends on the name of the person
>who gives it to you. The recipe is as follows:
>Silica 20
>F.3134 50
>EPK 30
> If any of you have suggestions on how I can alter/improve this recipe to
>fit porcelain better, please let me know -- I'll try everything. In another
>test, I added 15% Whiting to this recipe, but it didn't affect the mason
>stain colors at all (purples, pinks, etc.) I have also tried Hansen's
>Clear/Base glaze, which has 23% Wollastonite. This was a nice clear glaze,
>but still crazed and the Wollastonite had no effect on the stains, either.
>Other recipes I've tested include Chappell's (for porcelain) and a Ceramic
>Monthly Clear/Base. All of these glazes are great as far as being clear and
>glossy, but again, were a flop on developing stains, and still crazed. Based
>on the responses I'm getting, I can only conclude that perhaps my firing
>cycle is too short and cooling too rapidly (Cone 6, 2hr, 15min for low, med,
>and high, until fired off, in a rather cool garage).
> When all is said and done, I guess I'm still most concerned about getting
>color development from the stains in my slip base. Some older postings
>(Craig Martell of Oregon -- is he still around?) back in 1997 suggested that
>the whiting should be added to the slip base. Another person, (way back in
>'97), Robert Speirs, M.D. (Laura), suggested up to 35% of Degussa Red in the
>slip base (wow! now that hurts!), and said that they get a range of colors
>from "pink to Xmas red". I feel like I must be missing something, so can
>anyone respond to these claims? Would Whiting in the SLIP help? 35% of
>Degussa Red? Pull my hair out and throw that in?? :)))
> Anyone with further ideas, please help!! I am a pretty determined artist,
>so I'm not going to let this get in my way -- if folks say they're getting
>great colors (red, purple, etc.) in their slips, then I sure do want to know
>how!! Again, your posts will be eagerly awaited, and I hope all of this
>"discussion" is helping another frustrated potter out there .... --- Dori
>Grandstrand, Sultanarts
>
>______________________________________________________________________________
>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.


Get your FREE download of MSN Explorer at http://explorer.msn.com


John Hesselberth on wed 19 sep 01


on 9/18/01 9:08 PM, Dori Grandstrand at Sultanarts@AOL.COM wrote:

> Hello All,
> I would like to express my absolute gratitude to everyone who has
> responded to my plea for help. As expected, a few of you asked for further
> info, such as the glaze recipe that I am using. Primarily, I am using a
> recipe which was given to me as "Jodi's Clear", but I've received a response
> calling it "Vivian's Clear" -- I guess it depends on the name of the person
> who gives it to you. The recipe is as follows:
> Silica 20
> F.3134 50
> EPK 30
> If any of you have suggestions on how I can alter/improve this recipe to
> fit porcelain better, please let me know -- I'll try everything.

Hi Dori,

I'm going to focus on the glaze issue; others know way more about slip than
I do. Jackie Brien gave some important information in a message a couple
days ago when she gave the RBG recipe that she said didn't craze on your
clay. The calculated expansion (HyperGlaze) of her RGB recipe is 65.1 x
10exp-7. The calculated expansion for your Vivian's/Jodi's clear is 70.9.
So we need to try to get you to an expansion of about 65 without using
Gerstley Borate--I don't like it for any glaze given its questionable
availability and its variability.

The simplest way to get your expansion down to 65 or so is to add talc.
This adds magnesium to the mix which is a low expansion material. In order
to keep the numbers simple and to also get some sodium and potassium out of
the mix I removed some frit.

The recipe I would suggest trying first is

Glaze name: Vivians/Jodis Clear II
Cone: 6
Color: Transparent Clear
Testing: Untested
Surface texture: Shiny or Glossy

Recipe: Percent
Frit 3134 40.00
Talc 10.00
EPK 30.00
Silica 20.00
Totals: 100.00 %

Comments:
Add talc and reduce 3134 vs. original to bring expansion down

Possible Health Hazards:
Talc: wear a NIOSH approved dust mask when handling dry material

Silica: free silica-wear a NIOSH approved dust mask when handling dry
material


Unity Formula for Vivians Clear II:
0.003 K2O 0.363 Al2O3 3.185 SiO2
0.221 Na2O 0.439 B2O3 0.003 TiO2
0.525 CaO 0.003 Fe2O3 8.8:1 Si:Al Ratio
0.251 MgO

Calculated expansion: 65.8 x 10exp-7

Versus the original, this recipe has less sodium and calcium and more
magnesium. It also has less alumina, boron and silica, but they are still in
a range that should give a stable glaze and good melting at cone 6. The
ratio of Si/Al is 8.8 vs. the original of 8.6 so the surface should be about
the same.

If you try this one I would also do a test sample that is half way
in-between. You can do that by line blending or just by mixing a test
sample that is 45:5:30:20 -- whichever is simpler for you. The reason I
suggest a half way test is that magnesia at 0.25 may not give a real clear
glaze--it may be a little cloudy.

It is a little hard to predict how the magnesium in the glaze will affect
your slip colors--particularly since you are using stains which seem to be
affected less by glaze composition than are raw colorants. Magnesium,
though, is known to make cobalt go to mauve or purple rather than blue, so
this could be in the right direction for some of the colors you want.

If you do try this, please let us know how it comes out. If it doesn't work
there are other approaches that could be tried--I have just suggested what I
thought might be simplest first.

Regards,

John


Web site: http://www.frogpondpottery.com Email: john@frogpondpottery.com

"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.

Wade Blocker on wed 19 sep 01


Dori,
Your problem sounds very much like the one I had been having with glazes
crazing. I finally changed my clay and no more crazing.The crazing by
itself would not have overly concerned me, but the fact that I had actual
glaze cracks made the work worthless. The clay that I had been using was
one with a wide temperature range of cone 5 to 9. That was the problem. I
am now using a clay which fires from cone 5 to 6, no more crazing or
cracking. Mia in sunny ABQ

Jackie Brien on thu 20 sep 01


Dori
I am firing Cone 6 porcelain and stoneware usually as follows- low-anywhere
from 3-8 hours, medium about 3 hours and then on High- at that point my kiln
usually takes about another 4-5 hours to reach ^5-6. I also soak for about
the last hour or so-slowing down the firing. Altogether most firings take
about 10-15 hours. I feel that this may be too slow- but the glazes develope
nicely.
On the other hand I made a mistake last week and turned the kiln right on to
high without realizing it. when I came home to turn it up , it took me a few
minutes to realize that it had turned itself off and was a dull cherry red
inside the kiln. I figure it had taken about 5-7 hours to reach
temperature.(It was only 1/2 full ) The glazes were ok but a bit glassy and
not as nice as usual. And I was very relieved.
Jackie

Martin Howard on thu 20 sep 01


It gladdened my heart to see that Abibi quoted both recipe AND the unity
formula of Clear (Huddleston) cone: 5 - 6 for our Newbie.

Even after our many discussions about the need for the unity formula, so
many postings fail to include it.

If you use different sources for your Raw Materials than I or other readers,
your recipe is of no use to us. But the unity formula can enable us, via the
computer program such as David Hewitt's Glaze Book Excel program, get an
almost exact match for testing.

This is a major reason why so many are disappointed when trying out other's
glaze recipes.

Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England

martin@webbscottage.co.uk
http://www.webbscottage.co.uk

Wade Blocker on fri 21 sep 01


Jackie,
You are taking overly long to fire. This is a schedule I can recommend :
for bisque firing, 3 hours on low, 3 hours on medium, then 3 hours on high,
depending how many switches you have on your kiln. In one more hour you
should reach cone 06. No soak is necessary for a bisque firing. Just
keep your doors and windows closed in Winter when you turn your kiln off,
to prevent rapid cooling.I do not empty the kiln until 48 hours.later. By
that time not only the ware, but the kiln itself is cold.
For a glaze firing do the same, except halve the time eg 1 1/2 hours on
low, 1 1/2 hours on medium, 1 1/2 hours on high until it is fully switched
on. Then depending on your kiln load and amount of shelves, you should
reach cone 5-6 in about three to four hours.Always have a set of three
Orton cones which you can see through a peep hole, to verify the
temperature. Soak for 1 hour is all that is required. See above paragraph
before unloading the kiln Hope this helps. Mia in ABQ

Earl Brunner on sat 22 sep 01


Mia, I wouldn't tell anyone that no soaking is necessary on a bisque
fire, I don't know how thick their work is, how wet it is, or how hot
their kiln fires on low. If you get above the boiling point of water
and there is still moisture in the clay you will blow the stuff up,
sometimes violently.

You can certainly fire the rest of the cycle as you recommend, but I
would be a bit more cautious at the beginning, I would have the lid
partly open for an hour or so, if there are more than one switch, I
would turn them on incrementally, beginning with the bottom, one on low
wait a half hour, the next, wait a half hour, etc. I would five it
about an hour with all on low with the lid still open, then another hour
with the lid closed. Once it is turned off, why are you waiting 48
hours? On a bisque you could pull the top plug right after turnning the
turning and probably unload 12 hours later.

Wade Blocker wrote:

> Jackie,
> You are taking overly long to fire. This is a schedule I can recommend :
> for bisque firing, 3 hours on low, 3 hours on medium, then 3 hours on high,
> depending how many switches you have on your kiln. In one more hour you
> should reach cone 06. No soak is necessary for a bisque firing.
>

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

Joan & Tom Woodward on sat 22 sep 01


Mia,

Either you have the patience of a saint, or there was a typo when you said
you don't empty your kiln for 48 hours after it's off. Could you translate
your "low" Medium" and "high" to temperatures? I have a Skutt 1027 with a
controller and can ramp up (and down) at specified temperature gains per
hour until I reach whatever temperatures I designate. I'm still
experimenting myself with different firing profiles. Just did a medium
glaze firing (C 5) with slow cool down that took 15 hours and came out
fine. . . . Joan on a beautiful morning in Grand Junction.
----- Original Message -----
From: Wade Blocker
To:
Sent: Friday, September 21, 2001 9:32 PM
Subject: Re: Newbie continues w/Glaze, Slip and Stains


> Jackie,
> You are taking overly long to fire. This is a schedule I can recommend
:
> for bisque firing, 3 hours on low, 3 hours on medium, then 3 hours on
high,
> depending how many switches you have on your kiln. In one more hour you
> should reach cone 06. No soak is necessary for a bisque firing. Just
> keep your doors and windows closed in Winter when you turn your kiln off,
> to prevent rapid cooling.I do not empty the kiln until 48 hours.later. By
> that time not only the ware, but the kiln itself is cold.
> For a glaze firing do the same, except halve the time eg 1 1/2 hours on
> low, 1 1/2 hours on medium, 1 1/2 hours on high until it is fully switched
> on. Then depending on your kiln load and amount of shelves, you should
> reach cone 5-6 in about three to four hours.Always have a set of three
> Orton cones which you can see through a peep hole, to verify the
> temperature. Soak for 1 hour is all that is required. See above paragraph
> before unloading the kiln Hope this helps. Mia in ABQ
>
>
____________________________________________________________________________
__
> 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.
>

Earl Brunner on sat 22 sep 01


I'm not Mia, but I do fire the art center Skutt 1027's using the
controller. Because some of the student work can be over an inch thick
in places, I use the following for a bisque, using the ramp settings.

50 degrees and hour to 190 degrees, hold for 5 hours, 250 an hour to
900, hold 15 minutes and then 500 an hour to 1750, hold 15 minutes, then
shut down. I haven't blown anything up since I went to this program.

I do shorten the first 5 hours at 190 if I know that things are not too
thick and are thoroughly dry.

In my own studio, with my own pots I would shorten that cycle considerably.

Joan & Tom Woodward wrote:

> Mia,
>
> Either you have the patience of a saint, or there was a typo when you said
> you don't empty your kiln for 48 hours after it's off. Could you translate
> your "low" Medium" and "high" to temperatures? I have a Skutt 1027 with a
> controller and can ramp up (and down) at specified temperature gains per
> hour until I reach whatever temperatures I designate. I'm still
> experimenting myself with different firing profiles. Just did a medium
> glaze firing (C 5) with slow cool down that took 15 hours and came out
> fine. . . . Joan on a beautiful morning in Grand Junction.
> ----- Original Message -----
> From: Wade Blocker
> To:
> Sent: Friday, September 21, 2001 9:32 PM
> Subject: Re: Newbie continues w/Glaze, Slip and Stains
>
>
>
>> Jackie,
>> You are taking overly long to fire. This is a schedule I can recommend
>
> :
>
>> for bisque firing, 3 hours on low, 3 hours on medium, then 3 hours on
>
> high,
>
>> depending how many switches you have on your kiln. In one more hour you
>> should reach cone 06. No soak is necessary for a bisque firing. Just
>> keep your doors and windows closed in Winter when you turn your kiln off,
>> to prevent rapid cooling.I do not empty the kiln until 48 hours.later. By
>> that time not only the ware, but the kiln itself is cold.
>> For a glaze firing do the same, except halve the time eg 1 1/2 hours on
>> low, 1 1/2 hours on medium, 1 1/2 hours on high until it is fully switched
>> on. Then depending on your kiln load and amount of shelves, you should
>> reach cone 5-6 in about three to four hours.Always have a set of three
>> Orton cones which you can see through a peep hole, to verify the
>> temperature. Soak for 1 hour is all that is required. See above paragraph
>> before unloading the kiln Hope this helps. Mia in ABQ
>>
>>
>
> ____________________________________________________________________________
> __
>
>> 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.
>
>
> ______________________________________________________________________________
> 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.


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

Wade Blocker on sat 22 sep 01


Joan, I have a Skutt 1027 -240. It is a cone 10 kiln and has thicker kiln
brick and therefore takes longer to cool down. It is 18 years old and apart
from having the kiln rewired several times, the brick is like new. I
attribute this to not subjecting the kiln to thermal stresses by opening it
too soon. I simply take a day off from potting the day after a firing, so
that I am not tempted to peek into the kiln. The following morning the
kiln might still be lukewarm, but no problem to unpack. I used to fire
cone 9 to 10, then about 10 years ago made the switch to cone 6. Fewer kiln
repairs,i.e. rewiring since then.The first thing I did to my kiln was to
take out the kiln sitter it came with. I am used to firing with cones. I
cannot translate what the temperature is at the various points of my
flipping a switch. By the time all are on high, in a glaze firing the kiln
is barely red. You might see the previous post I sent to Clayart today. If
you have problems still, contact me off line. Mia in sunny ABQ

Wade Blocker on sat 22 sep 01


Earl, You are absolutely right. I forgot to mention that I have the kiln
lid propped during the first three hours of a bisque firing, half that for
glaze. Assumed that this was understood.Got all my information re firing an
electric and gas kiln from manuals and books. Mia in ABQ

Earl Brunner on sat 22 sep 01


hehe,
Some times what we write and what we think we write (what others end up
reading, without the benefit of our thought processes) isn't the same!
Happens to me all the time. The ones I REALLY hate are the goofy
mistakes that my spell checker doesn't catch.

Wade Blocker wrote:

> Earl, You are absolutely right. I forgot to mention that I have the kiln
> lid propped during the first three hours of a bisque firing, half that for
> glaze. Assumed that this was understood.Got all my information re firing an
> electric and gas kiln from manuals and books. Mia in ABQ
>


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

Ron Roy on sun 23 sep 01


This may be completely unnecessary - but - the degrees are in Fahrenheit
in case anyone is wondering.

And I do believe a short soak for bisque is helpful for a number of reasons.

RR

>I'm not Mia, but I do fire the art center Skutt 1027's using the
>controller. Because some of the student work can be over an inch thick
>in places, I use the following for a bisque, using the ramp settings.
>
>50 degrees and hour to 190 degrees, hold for 5 hours, 250 an hour to
>900, hold 15 minutes and then 500 an hour to 1750, hold 15 minutes, then
>shut down. I haven't blown anything up since I went to this program.
>
>I do shorten the first 5 hours at 190 if I know that things are not too
>thick and are thoroughly dry.
>
>In my own studio, with my own pots I would shorten that cycle considerably.

Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513