Dave Kuilema on thu 21 mar 96
Is there any way to make this glaze more fluid? It is too dry when I add 6%
of mason stain titanium yellow. The glaze works fine with other oxides at
cone 6 or 7
Strontium Matt Lith. carb 4 Strontium carb 28 Neph Sy 60 Ball Clay
9 Bentonite 1 Flint 9. Hope there is some advice out there I had hoped
to make it to nceca, but bad weather prevented this, thanks
Bill Buckner on fri 22 mar 96
Dave:
Titanium is refractory and causing your glaze to go dry. You will have to
compensate by increasing the flux to balance the fluidity. Try testing
the glaze (with the titanium stain added), with increasing incriments
(~5%) of the neph. sye. or smaller incriments (~1-2%) of the strontium.
You could also try decreasing the the refractory balance by testing
decreasing incriments of the clay (try it with 6 parts, 3 parts, and 0
parts ball clay). One other possibility is to add a bit of a lower
melting flux, like gerstley borate (although this might change the
character of your glaze a somewhat). Try these and let us know how it
works out.
-Bill
Bill Buckner e-mail: bbuckner@gsu.edu
Georgia State University http://www.gsu.edu/~couwbb
On Thu, 21 Mar 1996, Dave Kuilema wrote:
> ----------------------------Original message----------------------------
> Is there any way to make this glaze more fluid? It is too dry when I add 6%
> of mason stain titanium yellow. The glaze works fine with other oxides at
> cone 6 or 7
> Strontium Matt Lith. carb 4 Strontium carb 28 Neph Sy 60 Ball Clay
> 9 Bentonite 1 Flint 9. Hope there is some advice out there I had hoped
> to make it to nceca, but bad weather prevented this, thanks
>
PlatypusD@aol.com on sat 23 mar 96
The flux in your glaze is neph sy - try increasing it in 5% increments until
you get he melt you want
Let us know how it works out
kk
peter pinnell on mon 25 mar 96
As a quick-and-dirty solution for slightly underfired cone 6 glazes, add
5 to 10% gerstley borate. With all the lithium carb.in this, you will
also want to add a strong flocculant. Try adding 1/4 to 1/2% epsom salts,
or muriatic acid (usually 1-2 tablespoons per 10,000 grams dry weight of
glaze, but a glaze like this may require more in the neighborhood of 1/4
cup per 10,00 grams).
Pete Pinnell
On Thu, 21 Mar 1996, Dave Kuilema wrote:
> ----------------------------Original message----------------------------
> Is there any way to make this glaze more fluid? It is too dry when I add 6%
> of mason stain titanium yellow. The glaze works fine with other oxides at
> cone 6 or 7
> Strontium Matt Lith. carb 4 Strontium carb 28 Neph Sy 60 Ball Clay
> 9 Bentonite 1 Flint 9. Hope there is some advice out there I had hoped
> to make it to nceca, but bad weather prevented this, thanks
>
Dave Kuilema on mon 1 apr 96
to ppinnell (and othes who offered suggestions),
Thanks for the reply to my cry for help re the strontium glaze. It was one
I had gotten from a CM supplement and I realize now it was one of yours.
My usual first response to a dull glaze is to add some G. Borate: the lazy
potter's way out of glaze difficulties, I thought there must be some magic
alternative I don't know about. I did get some other suggestions from
various people through clayart. Some worked, some didn't. Decreasing the
clay and adding 1% of lithium didn't make too big a change. I will try the
5% G.B. in the new firing and let you know what happened. In the meantime
the customer for whom I jumped through all these hoops decided to go with
one of my earlier tests for yellow. The small Aim test kiln which I have
used on occasion for quick tests always turns out a completely different
product than my 10 Cu. Ft. electric. Amazingly different! even when I try
to increase temperature very slowly and mimic the usual firing schedule.
Anyway, the final test on the real tiles for the actual job(gulp) is in the
kiln cooling right now, and I will have pottery nightmares tonight
wondering if it will look OK. I have just begun a whole new career in
architectural ceramics. Basically this means having to work with decorators
and customers for whom matching the countertop is of more than passing
importance; it's a whole new world out there. I resolve again to always
throw a few glaze tests in every firing. It's the least fun part of the
process for me but obviously a necessary evil.
I am very new to clayart and pleased by the response to my glaze
question! Thanks again,
Mary Kuilema, in Michigan, where it still looks like winter.
Christine Davis on thu 13 feb 97
Please forgive me if this is a stupid question, but I recently had a problem
with a "new" glaze and wonder if the problem was me, or the glaze.
I fire in an electric kiln to cone 04-05. This firing schedule was what the
glaze container said to do (I used a commerically prepared glaze from
Piedmont Pottery).
I was firing about 10 pots made my sweet ladies in our local Senior
Center. Every single one of them was covered with small holes, like
popped bubbles, or pinpricks. I would have thought that there was dust
in my kiln, but there were not holes on the inside or tops of the pots, just
on the sides, which didn't make sense if dust had fallen down. Also, all
shelves had the equal problem. I did notice an excessive amount of smoke/
fumes when the firing started, and wonder if that had something to do with
the problem. So, do you think it was something I did, or was the problem
inherent in the glaze? I'd hate to think I ruined all these ladies' pots,
but it would be helpful if I knew if I had done something wrong. Thanks in
advance.
Vince Pitelka on fri 14 feb 97
>I was firing about 10 pots made by sweet ladies in our local Senior
>Center. Every single one of them was covered with small holes, like
>popped bubbles, or pinpricks.
Christine -
Without knowing more about the glaze and the firing schedule, I would guess
that the problem was due to abrupt cooling, which often happens with a
sparsely loaded kiln. Basically, the glaze has barely begun to flow and
"heal" (bubbles are a natural consequence of outgassing - volatiles escaping
from the clay and the glaze melt), and then the kiln shuts off. If the kiln
is sparsely filled, there is nothing to hold the heat, and the glaze
solidifies before it has a chance to heal. On occasions where I have been
forced to fire a sparsely filled electric kiln, I simply place a few hard
brick on each level of the kiln. The hard brick absorb an enormous amount
of energy, and once the elements turn off, they re-radiate this energy, in
effect soaking the kiln near maximum temperature. I suggest you refire the
work in this fashion, but remember that already-glaze-fired work must be
fired slower than bisqued work, because it is less thermal shock resistant,
even if it is only the glaze which is vitrified (as in a porous low-fire body).
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts
1560 Craft Center Drive, Smithville TN 37166
BRENT ANFINSON on sun 16 feb 97
The problem could also be your kiln.There could be a cold spot at
the bottom .In other words,your coils at the bottom could be in need
of some repair.You could also raise your wares up by putting a shelf
in a higher position then you normally do.It could also be your kiln
sitter.Does your cone make a U or a V shape,that could give you some
clues.Good luck M.
Doug Gray on sun 16 feb 97
Christine
I don't normally fire low fire commercial glazes, but it sounds like you
didn't get the temperatire hot enough for the glaze to fully mature.
Try refiring the pieces to one cone higher and see if that solves your
problem. Glazes actually start to bubble and boil before they smooth
over and melt. Sounds like your kiln just began cooling too quickly to
allow the glaze to heal/smooth over those bubbles.
Doug Gray
Alpine, TX
Emily P. Henderson on mon 17 feb 97
At 11:21 AM 2/16/97 EST, you wrote:
>----------------------------Original message----------------------------
>The problem could also be your kiln.There could be a cold spot at
>the bottom .In other words,your coils at the bottom could be in need
>of some repair.You could also raise your wares up by putting a shelf
>in a higher position then you normally do.It could also be your kiln
>sitter.Does your cone make a U or a V shape,that could give you some
>clues.Good luck M.
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Hi There...... I didn't know about the "u" or "v" shape. Can you fill me in?
TIA Emily in Astoria where I'm not squinting from the flash of sunlight anymore
Michele Jurist on sun 20 dec 98
Hi:
Have you tried refiring a cone or 2 hotter? It works for me sometimes to
correct the bubbles. Also, you could try soaking the kiln for an hour at the
end of your firing to see if that works.
Michele in Seattle
Bill Williams on sat 9 jan 99
Even after working in ceramics for 20 years, I don't feel qualified to be in=
the
same conversation with most of you, but I'm going to jump in anyway. I =
started
working on the wheel about 3 years ago, after spending those years before =
making
and selling porcelain dolls. I have been making my own glazes for the past =
year,
and have several that I am very happy with, but now I have a problem. I =
have
recently changed from using a white cone 6 stoneware clay to a black =
stoneware
cone 6 clay. (When fired to cone 6 the stoneware is a soft medium brown =
color).
I am much happier with the black clay, and don't want to change back, but =
feel
like I have wasted a lot of time experimenting with glazes that no longer =
work.
The base glaze I use is: Lithium Carb. 8.9, Custer Feldspar 24.8, Whiting =
13.4,
Kaolin 11.5, Silica 32.2, Ultrox 9.2, CMC 1t. I have adjusted some of the =
blues
to my satisfaction but I'm still feeling frustrated. For instance, the
beautiful turquoise I had with the white clay (added 4=25copper and 8=25 =
Titanium)
comes out dark gray with a spot of turquoise here and there, when I put it =
on
the darker clay. I didn't think an opaque glaze would be affected as much =
by
the color of the clay, as a transparent glaze would be. I knew I would have =
some
adjusting to do, but had no idea it would be so drastic. (don't know the
composition of the clay) Your suggestions will be most welcome. Thanks.
Connie
(billwms=40fn.net)
Alex Wilson on mon 11 jan 99
Hello Connie, to keep the glazes you already have, try covering your new clay
with slip. Something simple = 40 China Clay/
60 Ball Clay. This should give you a white base to glaze over and give you
back your colours.
I have some slightly more complicated recipes, if you need them.
Good Luck,
Alex
Bill Williams on tue 12 jan 99
Alex: Thanks for the help. I got similar advice from Peter Atwood, but I
wonder if that would be defeating my purpose, so to speak. Not only is the
black clay a dream to throw, I like the way it looks when the pieces are
only partially glazed on the outside. I didn't like the partially glazed
pieces I did using the white clay. I did get one other response to my
glaze question. It was quite an elaborate process to get to all the
information. What it boiled down to was that we need to get away from
"textbook recipes" and take control of the glaze base, etc.....However, even
tho that sounds good and it would be wonderful to have all that knowledge
(you probably do), I simply don't. I have gone a long way in 3 years, and I
have learned a lot about making my glazes, and what works and what doesn't,
but the "formula and analysis" mumbo jumbo, is still Greek to me. If I knew
all that, I wouldn't have this problem. I am just a small town grandmother
who loves pottery and I sell enough to about break even. I do experiment
with the glazes, but I have to have a base glaze to start with. If you have
glaze recipes that you are willing to share, I would be most grateful.
Thanks,
Connie
(billwms@fn.net)
From: Alex Wilson
To: CLAYART@LSV.UKY.EDU
Date: Monday, January 11, 1999 1:17 PM
Subject: Re: Glaze problems
>----------------------------Original message----------------------------
>Hello Connie, to keep the glazes you already have, try covering your new
clay
>with slip. Something simple = 40 China Clay/
>60 Ball Clay. This should give you a white base to glaze over and give you
>back your colours.
>I have some slightly more complicated recipes, if you need them.
>Good Luck,
>Alex
>
hal mc whinnie on wed 13 jan 99
i am accepting new members in the glaze of the week, please send me an
email re3quest
also i have an online glaze course, a new session will begin in april
send a request to be added to the class list which is now being formed.
my intention is to offer fthe on line glaze course three times a year as
a part of the institutte for arts education digitial whioch is in the
process of developing several course for an online curriculium that shall
be offered on the quater system basis
all these are free
GLAZE OF THE WEEK
DEC 24 1998
LAST GLAZE FOR 1998 1100 TO 1140
455 ARTIGAS OPAQUE BLUE
Lead 40
Silica 35
Borax 10
Epk 7
Whiting 18
Cobalt carb 2
Frit and mix with 8% Epk
Artigas has a system for the use of lead, which was desirable for so many
of his glaze that would be used on out door murals, sculptures, and
tiles. He made his own glaze frit and them combined them in a variety of
ways.
Melting power high
Melter amount low
Sio2 high
Al2o3 very low
Melters normal
According to zakin the recipe you have formulated does not match the
perimeters of a glaze, engobe or slip. This is because it is either too
low or too high in silica, alumna or flux
The recipe is very low in alumna and it will flow excessively, one should
add at least 10 % clay
FIRST GLAZE FOR 1999
467 artigs turoqouise green glaze
Feldspar 20
Silica 15
Epk 16
Potash carb 9
Whiting 12
Lead 25
Borax 20
Copper carb 5
Melting power high
melter amount normal
All elements normal
This is the quintessential balanced glaze type; it encourages reliable
durable, non-flowing glazes with appealing surfaces.
Note:
This is the last glaze of week for 1998. I will begin again after the New
Year celebration.
I am trying a new format in which I prepare a file and then insert as
text into email. I will use the same approach for the ceramic glaze
course which some of you will be getting after Jan 1 1999.
I will begin to ask for separate registrations for the second round of
the glaze course, which shall begin in April 1999.
These activities are now sponsored by The Institute for Arts Education,
digital.
Waldo, Carol on thu 29 jul 99
Hello Clayarters,
I am trying to develop a clear cone 6 glaze that works well with my clay
body (Plainsman P300 mid-fire Porcelain) and slip decoration.
I tried Tony Hansens base:
20 Silica
20 EPK Kaolin
20 Wollastonite
20 Frit 3134
20 Custer Feldspar
On my clay this glaze crazes.
Test 2: Based on some recent postings, I tried addition of 5% more silica.
On this test I used some clay that had slip decoration on it so that I was
able to see that it not only still crazed but there appears to be tiny
bubbles suspended throughout - could that be boron clouding? In addition, on
one test piece I had used a slip containing 10% Mason stain - deep crimson
and the colour was dull beige instead of Deep crimson. The other colours
tested appeared to be okay.
Please HELP!!
I see this as two distinct problems. 1) To obtain a clear, well fitting
glaze that works on most coloured slips and 2) If possible make that glaze
work with the crimson as well.
Further reading indicates that maybe I should have tried increasing the
Frit. In what amounts? And would that compound the problem with the crimson
stain?
I would sure appreciate any help you can give me before I rip out all of my
hair!
Carol
in sunny Victoria
cwaldo@bcbc.bc.ca
Sharon on fri 30 jul 99
------------------
Carol my suggestion would be to talk to Tony. He will very likely be able =
to
tell you how to get a proper fit between the clay and the glaze. Tony works=
at
Plainsman and will be very familiar with the P300 that you are currently =
using.
Good luck.
Sharon
Medicine Hat, AB
Autumn Downey on sun 1 aug 99
Hello Carol,
Am posting a glaze that we have been using. It's always been a nice
"clear" clear that did well with slips. However it did craze on Plainsman
porcelains and occasionally on the 370. I revised it abit and got further
help from Ron Roy, so it now bears his name - whether he wants it to or not.
We've only tried it on 370 and it seems fine. If you try it, please let me
know how it does on porcelain.
Ron Roy Clear
=============
F-4 FELDSPAR........ 31.00 31.00%
SILICA.............. 21.00 21.00%
FRIT 3134........... 5.00 5.00%
GERSTLEY BORATE..... 10.00 10.00%
EPK KAOLIN.......... 17.00 17.00%
WHITING............. 13.00 13.00%
TALC................ 3.00 3.00%
========
100.00
CaO 0.54* 12.11%
MgO 0.10* 1.64%
K2O 0.05* 1.90%
Na2O 0.14* 3.48%
TiO2 0.00 0.07%
Al2O3 0.35 14.23%
B2O3 0.16* 4.42%
P2O5 0.00 0.05%
SiO2 2.60 61.90%
Fe2O3 0.00 0.21%
Cost/kg 1.55
Si:Al 7.38
SiB:Al 7.84
Expan 7.05
Autumn Downey (in cool grey Yellowknife. Not much summer this year.)
Antoinette Badenhorst on mon 2 aug 99
Carol what will happen if you add some whiting and decrease some of
your other flux(fritt). Whiting will decrease crazing. On a low temp.it
may bubble,but I guess ^6 is high enough. Good luck.
Antoinette
--- "Waldo, Carol" wrote:
> ----------------------------Original
> message----------------------------
> Hello Clayarters,
>
> I am trying to develop a clear cone 6 glaze that
> works well with my clay
> body (Plainsman P300 mid-fire Porcelain) and slip
> decoration.
>
> I tried Tony Hansens base:
> 20 Silica
> 20 EPK Kaolin
> 20 Wollastonite
> 20 Frit 3134
> 20 Custer Feldspar
>
> On my clay this glaze crazes.
>
> Test 2: Based on some recent postings, I tried
> addition of 5% more silica.
> On this test I used some clay that had slip
> decoration on it so that I was
> able to see that it not only still crazed but there
> appears to be tiny
> bubbles suspended throughout - could that be boron
> clouding? In addition, on
> one test piece I had used a slip containing 10%
> Mason stain - deep crimson
> and the colour was dull beige instead of Deep
> crimson. The other colours
> tested appeared to be okay.
>
> Please HELP!!
>
> I see this as two distinct problems. 1) To obtain a
> clear, well fitting
> glaze that works on most coloured slips and 2) If
> possible make that glaze
> work with the crimson as well.
>
> Further reading indicates that maybe I should have
> tried increasing the
> Frit. In what amounts? And would that compound the
> problem with the crimson
> stain?
>
> I would sure appreciate any help you can give me
> before I rip out all of my
> hair!
>
> Carol
> in sunny Victoria
> cwaldo@bcbc.bc.ca
>
===
Antoinette Badenhorst
PO Box 552
Saltillo,Mississippi
38866
Telephone (601) 869-1651
timakia@yahoo.com
_____________________________________________________________
Do You Yahoo!?
Free instant messaging and more at http://messenger.yahoo.com
Nanci Bishof on wed 4 aug 99
What cone is the glaze?
thanks,
nanci
Ron Roy on wed 4 aug 99
Hi Carol,
Here is a version of your glaze with the expansion lowered. I have had to
change it quite a bit to lower the expansion significantly. It will be
useful to find out when this type of glaze stops crazing on the clay you
are using - so here is what to do.
Mix up 500 grams of each - the 20x5 and my revision. Do a line blend
between the two that will give you both and the three glazes in between.
Glaze #1 and glaze #5 are easy - they are the two original glazes. To get
the others you mix equal volumes of the two originals like this. 1+5 =3
(you will need twice as much of #3 for the others so make sure there is
extra in the middle one (#3). To get #2 mix equal amounts of #1 and #3 - to
get #4 mix equal amounts of #3 and #5. I just use a shop glass and I am not
trying for any great accuracy at this stage. Fire em all on the body you
are using and - hopefully you will get some that won't craze. From that
point it is easy to determine the approximate make up of the non crazing
glaze - or glazes.
You should torture them a bit to see if they are susceptible to delayed
crazing before you choose one. Freeze em all for 24 hours - then dip em in
boiling water while they are still frozen.
Beware of using these low expansion glazes on other bodies - test em by
glazing a cup inside only and do the freeze/boil.
The cloudiness is due to bubbles probably - you will see them if you use a
good magnifying glass. These bubbles are very difficult to avoid with boron
glazes - the best way to keep them at a minimum is to keep the glaze as
thin as possible consistent with the look you want and work with porcelain
type bodies.
RR variation with lower expansion.
-----------------
SILICA.............. 24.00
EPK................. 27.00
WOLAST.............. 18.00
F3134............... 27.00
CUSTER SPAR......... 4.00
----------
Total.......................100.00
FORMULA & ANALYSIS
------------------
*CaO........ .79 13.67%
*MgO........ .03 .32%
*K2O........ .02 .53%
*Na2O....... .16 3.10%
Fe2O3...... .00 .22%
TIO2....... .00 .08%
B2O3....... .30 6.52%
AL2O3...... .37 11.67%
SiO2....... 3.47 63.85%
RATIO 9.31 (original is 9.42)
EXPAN 383.05 (org - 435.85)
WEIGHT 325.60 (org - 324.12)
Let me know if you have questions - RR
>----------------------------Original message----------------------------
>Hello Clayarters,
>
>I am trying to develop a clear cone 6 glaze that works well with my clay
>body (Plainsman P300 mid-fire Porcelain) and slip decoration.
>
>I tried Tony Hansens base:
>20 Silica
>20 EPK Kaolin
>20 Wollastonite
>20 Frit 3134
>20 Custer Feldspar
>
>On my clay this glaze crazes.
>
>Test 2: Based on some recent postings, I tried addition of 5% more silica.
>On this test I used some clay that had slip decoration on it so that I was
>able to see that it not only still crazed but there appears to be tiny
>bubbles suspended throughout - could that be boron clouding? In addition, on
>one test piece I had used a slip containing 10% Mason stain - deep crimson
>and the colour was dull beige instead of Deep crimson. The other colours
>tested appeared to be okay.
>
>Please HELP!!
>
>I see this as two distinct problems. 1) To obtain a clear, well fitting
>glaze that works on most coloured slips and 2) If possible make that glaze
>work with the crimson as well.
>
>Further reading indicates that maybe I should have tried increasing the
>Frit. In what amounts? And would that compound the problem with the crimson
>stain?
>
>I would sure appreciate any help you can give me before I rip out all of my
>hair!
>
>Carol
>in sunny Victoria
>cwaldo@bcbc.bc.ca
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Dave Finkelnburg on thu 5 aug 99
Carol,
This base glaze also crazes on a clay I use, Laguna's Gray Calico.
You were on the right track to try reducing expansion. Adding silica
does that. However, this glaze already has ample silica. It also happens
to have quite a bit of calcium, which may be contributing to the crazing.
You might want to try reducing the wollastonite. It's a silica source
of calcium.
You could also test replacing some of the wollastonite with talc.
Removing half your wollastonite and replacing with an equal amount of talc
will lower the expansion about 10%, which should be enough for you. I'm not
certain if it will affect the appearance of the glaze in a way that will be
acceptable to you, though, so you'll have to test. Hope this helps.
Dave Finkelnburg
dfinkeln@cyberhighway.net
-----Original Message-----
From: Waldo, Carol
To: CLAYART@LSV.UKY.EDU
Date: Thursday, July 29, 1999 3:45 PM
Subject: Glaze problems
----------------------------Original message----------------------------
Hello Clayarters,
I am trying to develop a clear cone 6 glaze that works well with my clay
body (Plainsman P300 mid-fire Porcelain) and slip decoration.
I tried Tony Hansens base:
20 Silica
20 EPK Kaolin
20 Wollastonite
20 Frit 3134
20 Custer Feldspar
On my clay this glaze crazes.
Test 2: Based on some recent postings, I tried addition of 5% more silica.
On this test I used some clay that had slip decoration on it so that I was
able to see that it not only still crazed but there appears to be tiny
bubbles suspended throughout - could that be boron clouding? In addition, on
one test piece I had used a slip containing 10% Mason stain - deep crimson
and the colour was dull beige instead of Deep crimson. The other colours
tested appeared to be okay.
Please HELP!!
I see this as two distinct problems. 1) To obtain a clear, well fitting
glaze that works on most coloured slips and 2) If possible make that glaze
work with the crimson as well.
Further reading indicates that maybe I should have tried increasing the
Frit. In what amounts? And would that compound the problem with the crimson
stain?
I would sure appreciate any help you can give me before I rip out all of my
hair!
Carol
in sunny Victoria
cwaldo@bcbc.bc.ca
Tom List on tue 4 apr 00
Hi Glaze Gurus!!
I am setting up my own studio and have been collecting and testing
glazes for cone 6 electric firings. I have never studied chemistry and
do not have much of an understanding of glaze chemicals although I am
trying to learn. Last year I was a studio tech for a community art
center in their ceramic studio. As a result I was entitled to the scrap
clay. I brough it home in buckets. It was all the scrap from everyone
else's work all mixed together but was all highfire clays with a range
from cone 4 to 10, from Standard. Anyway this is the clay I've been
using although it is almost used up. There's no way of figuring out if
the glazes I am mixing fits the clay body mix that I have. Next problem
is that I have several glazes colors that I like in combination but they
are pulling away from the clay body in small holes exposing the clay.
Sometime on the rims but also sometimes elsewhere on the pot.
Here are the combinations I am using:
Dietrich Valley Glaze Cone 6 (A Richard Zakin formula)
Gerstley Borate 10.87
Magnesium Carb 13.04
Wallastonite 5.44
Nephline Syenite 59.78
Cedar Heights Gold Art 10.87
Add Zircopax 8.90
Cobalt Oxide 1.09
Rutile 2.17
This is a matt blue gray with slight speckles and i have no problem with
this alone. When I add clear to it is when I have problems. The clear
intesifies the blue specks in it and they become streaks and it is very
interesting effect except for the crawling away from the pot in small
holes. If I didn't like the effect of the blue streaking I would just
give up on it but it is really nice and if anyone can help me correct
this I would appreciate it. I apply this clear glaze:
Clear Glaze Cone 6 from Nelson's Ceramics
Lithuim Carb 4.8
Whiting 4.5
Zinc Oxide 11.0
Potash Feldspar 49.2
Kaolin 14.4
flint 16.1
While I am at it I am having problems with this combination as well:
Jade Green ( from Kirtland Community College - Joe Donna)
Custer Feldspar 1143
Barium Carb 570
EPK 288
Flint 285
Gerstley Borate 285
Zircopax 282
Copper Carb 147
Again I have no problem with this alone. It is a matte glaze. When I
put the followimg glaze on top I get a beautiful rich green glaze that
has a lot of debth to it but again it is crawling in small holes on the
rim and sometimes on other parts of the pot.
I add Colemanit Glossy Cone 4 to 6 (from a friend)
Frit 3134
Neph Syenite 34.9
Whiting 5.6
Gerstley Borate 5.1
Ball Clay 3.6 (I am using Kentucky Ball)
Silica 25.4
I add 3% Copper Carb.
I have been careful to clean the pot so that there is no oil from my
hands. I have also made these glazes fairly thin thinking that they
were too thick and it may have helped a little but not entirely.
If I could adjust these glazes to fit better but retain the colors I
would be very pleased. Thanks much, Nancy List, Pennsylvania
Karen and Cliff Sandlin on wed 10 oct 01
Hi everybody - these probably sound like very basic problems, but I am
getting mixed info. from the books I consult,i.e., could be overfiring;
could be underfiring, etc.
In every load of Cone 5 firing on Cone 04 bisqued ware, I use commercial
glazes: Laguna Moroccan Sand; Spectrum; Opulescence - that all say
Cone 5. My clay bodies are commercial - Cone 6, Cone 4-6, and Cone 6-9
- white, speckled, and brown. (at least 3 different clays in each load
of about 50 pcs.)
I always seem to get a few pieces with PINHOLES - even when some pieces
with the same glaze and clay in the same load do not have pinholes.
I also get cratering - particularly with Spectrum glazes. (I did try
sanding the craters down and refiring with a thin layer of the same
glaze, and that WORKED somewhat - surprisingly).
I also get 2 or 3 pieces (particularly with Opulescence) where there are
small patches that the glaze does not adhere. I do wax bottoms of pots,
but try to be extremely careful that the wax does not go anywhere but
the bottoms. I don't think it is the wax, and it only happens with
certain glazes.
I have been glaze firing at Cone 5 with a 30 min. hold. Does anyone
have any suggestions? I have a Skutt 1018 electric kiln with an
automatic controller.
Thank you.
Karen
Cindy Strnad on wed 10 oct 01
Dear Karen,
There is a lot of stuff here. Learning to glaze
takes a lot of work, and you'll be at this for a
while. (We all will--always the clay has some new
lesson to teach.) Okay, first issue:
You're using clays with different maturation
levels. If the labels are accurate (a big if),
your ^6 and ^4-^6 clays should be fine at ^6.
Probably not mature at ^4, though, nor ^5, for
that matter. The ^6-^9 clay is likely not mature
at ^6. You have to do absorption tests to be sure,
but if it can be fired to ^9, it's not good for
utilitarian work at ^5. Of course, if you're doing
indoor art, that's irrelevant. However, such a
clay, which has not reached its maturation level,
may continue to release volatile gasses, thus
causing pinholes/craters.
I've never used Laguna glazes. Many glazes do,
however, have a range of maturity. They'll look a
bit different at the different temps, but, for the
most part, they'll work at a cone or so higher or
lower. If you want to fire to ^5, you need a clay
that matures at ^5. Otherwise, try a test load
with the Laguna glazes at ^6 and see if you like
them. Be sure to protect your shelves with old
bisqued shards or such like.
Pinholes and craters. Sometimes a glaze will just
tend to do this, if it contains a lot of stuff
that gasses out. A higher firing temp/longer hold
may help, may not. Pinholes/craters can also be
caused by dusty ware. They can be caused by
outgassing from the claybody, in which case a
slower rise to your final bisque temp may be in
order. I wouldn't recommend bisquing any higher
than ^04, though. If your glaze is too thickly
applied, it will tend more toward pinholes and
craters. In this case, the flaws will cluster
around the inside base of a bowl, cup, etc., where
the glaze has puddled a bit.
Your last problem is probably crawling--hard to
say without seeing it, but that's what it sounds
like. It can be caused by the composition of the
glaze (one example: too high a shrinkage
factor--perhaps too much clay content), too thick
a coat on your glazed ware, grease, etc. spots on
the ware. If you see cracks in the dried glaze,
you will most likely have crawling. If you do this
on purpose, it's called a lichen glaze. If not,
it's called a bummer. Sometimes, if you "heal" the
cracks by brushing over them with a finger, you
can prevent crawling from happening in small areas
where you've inadvertently gotten the glaze
thicker than it should be.
Best wishes,
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
Karen and Cliff Sandlin on thu 11 oct 01
Thanks Joanne: I have been rinsing the bisqued pieces, but will also
try firing at Cone 6 instead of 5. I will thin my glazes more. Didn't
do it before because I mistakenly thought I would change the composition
of the glaze.
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG] On
Behalf Of Joanne Van Bezooyen
Sent: Thursday, October 11, 2001 10:34 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: glaze problems
Hi Karen,
I use some Laguna glazes and discovered that for my kiln, cone 6 melts
better. I usually thin the glazes down a bit with distilled water and
apply
several thin coats. Are you rinsing the bisqued pieces before you glaze
to
get the 'dust' off?
Joanne L. Van Bezooyen
Art Gecko Designs
11220 E. Via Madre
Tucson, Arizona, USA 85749
(520)749-1685 home
(520) 760-1584 studio and fax
http://www.artgeckotile.com
----- Original Message -----
From: "Karen and Cliff Sandlin"
To:
Sent: Wednesday, October 10, 2001 7:28 AM
Subject: [CLAYART] glaze problems
> Hi everybody - these probably sound like very basic problems, but I am
> getting mixed info. from the books I consult,i.e., could be
overfiring;
> could be underfiring, etc.
>
> In every load of Cone 5 firing on Cone 04 bisqued ware, I use
commercial
> glazes: Laguna Moroccan Sand; Spectrum; Opulescence - that all say
> Cone 5. My clay bodies are commercial - Cone 6, Cone 4-6, and Cone
6-9
> - white, speckled, and brown. (at least 3 different clays in each load
> of about 50 pcs.)
>
> I always seem to get a few pieces with PINHOLES - even when some
pieces
> with the same glaze and clay in the same load do not have pinholes.
>
> I also get cratering - particularly with Spectrum glazes. (I did try
> sanding the craters down and refiring with a thin layer of the same
> glaze, and that WORKED somewhat - surprisingly).
>
> I also get 2 or 3 pieces (particularly with Opulescence) where there
are
> small patches that the glaze does not adhere. I do wax bottoms of
pots,
> but try to be extremely careful that the wax does not go anywhere but
> the bottoms. I don't think it is the wax, and it only happens with
> certain glazes.
>
> I have been glaze firing at Cone 5 with a 30 min. hold. Does anyone
> have any suggestions? I have a Skutt 1018 electric kiln with an
> automatic controller.
>
> Thank you.
>
> Karen
>
>
________________________________________________________________________
____
__
> 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.
Karen and Cliff Sandlin on thu 11 oct 01
Thanks Paul. I will give all these things a try. I have been using a
soak on the glaze firing, but did not think to do it on the bisque. How
long do you think? Would 30 min. be enough? I bisque at 04.
Karen
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG] On
Behalf Of Paul Gerhold
Sent: Thursday, October 11, 2001 10:12 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: glaze problems
Karen,
There are a couple of things you might want to try:
1. Try wiping your pots with clean water before glazing. This will
eliminate
any possible dust from the pot surface and helps adhesion with some
glazes.
2. If you are applying your glazes by brushing try thinning the glazes
and
applying more coats.
3. Try using a soak when you are bisque firing and possibly try a higher
bisque.
4. Check the archives. Lots of past discussionon this topic.
Good Luck
Paul
________________________________________________________________________
______
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.
Paul Gerhold on thu 11 oct 01
Karen,
There are a couple of things you might want to try:
1. Try wiping your pots with clean water before glazing. This will eliminate
any possible dust from the pot surface and helps adhesion with some glazes.
2. If you are applying your glazes by brushing try thinning the glazes and
applying more coats.
3. Try using a soak when you are bisque firing and possibly try a higher
bisque.
4. Check the archives. Lots of past discussionon this topic.
Good Luck
Paul
Joanne Van Bezooyen on thu 11 oct 01
Hi Karen,
I use some Laguna glazes and discovered that for my kiln, cone 6 melts
better. I usually thin the glazes down a bit with distilled water and apply
several thin coats. Are you rinsing the bisqued pieces before you glaze to
get the 'dust' off?
Joanne L. Van Bezooyen
Art Gecko Designs
11220 E. Via Madre
Tucson, Arizona, USA 85749
(520)749-1685 home
(520) 760-1584 studio and fax
http://www.artgeckotile.com
----- Original Message -----
From: "Karen and Cliff Sandlin"
To:
Sent: Wednesday, October 10, 2001 7:28 AM
Subject: [CLAYART] glaze problems
> Hi everybody - these probably sound like very basic problems, but I am
> getting mixed info. from the books I consult,i.e., could be overfiring;
> could be underfiring, etc.
>
> In every load of Cone 5 firing on Cone 04 bisqued ware, I use commercial
> glazes: Laguna Moroccan Sand; Spectrum; Opulescence - that all say
> Cone 5. My clay bodies are commercial - Cone 6, Cone 4-6, and Cone 6-9
> - white, speckled, and brown. (at least 3 different clays in each load
> of about 50 pcs.)
>
> I always seem to get a few pieces with PINHOLES - even when some pieces
> with the same glaze and clay in the same load do not have pinholes.
>
> I also get cratering - particularly with Spectrum glazes. (I did try
> sanding the craters down and refiring with a thin layer of the same
> glaze, and that WORKED somewhat - surprisingly).
>
> I also get 2 or 3 pieces (particularly with Opulescence) where there are
> small patches that the glaze does not adhere. I do wax bottoms of pots,
> but try to be extremely careful that the wax does not go anywhere but
> the bottoms. I don't think it is the wax, and it only happens with
> certain glazes.
>
> I have been glaze firing at Cone 5 with a 30 min. hold. Does anyone
> have any suggestions? I have a Skutt 1018 electric kiln with an
> automatic controller.
>
> Thank you.
>
> Karen
>
>
____________________________________________________________________________
__
> 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.
Jim Mason on fri 12 oct 01
Dear Karen,
One other thing that I don't think has been mentioned regards the use of wax.
I have had a tendency to touch the hot wax to smear it into areas that are
not covered well. Obviously, this gets wax on my fingers and presumably then
onto the pots wherever else that I might touch them. Since I have been
consciously avoiding this, I have seen much less of the type of crawling that
you mentioned. I hope that this of help.
Best regards,
Jim Mason,
Gibsonville NC
Wade Blocker on fri 12 oct 01
Karen,
If you are using the cone 6 to 9 clay from Laguna, you will have glaze
problems. I used that clay and the glazes would not only crackle, but
actually crack. The firing range for that clay is just too wide.The cone 4
to 6 clays are what one should use if you fire to cone 5 or a bit higher.
Thinning a glaze too much might end up with a rough surface, unless it is a
transparent gloss glaze. Matt glazes have to be applied with a thicker
coat. If the pot ends up with a few bare spots or pinholing, reglaze that
area with either the same glaze or a different glaze, and refire. This will
generally result in a perfectly glazed pot. Mia in ABQ
funkfamily on wed 26 mar 03
Hi everyone- I'm a pretty new potter, still doing it mostly as a hobby, =
with a "real" job to pay the bills. I just started mixing my own glazes =
last fall, and I one of the first I tried was "Blue Hare's Fur". It =
came out gorgeous the first few times I fired it. Then I tried a recipe =
for "Blueberry" that uses Randi's red base and colored with cobalt oxide =
and black nickel oxide. I had used it before with great results. I =
thought I had two great glazes to work with. So, in the meantime, I had =
bought "Mastering Cone 6 Glazes" and was reading about programming the =
kiln for slower cooling. =20
So, all of a sudden I have these problems. On slow cooling, Blue =
hare's fur loses its beautiful deep blue variation and goes really pale =
blue with poop green undertones. But also, the blueberry is showing =
blisters like the worst case of acne you can imagine! I tried the next =
kiln with normal cooling after the pre-programmed cone 6 firing, blue =
hare's fur got most of the color back, but now it's full of pinholes, =
and the blueberry is no better! There's one other variable to consider, =
that I got a different batch of gerstley from another source. Could =
that be the problem?
To make matters worse, I have lost the Mastering Cone 6 Glazes book, =
I had tried a few of the non-gerstley glazes and I know that I should be =
going in that direction, but I liked these two glazes so much! Can =
anyone offer any insight?
Valerie Hawkins on thu 27 mar 03
Are you using witness cones? My kiln overfires when using R&J's firing
schedule. I've dropped back my top temp. Also, I found that some of my
glazes look better when fast fired, so I've seperated my glazes into two
groups for firing purposes.
Valerie
Charlotte
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of funkfamily
Sent: Wednesday, March 26, 2003 9:27 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Glaze problems
Hi everyone- I'm a pretty new potter, still doing it mostly as a hobby, with
a "real" job to pay the bills. I just started mixing my own glazes last
fall, and I one of the first I tried was "Blue Hare's Fur". It came out
gorgeous the first few times I fired it. Then I tried a recipe for
"Blueberry" that uses Randi's red base and colored with cobalt oxide and
black nickel oxide. I had used it before with great results. I thought I
had two great glazes to work with. So, in the meantime, I had bought
"Mastering Cone 6 Glazes" and was reading about programming the kiln for
slower cooling.
So, all of a sudden I have these problems. On slow cooling, Blue hare's
fur loses its beautiful deep blue variation and goes really pale blue with
poop green undertones. But also, the blueberry is showing blisters like the
worst case of acne you can imagine! I tried the next kiln with normal
cooling after the pre-programmed cone 6 firing, blue hare's fur got most of
the color back, but now it's full of pinholes, and the blueberry is no
better! There's one other variable to consider, that I got a different
batch of gerstley from another source. Could that be the problem?
To make matters worse, I have lost the Mastering Cone 6 Glazes book, I
had tried a few of the non-gerstley glazes and I know that I should be going
in that direction, but I liked these two glazes so much! Can anyone offer
any insight?
____________________________________________________________________________
__
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.
william schran on thu 27 mar 03
Funkfamily wrote about problems with "blue hare's fur" and
"blueberry" glazes. Said source of gerstley borate had changed.
Change of any material can often be problematic. Need to run tests
any time a new material is introduced.
I've found the hare's fur glaze (original with GB) performs better at
cone 5 with a somewhat faster cooling. When fired in our 21/2" brick
walled kiln it performs well. Fired in the 3" walled kiln, that cools
slower, the glaze goes towards the greener colors.
Bill
John Hesselberth on thu 27 mar 03
On Wednesday, March 26, 2003, at 09:26 PM, funkfamily wrote:
> There's one other variable to consider, that I got a different batch
> of gerstley from another source. Could that be the problem?
Hi funkfamily,
I'd address you by your real name, but couldn't find one in your
message. Yes, a different batch of Gerstley Borate could very
definitely be part or all of your problem. It has an extremely variable
composition lot to lot--sometimes even bag to bag. That was the
primary reason we don't have it as an ingredient in any of our glazes
in Mastering Cone 6 Glazes.
Regards,
John
http://www.frogpondpottery.com
http://www.masteringglazes.com
Ron Roy on sat 27 sep 03
Hi Carrie,
My standard advice for those who want to do majolica is to consider doing
it at cone 6. If the glaze book you have is Mastering Cone 6 Glazes you
will find an excellent cone 6 Majolica type glaze on page 108.
It makes so much sense to me to do it at cone 6 - you can have a vitrified
body and vivid colour as well - and the ware can be vitrified enough to be
fully functioal as well.
As for the Jade Green running - there are two ways to fix that - adding
alumina will stop the running - you can also substitute higher viscosity
fluxes for lower. It's a more complicated way but if you know how to use a
calculation program it gets a lot easier.
By the way - the Jade Green is seriously short of silica and has a lot of
copper - an unstable glaze - it should not be used as a liner glaze. It is
also going to craze on just about any body you put it on. Try the lemon
test on it - it's going to change colour.
I have raised the alumina in the following revision but - it will still be
unstable and it will still craze - if it still runs send it back and I'll
try again. I din't have much hope that it will look the same and because of
all that zinc - you may be in for a pinholing problem as it gets stiffer.
My best advice on this one - find another.
G200 - 34.0
Strontium Carb. - 18.0
EPK - 13.0
Silica - 13.0
Gerstley Borate - 9.0
Zinc oxide - 8.0
Copper carb - 4.90
Total - 99.90 - same as the original
Don't attach my name to it - I would never recommend such a glaze without
at least saying it was totaly unsuitable for food bearing surfaces.
If you try it - only do a 200 gram batch and watch out for running just in case.
RR
>My studio pals have encouraged me to present a few dilemas to you in the
>hopes of making some sound glazes.
>
>I have two recipes which are problematic, but close to being what we need.
>
>The first is my attempt to find a Majolica glaze that will fire at cone
>06. I finally did get a hold of one that fired out at that temperature but
>it has many faults. On behalf of the recipe I will say that when done
>perfectly it is right on the money.
>
>The recipe is as follows:
>
>Frit 785 60%
>
>Kentucky Ball 10
>
>Frit 3124 20
>
>Zircopax 10
>
>Tin 5
>
>
>
>Even though it's l05% it is the recipe as given to me. I found the Frit
>785 (finally) at Standard Ceramic. It's a bit pricey for our budget but I
>wanted to try it. At it's very best it is a fine look. I guess to
>generalize the problem, it would be to say that it is a difficult glaze to
>achieve good coverage with and it is a dusty one to work with. Brushing it
>shows the brush lines, it doesn't level very well in the firing when
>dipped, even when dry finger-sanded. The best application is achieved by
>spraying. the smudging which seems unavoidable when sprayed is the next
>headache. My favorite recipe is the one promoted by Linda Arbuckle in the
>Axner catalogue but it is a Cone 04 and this group doesn't fire to that
>temp. I did add CMC to the glaze which seems to help stiffen it when
>dipped, but not when sprayed. I can't avoid finger marks in handling
>after spraying even when I wait til it's dead dry. I'd love a substitute
>for the obscure Frit 785 and a more agreeable recipe. Is there hope or
>should I abandon the 06 majolica idea altogether?
>
>The other glaze problem is this one:
>
>Jade Green Cone 6
>
>as posted in Clayart
>
>G 200 38.1
>
>Strontium 19.0
>
>EPK 9.6
>
>Flint 9.5
>
>Gerstley B 9.4
>
>Zinc Ox 9.4
>
>Copper Carb 4.9
>
>
>
>It's a beauty, but it runs. What to do?
>
>Thank you so much. And let me be the next in line to tell you how excited
>we are by your new book on glazes. We are testing several of them (the
>cone 6 oxidation) this coming week and have high hopes.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Gary Harvey on tue 6 jan 04
I am new to glaze making. I tested a recipie for glaze 6 clear that I found
in Tony Birks "The complete Potter's commanion" Johannes Peters Glaze
consist of 72 nepheline syenate, 9 calcium borate, 6 white stoneware clay,
and 7 talc. I used gillespie borate for the calcium borate and OM 4 for the
white stoneware clay. The glaze crazed like crazy. (I will send a photo to
anyone that is interested) Can I use the white clay that is my normal clay
and do any of you think that will fix the crazing problem? I want to use
this on foodware. AND what amount of Glaze should I make up as a test amount?
william schran on tue 6 jan 04
Gary wrote:> I used gillespie borate for the calcium borate and OM 4 for the
white stoneware clay. The glaze crazed like crazy. (I will send a photo to
anyone that is interested) Can I use the white clay that is my normal clay
and do any of you think that will fix the crazing problem? I want to use
this on foodware. AND what amount of Glaze should I make up as a test amount?<
There are so many variables that it's difficult to point to one thing
that causes or cures your crazing issues. You'll have to conduct
tests. Could be the clay body and how this glaze fits or doesn't fit
it.
That said, I would expect a glaze with such a high percentage of
Neph. Sy. to craze.
You could try your clay body or simply a white clay such as EPK.
Suggest test of 100 grams each.
Bill
Scott Ackerman on tue 6 jan 04
I haven't checked this out in Insight yet, but the amount of Nepheline
Syenate in this is probably the culprit. Nepheline Syenate is high in =
sodium
and sodium has a very high coefficient of expansion. You need to source =
your
fluxes from other lower expansion sources like magnesium as well. You =
have
some magnesium in talc but not nearly enough to counteract all of the =
sodium
in the Nepheline Syenate.
"Every improvement in the standard of work men do is followed swiftly =
and
inevitably by an improvement in the men who do it" - William Morris
=20
Scott Ackerman
1133 Riverside
Suite B
Fort Collins, CO 80524
970-231-9035
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Gary Harvey
Sent: Tuesday, January 06, 2004 8:50 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Glaze problems
I am new to glaze making. I tested a recipie for glaze 6 clear that I =
found
in Tony Birks "The complete Potter's commanion" Johannes Peters Glaze
consist of 72 nepheline syenate, 9 calcium borate, 6 white stoneware =
clay,
and 7 talc. I used gillespie borate for the calcium borate and OM 4 for =
the
white stoneware clay. The glaze crazed like crazy. (I will send a photo =
to
anyone that is interested) Can I use the white clay that is my normal =
clay
and do any of you think that will fix the crazing problem? I want to =
use
this on foodware. AND what amount of Glaze should I make up as a test
amount?
_________________________________________________________________________=
___
__
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 7 jan 04
Hi Gary,
First of all - the glaze only adds up to 94 - is that correct?
It will not matter what clay you use - you will not cure the crazing that way.
I agree with others - find a more balanced glaze to start with - there are
plenty around. Try to pick one that is stable and durable if you are
planning to use it as a liner glaze.
Using a glaze with that much Neph Sy is begging for deflocculation problems
with the glaze slop - If you must use Neph Sy keep the amount low and keep
the raw clay higher to prevent hard panning.
Neph Sy works against a stable glaze slop in two ways - it provides soluble
sodium (the defloccer) and because it brings a fair amount of alumina with
it - you are limited in the amount of clay (the suspender) in the glaze.
This glaze is very high in Alumina by the way - I wonder if it is properly
melted.
If it's a clear glaze - (I would guess not) - then adding silica would be
the answer to stop the crazing - but because the alumina is so high I would
guess it would not melt properly before the crazing stopped.
RR
>I am new to glaze making. I tested a recipie for glaze 6 clear that I found
>in Tony Birks "The complete Potter's commanion" Johannes Peters Glaze
>consist of 72 nepheline syenate, 9 calcium borate, 6 white stoneware clay,
>and 7 talc. I used gillespie borate for the calcium borate and OM 4 for the
>white stoneware clay. The glaze crazed like crazy. (I will send a photo to
>anyone that is interested) Can I use the white clay that is my normal clay
>and do any of you think that will fix the crazing problem? I want to use
>this on foodware. AND what amount of Glaze should I make up as a test amount?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Scott Paulding on sun 20 nov 05
hello all,
i have a glaze problem i wanted to share with you all. back east, there
were two glazes in particular that i used frequently: yellow salt and chun
white. here are the recipes:
chun white:
kona f4 31
wollastonite 30
silica 15
grolleg 10
zircopax 7
dolomite 5
tin o2 2
+bentonite 2 (per richard aerni's suggestion)
yellow salt:
Neph Sy 64
Dolomite 21
zircopax 16
OM4 4
Bentonite 4
Also add RIO 1
now that i'm on the west coast, what's happening is that both glazes,
overnight, form very solid masses on the bottom of the bucket. it's really
strange. both glazes contain a healthy amount of bentonite, and i've even
added extra, yet then both clump to the bottom of the bucket.
any ideas what might be different ont he west coast vs. the east? my first
thought was the water, but any/all of the raw mats are probably different
too. how do i fix this? thanks,
-scott
"Do you realize...that happiness makes you cry?"
-The Flaming Lips
__________________________________
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Robert Arnold on mon 27 feb 12
All, I am having some problems with my glazes and I cannot figure out what
to try next and was hoping someone might be able to help me. I have
attached a link to a couple of photos that show the problem. I have also
included a photo of a Cone 6 test cone that was placed right in the center
of the kiln by height and depth. Two of the glazes in the photos are
commercially available cone 6 matte glazes and the other is my own cone 6
glaze. I am firing electric oxidation and below is my latest firing
schedule. I have been having these problems with the pinholes/bubbles for
some time and I am at a loss for what to try next. I am using my own clay
mix. I bisque to cone 04 at slow speed. I dip all of my glazes and the
particular ones in these photos are pretty thin so I do not think it is a
problem with the glaze being too thick. I am using a Paragon front loading
kiln with a digital controller.Photos of the glaze defects along with a
photo of the test cone can be seen on my Flickr page at
http://www.flickr.com/photos/thedoghouseworkshop/
Firing Schedule
Rate Temperature Hold
100 220 0
400 2000 0
190 2190 15
500 1900 0
125 1500 0
Off
Thanks, Robert
The Dog House Workshop
June on tue 28 feb 12
Looks to me like you may be firing too fast, particularly from the point wh=
en your glaze starts to melt, to maturity. Looks like fast firing is causin=
g a lot of boiling, causes the big bubbles, then not enough slow/soaking ti=
me to heal them over.
Warm regards,
June
http://wwww.shambhalapottery.blogspot.com
http://groups.yahoo.com/group/sodasaltfiring/
http://www.shambhalapottery.com
----- Original Message -----
From: Robert Arnold
To: Clayart@LSV.CERAMICS.ORG
Sent: Tue, 28 Feb 2012 04:32:44 -0000 (UTC)
Subject: Glaze Problems
All, I am having some problems with my glazes and I cannot figure out what
to try next and was hoping someone might be able to help me. I have
attached a link to a couple of photos that show the problem. I have also
included a photo of a Cone 6 test cone that was placed right in the center
of the kiln by height and depth. Two of the glazes in the photos are
commercially available cone 6 matte glazes and the other is my own cone 6
glaze. I am firing electric oxidation and below is my latest firing
schedule. I have been having these problems with the pinholes/bubbles for
some time and I am at a loss for what to try next. I am using my own clay
mix. I bisque to cone 04 at slow speed. I dip all of my glazes and the
particular ones in these photos are pretty thin so I do not think it is a
problem with the glaze being too thick. I am using a Paragon front loading
kiln with a digital controller.Photos of the glaze defects along with a
photo of the test cone can be seen on my Flickr page at
http://www.flickr.com/photos/thedoghouseworkshop/
Firing Schedule
Rate Temperature Hold
100 220 0
400 2000 0
190 2190 15
500 1900 0
125 1500 0
Off
Thanks, Robert
The Dog House Workshop
William & Susan Schran User on tue 28 feb 12
On 2/27/12 11:32 PM, "Robert Arnold" wrote:
>All, I am having some problems with my glazes and I cannot figure out what
>to try next and was hoping someone might be able to help me. I have
>attached a link to a couple of photos that show the problem... I have
>been having these problems with the pinholes/bubbles for
>some time and I am at a loss for what to try next...
>http://www.flickr.com/photos/thedoghouseworkshop/
>
Robert, First thing to try is adding a 30 minute hold at the end of your
bisque firing.
Have you tried the glazes on other clay bodies? This might help determine
whether the issue is the glaze or the clay, though since it happens to
both commercial and your glaze, that might point to the clay.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
>
David Woof on tue 28 feb 12
Hi Arnold=3D2C
From what I read you have been trying different firing schedules to no avai=
=3D
l. It seems that you may need to investigate elsewhere among the sometimes =
=3D
daunting variables.
please give us your glaze and clay body recipes as raw materials lists with=
=3D
percentages.
There may be clues in the materials list.
Also have you changed clay bodies? What would happen if you did change your=
=3D
clay body now as a control=3D2C or subbed a material as a trial?
Communicate with the manufacturers. Are you and the manufacturer both keepi=
=3D
ng up on the changes that occur in mined raw materials for both glazes and =
=3D
bodies.
What suspect material(s) may your glazes and bodies hold in common.
Start looking down these paths and let us look with you.
None of your efforts will be wasted=3D3B even the dead ends and apparent fa=
il=3D
ures are all part of a broadening foundation for your ceramic education.
David Woof
__________________________________________________________
12. Glaze Problems
Posted by: "Robert Arnold" rwarnoldjr@GMAIL.COM
Date: Mon Feb 27=3D2C 2012 8:53 pm ((PST))
All=3D2C I am having some problems with my glazes and I cannot figure out w=
ha=3D
t
to try next and was hoping someone might be able to help me. I have
attached a link to a couple of photos that show the problem. I have also
included a photo of a Cone 6 test cone that was placed right in the center
of the kiln by height and depth. Two of the glazes in the photos are
commercially available cone 6 matte glazes and the other is my own cone 6
glaze. I am firing electric oxidation and below is my latest firing
schedule. I have been having these problems with the pinholes/bubbles for
some time and I am at a loss for what to try next. I am using my own clay
mix. I bisque to cone 04 at slow speed. I dip all of my glazes and the
particular ones in these photos are pretty thin so I do not think it is a
problem with the glaze being too thick. I am using a Paragon front loading
kiln with a digital controller.Photos of the glaze defects along with a
photo of the test cone can be seen on my Flickr page at
http://www.flickr.com/photos/thedoghouseworkshop/
Firing Schedule
Rate Temperature Hold
100 220 0
400 2000 0
190 2190 15
500 1900 0
125 1500 0
Off =3D
Steve Slatin on tue 28 feb 12
Robert -- I suspect you'll have to test different things to determine the=
=3D
=3D0Acause of the flaw.=3DA0 I see you're firing to ^6 just touching, and s=
ince=3D
two=3D0Aof your glazes are commercial and rated to ^6 I suspect your top f=
ir=3D
ing=3D0Atemperature is not the problem.=3DA0 And you're bisqueing to ^06 so=
it'=3D
s=3D0Aprobably not your bisqueing that's the problem.=3D0A=3DA0=3D0AThat le=
aves the=3D
clay, the glazes, and the firing ramp.=3DA0 =3D0A=3DA0=3D0AOne thing you c=
an do is=3D
to get a reliable ^6 clay OTHER THAN =3D0AYOUR USUAL CLAY and try a batch =
of=3D
it -- if you get the same =3D0Aresults, your clay is most likely not the p=
ro=3D
blem.=3D0A=3DA0=3D0AIt is, of course, possible, that the glazes are the pro=
blem -=3D
- I note that=3D0Ayou feel you glaze thin, so overly thick glaze should not=
b=3D
e the problem=3D0Ahere.=3DA0 As in a few cases an overly thin glaze can lea=
d to=3D
pinholing or=3D0Acratering, though, there's an easy test to see if a thick=
er=3D
application=3D0Awould resolve the problem.=3DA0 Bisque some ware, do your =
regu=3D
lar glazing,=3D0Aand then re-dip the piece (preferably only over a portion =
of=3D
the surface).=3D0A=3DA0=3D0AIf your result is pinholing and cratering on t=
he thi=3D
nner parts and none=3D0Aon the thicker parts, a thicker glaze application i=
s =3D
your likely solution.=3D0A=3DA0=3D0AThe last possibility I can think of is =
your f=3D
iring ramp.=3DA0 Your first three=3D0Asegments make the ^6 touch.=3DA0 Afte=
r that=3D
you have essentially a crash=3D0Acool for almost 300 degrees F.=3DA0 Try a=
cra=3D
sh for 80 degrees F (a 500=3D0Adegrees per hour rate) and then a hold, or b=
eg=3D
in your 150 F per hour=3D0Adrop at that point.=3DA0 This will give the glaz=
e ti=3D
me to heal over pinholes,=3D0Aand maybe even craters.=3DA0 (If the problem =
is i=3D
nsufficient time to heal.)=3D0A=3DA0=3D0AI'm sure we'd all be interested to=
hear =3D
what your solution is.=3D0A=3DA0=3D0ASteve Slatin -- =3D0A=3D0A=3D0AN48.088=
6450=3D0AW123.=3D
1420482=3D0A=3D0A=3D0A________________________________=3D0AAll, I am having=
some pr=3D
oblems with my glazes and I cannot figure out what=3D0Ato try next and was =
ho=3D
ping someone might be able to help me. I have=3D0Aattached a link to a coup=
le=3D
of photos that show the problem. I have also=3D0Aincluded a photo of a Con=
e =3D
6 test cone that was placed right in the center=3D0Aof the kiln by height a=
nd=3D
depth. Two of the glazes in the photos are=3D0Acommercially available cone=
6=3D
matte glazes and the other is my own cone 6=3D0Aglaze.
Robert Arnold on tue 28 feb 12
All, thanks for the response. It would appear that the consensus is I
should slow down my firing schedule especially at the top and for the first
part of the cooling at least. It probably would have helped if I had
provided a little more information about my work. I have been working with
ceramics for about 2 1/2 years now. I create models for all of my pieces
from wood that I have either turned on the lathe or carved. I then make my
own molds from these models for casting. I mix my own clay because when I
started working with ceramics I didn't know any better. Since I am
self-taught I started looking around for information about Cone 6 casting
bodies. There is only one supplier here in Las Vegas and they only carried
low-fire and cone 10 porcelain in 1 gal. and 5 gal. containers. I didn't
like the look of either of these clays so I figured I would just make my
own, It couldn't be that hard. I was wrong. Apparently the large ceramic
manufacturers such as Kohler and others are hesitant to share clay body
recipes. I read everything I could find on casting bodies and started
testing. It seemed every time I thought I found what would be a good clay
body for me I mixed a larger batch and well, at the start things did not go
so well. I have had to dump anywhere in the neighborhood of 450 to 500
gallons of various slips. I have now reached a point where I have what I
think is a good casting body in terms of all of the properties relevant to
casting. I have gotten pretty good at making my own molds now, thank
goodness plaster is cheap. I started off with commercially available glazes
but then decided I would ike to make my own glazes since I couldn't really
find ones I felt were a good match for my pieces,and after all how hard
could it be. In case you haven't picked up on it yet I am a bit
hard-headed. I have had mixed luck with the glazes. I purchased Mastering
Cone 6 Glazes and the Glazemaster software and went to town. The problem
with the pinholes ha beeen eating away at me since I started. I would have
some kiln loads where half of the pieces came out great and half looked
like crap. Same clay, casting, bisque, glazing method and glaze but
drastically different results. At one time or another I have had most of
the glazes I have tried come out well so my thinking is the problems are
more likely related to either the firing or the clay body. I have tried a
lot of different firing schedules and had mixed results. If anyone is
interested in seeing my progress over the past two years you can take a
look here: http://thedoghouseworkshop.com/ I will post some photos of how
the next test goes.
Thanks, Robert
The Dog House Workshop
ronroy@CA.INTER.NET on fri 2 mar 12
Hi Robert,
I need to see your clay recipe - that would be my best guess as to
where to start.
I can compare it to many cone 6 bodies that I have data for and see if
it is being over fired.
RR
Quoting Robert Arnold :
> All, I am having some problems with my glazes and I cannot figure out wha=
t
> to try next and was hoping someone might be able to help me. I have
> attached a link to a couple of photos that show the problem. I have also
> included a photo of a Cone 6 test cone that was placed right in the cente=
r
> of the kiln by height and depth. Two of the glazes in the photos are
> commercially available cone 6 matte glazes and the other is my own cone 6
> glaze. I am firing electric oxidation and below is my latest firing
> schedule. I have been having these problems with the pinholes/bubbles for
> some time and I am at a loss for what to try next. I am using my own clay
> mix. I bisque to cone 04 at slow speed. I dip all of my glazes and the
> particular ones in these photos are pretty thin so I do not think it is a
> problem with the glaze being too thick. I am using a Paragon front loadin=
g
> kiln with a digital controller.Photos of the glaze defects along with a
> photo of the test cone can be seen on my Flickr page at
>
> http://www.flickr.com/photos/thedoghouseworkshop/
>
>
> Firing Schedule
> Rate Temperature Hold
> 100 220 0
> 400 2000 0
> 190 2190 15
> 500 1900 0
> 125 1500 0
> Off
>
>
> Thanks, Robert
> The Dog House Workshop
>
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