Malone & Dean McRaine on sat 13 dec 97
(was Glaze Meltdown-aaaarrgh)
Aloha all: As you can see from my title my situation hasn't improved. I'm
getting desperate. It's the Christmas season and my main product line has
committed glaze suicide. I've done two firings of tests and am no closer to
an answer. Here's the story form the beginning.
I've been using this glaze for 7-8 years, here in Hawaii and previouly in
Washington. I've fired it in wood, gas, and electric kilns with consistant
results.
Vermillion Brick Red ^9-10 Oxidation
50 Cornwall Stone
25 EPK
25 Whiting
8 Red Iron Oxide
This usually fires to a matt dull red to ochre. I've had it up to ^11-12
and it has retained a matt surface. So I mixed up a new bucket last month
and fired it and everything came out runny gloss amber. Kind of like a bad
ash gloss. Uuuuugly! There were a few spots on the center of the bottoms of
a few pots that resembled the original glaze. It's as though the character
of the glaze is still there but it's been fired 4 cones too hot. The glaze
is sometimes thinner in the center of the bottom from wiping off the foot.
I thought I might have a new batch of whiting with increased fluxing power
and so borrowed some from a friend-no difference. Some clayarters suggested
that my water in my new country home migh be the culprit so I tried a test
with distilled, still no help. I line blended the EPK up to 35-no change. I
reduced the whiting in increments to 16-still ugly. I picked up the current
thread on Cornwall Stone and queried Stephen Mills about the variability of
Cornwall Stone but he didn't think a change in the CS could account for my
problem, the composition of Cornwall Stone is more consistant than that. I
recently coated my kiln with ITC 100 and I'm wondering if it's possible that
this could have had some effect. I had fired with the ITC 3 times with good
results before this happened so I didn't immediately think such a drastic
change could be the result of the new coating.
At this point I'm willing to consider just about anything, a new religion,
voodoo, name it-I'll try it.
If anybody has any help for me I'd really appreciate it.
Dean from Kauai, where I'm not thinking much about the weather right now.
Karl P. Platt on sun 14 dec 97
Cornwall Stone is un ugly cousin of Ghastly Borate. Obviously while the
glaze sat around something dissolved -- likely alkali. The material was
more ready to react.
Make a new batch
Karl P. Platt on sun 14 dec 97
I read the post too fast before -- seems you did make it over...with the
same materials.
Cornwall Stone is, indeed, a highly variable material.
Iron oxides, too, can vary markedly in particle size distribution.
DONPREY on sun 14 dec 97
DEAN,
According to your post, you have checked the whiting and cornwall stone. Have
you checked out the EPK? Any reason to suspect that you are in fact not using
EPK? It is hard to imagine the change you are seeing would happen from
anything except a completely wrong material.
I don't remember from your earlier post....are you firing in an electric kiln?
I may get a chance to test this recipe in a cone 10 reduction firing in the
next week or so. I'll let you know if I get that done.
Don Prey in Oregon
Leslie McPherson on sun 14 dec 97
I know this might sound stupid Dean...but you said you would try anything!
It's not voodoo...how about trying applying it thinner and see what
happens. If you say it looks like an ash glaze too thick, try applying it
like an ash glaze; thin. Just a thought...
aloha.
p.s. just watched your program that you and your wife did with Molly...it
was great, good thing to turn the public on to!
R12396 on sun 14 dec 97
Hello,
Well, it could be the ITC coating, why not try firing lower then you have
been? Maybe after 3 firing on the new ITC coating, this could have cause it to
become "seasoned" now enabling to give better reflective(heat)
properties?...just a thought..R12396..in Sacto,Ca
Craig Martell on tue 16 dec 97
Hi Dean:
I read the posts on your glaze and thought I might offer something for
experiment that may help.
Maybe The Cornwall Stone is at fault and maybe not. Below is a recalculated
formula and receipe for the Vermillion glaze without Cornwall. The formula
is almost identical to the original but I took the liberty of raising the
silica to above 3.0 from about 2.53, which is a bit low. So, you might want
to try this one as a test, and see what kind of melt and surface you get.
Another thing to consider is the cooling cycle. This is a .8 Limestone
matt, with alumina contributing to mattness as well. Lime matts, if cooled
too fast will not develop the anorthite crystals that devitrify the glaze
and give it the matt surface, and they will be glassy. Are you cooling the
glaze faster than before?
The only difference in the formula below is .01 MgO is gone and there is .02
more moles of KNaO and a bit more silica than in the original formula. Just
add the usual amount of Iron.
regards, Craig Martell-Oregon
Untitled Recipe 1
CUSTER FELDSPAR 19.17 CaO 0.83*
WHITING 23.72 MgO 0.00*
EPK KAOLIN 28.84 K2O 0.08*
SODA FELDSPAR 8.08 Na2O 0.09*
SILICA 20.19 Fe2O3 0.00
======== TiO2 0.00
100.00 Al2O3 0.54
SiO2 3.05
Cost/kg 0.11
Si:Al 5.66
SiB:Al 5.66
Expan 7.15
Judith Enright on wed 17 dec 97
Craig -- refresh our memories? Is this ^6?
______________________________ Reply Separator _________________________________
Subject: Re: Glaze Nightmare
Author: Craig Martell at Internet
Date: 12/16/97 9:39 AM
----------------------------Original message----------------------------
Hi Dean:
I read the posts on your glaze and thought I might offer something for
experiment that may help.
Maybe The Cornwall Stone is at fault and maybe not. Below is a recalculated
formula and receipe for the Vermillion glaze without Cornwall. The formula
is almost identical to the original but I took the liberty of raising the
silica to above 3.0 from about 2.53, which is a bit low. So, you might want
to try this one as a test, and see what kind of melt and surface you get.
Another thing to consider is the cooling cycle. This is a .8 Limestone
matt, with alumina contributing to mattness as well. Lime matts, if cooled
too fast will not develop the anorthite crystals that devitrify the glaze
and give it the matt surface, and they will be glassy. Are you cooling the
glaze faster than before?
The only difference in the formula below is .01 MgO is gone and there is .02
more moles of KNaO and a bit more silica than in the original formula. Just
add the usual amount of Iron.
regards, Craig Martell-Oregon
Untitled Recipe 1
CUSTER FELDSPAR 19.17 CaO 0.83*
WHITING 23.72 MgO 0.00*
EPK KAOLIN 28.84 K2O 0.08*
SODA FELDSPAR 8.08 Na2O 0.09*
SILICA 20.19 Fe2O3 0.00
======== TiO2 0.00
100.00 Al2O3 0.54
SiO2 3.05
Cost/kg 0.11
Si:Al 5.66
SiB:Al 5.66
Expan 7.15
Malone & Dean McRaine on thu 18 dec 97
Aloha,
Just an update. My glaze I'm trying to recover is a ^10. Many great ideas
and recalculations have come in, thanks to all. I had literally no-one on
Kauai that I could go to for help. Malone reminded me that I had fired pots
from the old batch of glaze with the load from the new batch that went wrong
and the old batch pots came out fine, ergo the firing/kiln is not the
problem. I'll be firing another round of tests within a week, I hope, and
I'll post results.
Merry Christmas to all
I love Clayart
Dean
DONPREY on mon 22 dec 97
HI Dean and other interested parties,
I told Dean that I would try to make and fire a sample of his nightmare glaze.
I did get that done and am posting to the group in case others can get some
value from the test. The testing went as follows:
I mixed a 200 gram batch of the following recipe:
Cornwall stone 50
EPK 25
Whiting 25
Red Iron Oxide 8
This was screened through an 80 mesh screen. At this point it was fairly
thick and I applied it to the first sample that way. Then I thinned it down
and did the second sample. Samples one and two were small pinch pots made
from an iron bearing, dark firing clay body (Pine Lake Red, Seattle Pottery
Supply). Glaze was applied to the inside only by pouring. A third sample was
prepared by dipping a shard from a broken mug....this gave a sample area about
3/4 x 3 inches on a vertical surface. The third sample was on a white,
porcelaineous stoneware (B-Mix, Laguna Clay Co.). As the kiln was being
loaded while I was preparing my samples, the glaze did not get any rest time
between mixing and application.
Firing was to cone 10 with fairly heavy reduction (the Pine Lake Red got
pretty toasted).
Results: 1. No movement of the glaze, even on the thicker application.
2. Surface is a nice satin matt. 3. Color on the Pine Lake Red is maroon
(thin) and near black (thick)...the thicker application shows some promise,
but I don't care much for the thin sample. 4. Color on the B-mix is the best
of the lot. Here it is an overall mahogany with black woven through and gives
a nice layerded appearance. The surface has a nice look and feel. I'll
probably use the rest of the sample batch on a B-mix vase in my January
firing.
Additional Info: The Cornwall Stone I used my have been around this
collective studio for anywhere between 5 and 15 years, it certainly isn't a
recent purchase. We have a high turnover rate on the other materials.
Dean, I don't see much help here for solving your problem, but at least I can
confirm that you wern't dreaming about all those times when the glaze worked
well for you. If this leaves any questions unanswered, please ask.
Happy Holidays
Don Prey in Oregon
Tony Hansen on thu 25 dec 97
I would not be too confident that the problem is not firing.
It is importat to identify the 'mechanism' of the color and
surface texture. As mentioned by others, the mechanism for
both the color and surface could be crstallization.
If it is then how stable is it? What changes will disrupt
proper development? Fluidity? Firing temperature? Cooling
rate? Once you identify (or even speculate) the mechanism
you can make changes that will cater to it, either by
adjusting firing, process, recipe or materials.
-
Tony Hansen thansen@digitalfire.com
Stephen Baird on thu 17 jun 99
I'm using ^5 Laguna glazes and having a heck of a time getting the stuff to
work for me. I'm hoping that some of you fine clayart folks can help me out.
Here is the problem specifically. I use a wax resist (waterbased and slow
drying) over a base glaze, and then dip the pot into a second glaze to reveal
the decoration. Many times the second glaze will peal away from the first at
room temperature. Most of the time however the glaze will wait until fired
to crawl and leave bare spots on the pot. I have tried thinning the glaze,
rubbing and smoothing the glaze before loading and firing, slow cooling the
kiln, etc. The problem has not gone away. Laguna says that the glaze is
either to thick, or that the first glaze is to dry when the second is
applied. I've used the same technique with other glazes at other
temperatures and never had close to this much trouble. Please, can anyone
suggest anything? Your input would be greatly appreciated.
Thank You in advance.
Stephen L. Baird
Bairdware Pottery
bairdware@aol.com
Lynne Antone on fri 18 jun 99
All of the below text is the same problem I have been fighting for the past
couple of years. All of my glazes are Laguna based and they have been very
helpful in trying to solve my problem, but no luck so far.
I've decanted over three times, each batch, and added rain water each time. I
have added Bentonite, I have gotten my Specific Gravity just so, bisque to 04
(glaze to 6), tried spraying the first coat to remoisten, do a soak after
cone 6 is reached and my second coats mostly peel (the base is usually a
white or clear glaze). I agree that thinning will help, but only if the
thinned glaze totally covers the previous glaze and does not stand alone, for
instance on the lower level of the pot, because then it's too thin to cover
the bisque well. I rub pots down where the glaze is not flaking off, and
about half the time, they also crawl away to reveal the clay body.
I am dying to know if there is any help for this problem, too. I have many
gallons of these glazes and can't just "get rid of them". Stephen, I totally
sympathize with you.
In a message dated 6/17/99 2:02:19 PM Pacific Daylight Time,
Bairdware@AOL.COM writes:
<< I'm using ^5 Laguna glazes and having a heck of a time getting the stuff to
work for me.....over a base glaze, and then dip the pot into a second glaze
to reveal
the decoration. Many times the second glaze will peal away from the first at
room temperature. Most of the time however the glaze will wait until fired
to crawl and leave bare spots on the pot. I have tried thinning the glaze,
rubbing and smoothing the glaze before loading and firing, slow cooling the
kiln, etc. The problem has not gone away. Laguna says that the glaze is
either to thick, or that the first glaze is to dry when the second is
applied. I've used the same technique with other glazes at other
temperatures and never had close to this much trouble..... >>
Antoinette Badenhorst on sat 19 jun 99
Stephen, I do not know much about Laguna glazes itself, but from
another potter I know, I learned that two layers of this glazez(in
particular the Moroccan sand glazes), can only be used successful if
the second is put on while the previous one is still almost wet. If I
can guess then I will say that you will have to change your wax resist
to a quicker drying one.
I do not know Gerstley borate, but from previous discussions on Clayart
I wonder if these glazes do not have a great amount of this raw
material in it. If that is true,then I guess one will have to
understand the nature of gerstley borate if you prefer these glazes.
Always learning,
Antoinette Badenhorst
--- Stephen Baird wrote:
> ----------------------------Original
> message----------------------------
> I'm using ^5 Laguna glazes and having a heck of a
> time getting the stuff to
> work for me. I'm hoping that some of you fine
> clayart folks can help me out.
> Here is the problem specifically. I use a wax
> resist (waterbased and slow
> drying) over a base glaze, and then dip the pot into
> a second glaze to reveal
> the decoration. Many times the second glaze will
> peal away from the first at
> room temperature. Most of the time however the
> glaze will wait until fired
> to crawl and leave bare spots on the pot. I have
> tried thinning the glaze,
> rubbing and smoothing the glaze before loading and
> firing, slow cooling the
> kiln, etc. The problem has not gone away. Laguna
> says that the glaze is
> either to thick, or that the first glaze is to dry
> when the second is
> applied. I've used the same technique with other
> glazes at other
> temperatures and never had close to this much
> trouble. Please, can anyone
> suggest anything? Your input would be greatly
> appreciated.
> Thank You in advance.
> Stephen L. Baird
> Bairdware Pottery
> bairdware@aol.com
>
===
Antoinette Badenhorst
PO Box 552
Saltillo,Mississippi
38866
Telephone (601) 869-1651
timakia@yahoo.com
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
joe & lisa cecere on mon 21 jun 99
Steve...I had this problem in the classroom/studio , I'm not a glaze
expert...but I switched to calcined kaolin instead of EPK. The glaze
behaved much better. Unfortunatly, you do not have the luxurary of making
small adjustments with commercial glazes. Maybe , adding more CMC (as most
commerical glazes already have put it in) to the glaze will hardened it on
better for the second coat.
Also, Laguna had a good suggestion, never let the first coat dry completly
before the second coat is added. You could also try drying the first coat
and then firing it to a very low cone (018) .....then wax and reglaze, then
fire to temp.
Good Luck...I'm sure others have lots of good suggestions
Lisa
-----Original Message-----
From: Stephen Baird
To: CLAYART@LSV.UKY.EDU
Date: Thursday, June 17, 1999 1:59 PM
Subject: glaze nightmare
>----------------------------Original message----------------------------
>I'm using ^5 Laguna glazes and having a heck of a time getting the stuff to
>work for me. I'm hoping that some of you fine clayart folks can help me
out.
>Here is the problem specifically. I use a wax resist (waterbased and slow
>drying) over a base glaze, and then dip the pot into a second glaze to
reveal
>the decoration. Many times the second glaze will peal away from the first
at
>room temperature. Most of the time however the glaze will wait until fired
>to crawl and leave bare spots on the pot. I have tried thinning the glaze,
>rubbing and smoothing the glaze before loading and firing, slow cooling the
>kiln, etc. The problem has not gone away. Laguna says that the glaze is
>either to thick, or that the first glaze is to dry when the second is
>applied. I've used the same technique with other glazes at other
>temperatures and never had close to this much trouble. Please, can anyone
>suggest anything? Your input would be greatly appreciated.
>Thank You in advance.
>Stephen L. Baird
>Bairdware Pottery
>bairdware@aol.com
>
Mike Bailey on mon 21 jun 99
In message , Stephen Baird writes
Dear Stephen,
Ref your glaze problem.
You do find that some glazes just don't double dip very well but there
are several things you can try.
1. Put a hardener into the first or both glazes. 2% approximate dry of
CMC usually works well. This can be sprinkled on to the slop glaze and
left over night to swell up. It can then be mixed into the glaze either
through vigorous stirring or passing the glaze through a coarse 30 or 40
mesh sieve.
2. Use a hot wax for the decoration. This dries instantly on the first
glaze and means that you can dip the second one straight away. It's a
bit more of a fiddle to set up. I use candle wax thinned with 50/50
paraffin and one has to have brushes dedicated to the process. Also take
care from the safety point of view. Another plus of this is that the
brush strokes can be thinner
Hope this helps,
Mike Bailey
>----------------------------Original message----------------------------
>I'm using ^5 Laguna glazes and having a heck of a time getting the stuff to
>work for me. I'm hoping that some of you fine clayart folks can help me out.
>Here is the problem specifically. I use a wax resist (waterbased and slow
>drying) over a base glaze, and then dip the pot into a second glaze to reveal
>the decoration. Many times the second glaze will peal away from the first at
>room temperature. Most of the time however the glaze will wait until fired
>to crawl and leave bare spots on the pot. I have tried thinning the glaze,
>rubbing and smoothing the glaze before loading and firing, slow cooling the
>kiln, etc. The problem has not gone away. Laguna says that the glaze is
>either to thick, or that the first glaze is to dry when the second is
>applied. I've used the same technique with other glazes at other
>temperatures and never had close to this much trouble. Please, can anyone
>suggest anything? Your input would be greatly appreciated.
>
--
Mike Bailey
Lis Allison on tue 4 may 10
I seem to be trapped in a glaze nightmare..... one of the things several
people (not all on this list) suggested was adding epsom salts to keep it
suspended. Like a fool, I mixed some up and added what I thought was a wee
bit to a large tub of glaze, and watched as it turned to cottage cheese.
Dark red-brown cottage cheese. Dark red-brown cottage cheese that I will
never in a million years be able to get to evenly cover my pots.
Does anyone know a cure for this? Is there a way out of this
nightmare..... do I deserve a way out after this idiocy??><#@#!???...don't
answer that, please..... just send help!
Lis
--
Elisabeth Allison
Pine Ridge Studio
www.Pine-Ridge-Studio.blogspot.com
Edouard Bastarache on tue 4 may 10
When you wash some wood ash, you get rid of solubles.
Since Epsom salt is water-soluble, you can wash your
glaze a few times, as in the case of ash, and get rid of it.
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://blogsalbertbastarache.blogspot.com/
http://cerampeintures.blogspot.com/
http://perso.wanadoo.fr/smart2000/index.htm
----- Original Message -----
From: "Lis Allison"
To:
Sent: Tuesday, May 04, 2010 12:24 PM
Subject: Glaze Nightmare
>I seem to be trapped in a glaze nightmare..... one of the things several
> people (not all on this list) suggested was adding epsom salts to keep it
> suspended. Like a fool, I mixed some up and added what I thought was a we=
e
> bit to a large tub of glaze, and watched as it turned to cottage cheese.
> Dark red-brown cottage cheese. Dark red-brown cottage cheese that I will
> never in a million years be able to get to evenly cover my pots.
>
> Does anyone know a cure for this? Is there a way out of this
> nightmare..... do I deserve a way out after this idiocy??><#@#!???...don'=
t
> answer that, please..... just send help!
>
> Lis
>
>
> --
> Elisabeth Allison
> Pine Ridge Studio
> www.Pine-Ridge-Studio.blogspot.com
>
David Finkelnburg on wed 5 may 10
Liz,
First, I am sorry to hear about this. I have done the same sort of
thing with too much bentonite, too much CMC, ...it's how I find the limits!
There is a quicker solution, of course, but that is to dump the offendin=
g
glaze and just move on. If you want to make the effort...try taking a cup
of the glaze and putting it in a quart container with three cups of water,
mix very well, then leave it sit and see if it will settle out. Give it at
least 48 hours to do this, possibly a week. If it hasn't settled out in a
week it needs even more dilution.
Once the glaze settles, pour or siphon off the water. Since the Epsom
salt is dissolved, if you can take off ~3 cups of water you will have
removed ~75% of the Epsom salts. If your test works, scale up to the whole
batch.
In the future, may I suggest weighing the Epsom salts at a rate of not
more than 0.7% (less than a gram per 100 grams of dry glaze). I usually
start with ~0.35% Epsom salt when I see I need some. Better is to reduce
the water in the glaze first, by letting it sit and decanting it or else
making up a batch with less water--higher density. Any glaze will suspend
better as the density increases. For glazes with 10% clay in the recipe I
try for a density around 1.5 grams/cc, as clay % rises or other suspension
aids are used, density can drop to a minimum, for me, of ~1.4. This is for
dipping porous bisque.
Addition of clay or bentonite or a veegum type material to the recipe i=
s
my next choice after removing water. Just be careful to hydrate bentonite
so it doesn't clump.
Adding Epsom salt or CMC is my last choice. They are fine if you use
the glaze quickly but they "age" and suspension effect changes over time in
a stored glaze.
Good potting,
Dave Finkelnburg
-----------------------------
On: Tue, 4 May 2010 12:24:23 -0400
Lis Allison wrote:
I seem to be trapped in a glaze nightmare..... one of the things...suggeste=
d
was adding epsom salts to keep it suspended. Like a fool, I mixed some up
and added what I thought was a wee
bit to a large tub of glaze, and watched as it turned to cottage cheese.
Does anyone know a cure for this?
Lis Allison on fri 7 may 10
Just a quick note to all those who so kindly replied to my frantic request
for help, especially John Britt: Thank you, and yes, it worked.
To re-cap, I mixed a batch which sank like a rock and was impossible to
use, and tried epsom salts to suspend it and created cottage cheese, and
John suggested I add sodium silicate, drop by drop, to turn it back to
liquid, and that worked. Whew. I mix my production glazes in large batches
(32,000 grams) so not only did I not have a batch to dip pots I needed for
my Market opening tomorrow, but also I was looking at a big waste, a
disposal problem, and a serious shortage of large-enough containers!
Thanks for all the help - you guys are the best!
Lis
--
Elisabeth Allison
Pine Ridge Studio
www.Pine-Ridge-Studio.blogspot.com
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