Robert L. Dunn on fri 13 feb 98
Hi everyone, This is my first request for help. I have been working
on layering glazes and developed three that blend together sometimes.
What I find is that I can,t seem to get any consistancy. Sometimes I
get crawling and or pitting. I use a blue, a green and a burgundy
combo. I dip, pour, paint or spray my glazes trying to find the best
way to do it. Does anyone have any info on layering glazes and or any
glaze recipies that work well together. I use a cone 6 buff clay with a
manganese speckle. I would appreciate any help. Thankyou. Lynn
douglas gray on sat 14 feb 98
In message "Robert L. Dunn" writes:
> ----------------------------Original message----------------------------
> Hi everyone, This is my first request for help. I have been working
> on layering glazes and developed three that blend together sometimes.
> What I find is that I can,t seem to get any consistancy. Sometimes I
> get crawling and or pitting. I use a blue, a green and a burgundy
> combo. I dip, pour, paint or spray my glazes trying to find the best
> way to do it. Does anyone have any info on layering glazes and or any
> glaze recipies that work well together. I use a cone 6 buff clay with a
It could be a couple of things.
1. You might be using glazes that are not really compatable. Some glazes just
don't mix well. The best mixes come from variation of the same base glaze. If
you are using comercial glazes and they are all the same brand, they should mix
fine. If you mix your own glazes, compare recipes and see what they have in
common. It is possible, to take a blue glaze, remove the cobalt and add copper
or chrome to get a green, or add mason stains to get a burgundy-all three
variation with one base. This will, of course, require some testing to get the
right amounts of colorant.
2. You might find that the layering works well in a specific order. For
instance we have a shino glaze in the lab that mixes well with other glazes
provided it is applied first with the other glazes applied over it. If you
reverse the order you get a lot of crawling. So look at the pieces that worked,
try to determine the layering order, and compare that with the order on the
pieces that didn't work. See if there is common order that works and stick to
it.
3. The other factor is the amount of time between the application of layers.
Do you pour the glaze, do you glaze all in one day, or do you apply one color,
wait a day or two and the the next, wait a day ot two, and then the third? The
longer the time span between layers, the more problems you are likely to have.
Dust and other particles could be settling onto the work between application
causing an unsuccessfyl bond between the glazes in the dry state which could
lead to problems in the fired state. Also the water from the second or third
application of glaze can soak through the first layer, actually weakening it's
attachment to the clay. It's best to apply layered glazes quickly, with only
minimal drying time between each coat.
Hope this makes some sense. Typing faster than I'm thinking, I'm afraid.
doug
============================================================================ =)
Douglas E. Gray, Assistant Professor of Art
P.O. Box 100547
Department of Fine Arts and Mass Communication
Francis Marion Univeristy
Florence, South Carolina 29501-0547
dgray@fmarion.edu
803/661-1535
"Robert L. Dunn (by way of the cat lady on sun 15 feb 98
----------------------------Original message----------------------------
Hi everyone, This is my first request for help. I have been working
on layering glazes and developed three that blend together sometimes.
What I find is that I can,t seem to get any consistancy. Sometimes I
get crawling and or pitting. I use a blue, a green and a burgundy
combo. I dip, pour, paint or spray my glazes trying to find the best
way to do it. Does anyone have any info on layering glazes and or any
glaze recipies that work well together. I use a cone 6 buff clay with a
manganese speckle. I would appreciate any help. Thankyou. Lynn
Hi Lynn:
Quite a lot of my work is layered - visit my homepage, go to
"Maid O'Mud" link and look at the cream/sugar. I have other
overlaps as well.
I dip all my glazes. May I suggest the following.
- Use your lighter colour 1st
- thin your 2nd colour
- let 1st colour dry til easily handled, but not bone dry
- all my glazes are at a thickness that allows "quick" dips;
in and out, no counting. I would imagine this is one of
the secrets to my success
- finally, rub lightly on the overlap when completely dry
As I work in ^10, none of my recipes can help you. Hope the
above offers some insight.
sam - alias the cat lady
Melbourne, Ontario
SW Ontario CANADA
http://www.geocities.com/paris/3110
the cat lady on mon 16 feb 98
----------------------------Original message----------------------------
Hi everyone, This is my first request for help. I have been working
on layering glazes and developed three that blend together sometimes.
What I find is that I can,t seem to get any consistancy. Sometimes I
get crawling and or pitting. I use a blue, a green and a burgundy
combo. I dip, pour, paint or spray my glazes trying to find the best
way to do it. Does anyone have any info on layering glazes and or any
glaze recipies that work well together. I use a cone 6 buff clay with a
manganese speckle. I would appreciate any help. Thankyou. Lynn
Hi Lynn:
Quite a lot of my work is layered - visit my homepage, go to
"Maid O'Mud" link and look at the cream/sugar. I have other
overlaps as well.
I dip all my glazes. May I suggest the following.
- Use your lighter colour 1st
- thin your 2nd colour
- let 1st colour dry til easily handled, but not bone dry
- all my glazes are at a thickness that allows "quick" dips;
in and out, no counting. I would imagine this is one of
the secrets to my success
- finally, rub lightly on the overlap when completely dry
As I work in ^10, none of my recipes can help you. Hope the
above offers some insight.
sam - alias the cat lady
Melbourne, Ontario
SW Ontario CANADA
http://www.geocities.com/paris/3110
rballou@mnsinc.com on mon 16 feb 98
Here are a few tips I gathered from David and Margaret Frith at Aberystwyth
last summer. They apply multiple layers of glaze with impunity, allowing
the glaze to dry between the layers while they apply wax resist.
1) Mix the glazes very thin, consistency of milk or less.
2)Bisque low -- ^010. A higher bisque will not absorb enough of the thinned
glaze, though a higher bisque/thicker glaze may work if you're doing just 2
layers. The Friths casually pour glaze over the surface of large platters.
If a spot is missed, they can go back over it with more glaze without
worrying about too thick of a glaze coat.
3)If you're still having problems, try calcining part or most of the clay
in the glaze. This will help if the glaze is crawling due to excessive
shrinkage as it dries. You can also try substituting lower shrinkage clays
for higher shrinkage clays. This is what finally solved a crawling problem
I had with two glazes, even though there was only about 10% clay in each of
them.
Ruth Ballou
>----------------------------Original message----------------------------
>Hi everyone, This is my first request for help. I have been working
>on layering glazes and developed three that blend together sometimes.
>What I find is that I can,t seem to get any consistancy. Sometimes I
>get crawling and or pitting. I use a blue, a green and a burgundy
>combo. I dip, pour, paint or spray my glazes trying to find the best
>way to do it. Does anyone have any info on layering glazes and or any
>glaze recipies that work well together. I use a cone 6 buff clay with a
>manganese speckle. I would appreciate any help. Thankyou. Lynn
the Gallagher's on fri 2 oct 98
I have a question that someone out there might be able to help me with.
When layering glazes in subsequent firing, do I need to be concerned about the
glazes running off of the piece? I still fire at school, so I don't want to
try this if it will cause problems.
I just found an old issue of Ceramics Monthly with an article on the Belgian
artist Carmen Dionyse. She mutifires her pieces that are layered in slips and
glazes.
The surfaces are crackled and chunky looking, but perfect for sculptural
forms.
Has anyone on the list gotten into multifiring??
I know that each firing goes to a lower temperature, so I assume that the
glazes must fit the temperature of the firing. This would mean to me that the
first firing of the hotter temp glazes would not be in danger of running off.
Is this correct??
Is there a book that gets into this process??
Michelle
In Oregon
Cindy on sat 3 oct 98
Michelle,
Glazes are *always* in danger of dripping on kiln shelves--'specially until
you learn how thick to apply them. If you are in doubt, set your piece on a
bisqued slab/plate/whatever. Lower fire glazes have far less of a tendency
to run than higher temp glazes.
Cindy Strnad
Earthen Vessels
Custer, SD
USA http://blackhills-info.com/a/cindys/menu.htm
----------
> From: the Gallagher's
> To: CLAYART@LSV.UKY.EDU
> Subject: Layering Glazes
> Date: Friday, October 02, 1998 11:33 AM
>
> ----------------------------Original message----------------------------
> I have a question that someone out there might be able to help me with.
>
> When layering glazes in subsequent firing, do I need to be concerned
about the
> glazes running off of the piece? I still fire at school, so I don't want
to
> try this if it will cause problems.
>
> I just found an old issue of Ceramics Monthly with an article on the
Belgian
> artist Carmen Dionyse. She mutifires her pieces that are layered in
slips and
> glazes.
> The surfaces are crackled and chunky looking, but perfect for sculptural
> forms.
>
> Has anyone on the list gotten into multifiring??
> I know that each firing goes to a lower temperature, so I assume that the
> glazes must fit the temperature of the firing. This would mean to me
that the
> first firing of the hotter temp glazes would not be in danger of running
off.
> Is this correct??
>
> Is there a book that gets into this process??
>
> Michelle
> In Oregon
>
Earl Brunner on sat 3 oct 98
We don't multiple fire much, but the students "newbies" at the art center like
the effects they see from overlapping glazes. It is one of the easiest early
ways to "decorate", they aren't always successful by my standards but they
frequently are quite happy by theirs. As they mature as potters so will there
glazing. I don't mean to imply that overlapping is a bad way to glaze, I was
just digressing a bit. My experience is that overlapped glazes do tend to run
more than either one of the glazes by themselves, so you do need to be
careful, which is more to the point of your question. Since they like to do
it, I've had a lot of experience cleaning the shelves. I have come up with a
couple of general rules for the studio. No overlapping glazes on the bottom
third of the pot. From experience, some studio glazes are posted as not
allowed combinations. Applications is critical, total combined time in both
glazes should not (difficult to do) exceed total time for one glaze when
dipping. Run some tests!
Earl Brunner in Las Vegas - TGIF!!!
David & Diane Chen on sat 7 aug 99
-------------------
Okay, time for another obvious (?) stupid question. I work mostly with
transparent glazes, but have been wanting to try layering glazes. I've read=
the
archives, but in looking at some examples, seems most of the glaze layering
involves matte/opaque glazes. Is this true? Will I just need to add some
opacifier to my transparent glazes to try layering?
Diane
Massachusetts
Craig Martell on sun 8 aug 99
Hi:
>seems most of the glaze layering involves matte/opaque glazes. Is >this
true? Will I just need to add some opacifier to my transparent >glazes to
try layering?
I don't think you need to add anything unless you want to. All kinds of
glazes are layered and it doesn't matter if they are transparent or opaque
or matt or what. The thing to do is try layering what you have and are
using. Alternate what goes under and over other glazes and exhaust all the
possibilities that you have. See what happens. You may then want to do
some opacifying and other changes.
The only things I know about are to do the layering and reapplying before
the glazes dry out and be aware that there will be a greater chance of the
glaze lifting if you apply a higher clay content glaze over one that has a
lower percentage of clay. You can calcine some of the clay in the glaze to
avoid this but I wouldn't do any calcining unless there is a definite need
to do it.
hope you get some good results, Craig Martell in Oregon
Nanci Bishof on mon 9 aug 99
Layering of transparent glazes works beautifully with glazes that don't react
to make a drip disaster. Its like layering sheets of glass or paint glazes to
create new hues & subtleties.
Test before doing on your pieces. Much better to loose test tiles than work.
nanci
Abbey of New Clairvaux on mon 9 aug 99
Dear Diane,
I'm not sure what you mean by layering glazes, but I dip a pot in one glaze,
wait a few minutes till the glaze surface is dry and dip it into another
glaze. Sometimes I dip it into a third glaze. I have to wait a lot longer
for the second glaze to dry. By dry, I don't mean that the moisture
absorbed by the pot is dry, just the surface of the glaze seems dry.
With two glazes, you get one effect by dipping into A glaze and then in B
glaze, and another effect if you dip into B glaze and then into A glaze. So
with 2 glazes you can get 4 effects. It makes no difference if the glaze is
matte or glossy. I'm not sure why you would want to do this with a
transparent glaze, unless that would effect the second glaze, which I
suppose it would. In the end, it all comes down to testing to see what you
get when you do this and that. Personally, I find this a very fun thing to
do.
I hope this might be helpful. Fr. Anthony
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
Of David & Diane Chen
Sent: Saturday, August 07, 1999 11:34 AM
To: CLAYART@LSV.UKY.EDU
Subject: layering glazes
----------------------------Original message----------------------------
-------------------
Okay, time for another obvious (?) stupid question. I work mostly with
transparent glazes, but have been wanting to try layering glazes. I've read
the
archives, but in looking at some examples, seems most of the glaze layering
involves matte/opaque glazes. Is this true? Will I just need to add some
opacifier to my transparent glazes to try layering?
Diane
Massachusetts
Susan Goldstein on tue 10 aug 99
No, you can layer any glazes, getting a third color and interesting effects .
However I sometimes get unattractive bubbles or craters when mixing a matt
with a gloss. Keep in mind that the combination of the glazes greatly
increases the fluxing action and the glazes can become excessively runny.
Susan
Karen Sullivan on sat 28 oct 00
Take a look at Rimas Visgirda's work..
He starts with cone 10, then does multiple layers and fires down with each
layer...He uses a lot of lusters as well.
You can see his work on Guild.com, in addition to several books and
publications.
bamboo karen
Marianne Lombardo on wed 22 aug 01
A couple of times I have reglazed an already glazed and fired pot, and =
fired again because I didn't really care for the first result. I've =
discovered that putting the 20 x 5 with 12 Tin oxide can perform wonders =
over top of some matte glazes, if two separate firings are done. And =
with a 30 minute soak and very slow cool to 1900F.
However, if I try to duplicate the effect by putting glaze one on the =
bisqued pot and letting it dry, then applying glaze two and glaze firing =
only the once, I get entirely different results. (all firings at ^6)=20
I don't understand that because shouldn't the glazes melt the same, =
regardless?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
Dannon Rhudy on wed 22 aug 01
Marianne said:
.....>I have reglazed an already glazed and fired pot, ....
if I try to duplicate the effect by putting glaze one on the bisqued pot
...then applying glaze two and glaze firing.... I get entirely different
results...... shouldn't the glazes melt the same, regardless?.....
Indeed, as you have observed, they do NOT melt the same on second
firing. Some glazes tend to melt about one cone lower on second firing.
So your initial glaze will fire differently than your second one.
Your own observations will teach you a lot regarding your own
glazes. Keep notes. All glazes will not behave the same - some
over fire/blister upon second firings. If you keep good records
you will know more or less what to expect - an adventure.
regards
Dannon Rhudy
Ababi on wed 22 aug 01
Enter to http://members.bellatlantic.net/~spilacho/ You can learn a lot.
Look for Stephen Pilachowski's letters to clayart last year.
In my humble knowledge, when you use a high alumina glaze above a lower
alumina glaze it behaves like a chocolate bare, melting into boiled water.
( can see in my site, humble too)
I did not give much attention to layering glazes, but should be different
between one firing(as I usually do and second firing. You may try Lana
Wilson's dry engob, as an in-between, in case that your first glaze fails.
You must be aware that it might cause kind of lizard skin.
I don't find the book, so buy (you will not regret) it or ask someone. I add
cmc as glue and apply twice.
Ababi Sharon
ababisharon@hotmail.com
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
----- Original Message -----
From: "Marianne Lombardo"
To:
Sent: Wednesday, August 22, 2001 06:42
Subject: Layering Glazes
A couple of times I have reglazed an already glazed and fired pot, and fired
again because I didn't really care for the first result. I've discovered
that putting the 20 x 5 with 12 Tin oxide can perform wonders over top of
some matte glazes, if two separate firings are done. And with a 30 minute
soak and very slow cool to 1900F.
However, if I try to duplicate the effect by putting glaze one on the
bisqued pot and letting it dry, then applying glaze two and glaze firing
only the once, I get entirely different results. (all firings at ^6)
I don't understand that because shouldn't the glazes melt the same,
regardless?
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
____________________________________________________________________________
__
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.
C TRIPP on wed 22 aug 01
Hi Marianne,
I can't answer your question but I can tell you that when I refire a pot
without adding any fresh glaze to the single or double layer of already
glazed area it will come out looking different after the second firing;
usually mellower. I have a few glazes that look better when double fired to
the same cone.
FYI, I have refired a 5x20 that has tin and copper carb. (It needed a dab
of glaze to cover a single bit of crawling.) It came out with a subtle
varigated effect.
Why? I suppose it is the extra heatwork. But I'm only guessing.
Regards, Carol
On Wed, 22 Aug 2001 00:42:02 -0400, Ceramic Arts Discussion List wrote:
Marianne wrote:
> A couple of times I have reglazed an already glazed and fired pot, and
fired again because I didn't really care for the first result...
>...However, if I try to duplicate the effect by putting glaze one on the
bisqued pot and letting it dry, then applying glaze two and glaze firing
only the once, I get entirely different results. (all firings at ^6)
> I don't understand that because shouldn't the glazes melt the same,
regardless?
>
_______________________________________________________
Send a cool gift with your E-Card
http://www.bluemountain.com/giftcenter/
Earl Brunner on wed 22 aug 01
This is just a guess on my part, but as I understand glaze melt
sometimes you get a significant amount of outgassing during the melt of
the glaze. That is, there are materials in some of the glaze materials
that we use that are there before firing, but either not there after
firing or are there but in a smaller quantity. Some of the glazes that
we use in the city lab here at cone 6 will leave a ring of glaze
coloring around the fired pot on the kilnwashed shelf. To do that,
there has to be a fair amount of activity going on in the glaze during
the firing.
I would surmise that during a second firing you might get less of this
activity. SO, if you have two glazes layered and being fired in a
single firing, as they both will get more active than say glazes that
are being refired and consequently less active, then you will bet more
mixing of the two, so that the results will be different.
When you add a second glaze and refire, you may have the dynamics of
less activity happening in the refired glaze plus the fact that you may
have a thinner coat of the second glaze (its harder to get a thicker
glaze coat on a non-porous surface).
Marianne Lombardo wrote:
> A couple of times I have reglazed an already glazed and fired pot, and fired again because I didn't really care for the first result. I've discovered that putting the 20 x 5 with 12 Tin oxide can perform wonders over top of some matte glazes, if two separate firings are done. And with a 30 minute soak and very slow cool to 1900F.
>
> However, if I try to duplicate the effect by putting glaze one on the bisqued pot and letting it dry, then applying glaze two and glaze firing only the once, I get entirely different results. (all firings at ^6)
>
> I don't understand that because shouldn't the glazes melt the same, regardless?
>
> Marianne Lombardo
> Omemee, Ontario, Canada
> email: mlombardo@nexicom.net
>
> ______________________________________________________________________________
> 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
Veena Raghavan on wed 22 aug 01
Has anyone found that their glazes tend to pinhole on the second firing,
usually on the outside? Thanks in advance for any replies ot this.
Veena
Veena Raghavan
75124.2520@compuserve.com
Paul Lewing on wed 22 aug 01
on 8/22/01 4:42 AM, Marianne Lombardo at mlombardo@NEXICOM.NET wrote:
> However, if I try to duplicate the effect by putting glaze one on the =
> bisqued pot and letting it dry, then applying glaze two and glaze firing =
> only the once, I get entirely different results. (all firings at ^6)=20
>
> I don't understand that because shouldn't the glazes melt the same, =
> regardless?
No. Two things have changed.
For one thing, you have essentially fritted the first glaze by firing it
once. So it will now take less heat to make it melt again.
Second, the first glaze no longer has any loss on ignition, as all that
stuff got burned off in the first firing. So a lot of the textural effects
you would normally get by layering glazes will not occur. That stuff is
often caused by gas bubbles boiling through the top molten glaze from the
bottom one.
Paul Lewing, Seattle
Gail Dapogny on thu 23 aug 01
Hi Veena,
I've found that if I refire because of just one pinhole, then most often
the refiring takes care of the problem, But if I reglaze and refire because
of multiple pinholes, the old ones may seal over, but new ones almost
always show up, usually in greater numbers. Very frustrating. These are
the ones that make me wonder about the clay content rather than the glaze
or firing.
Otherwise, I've sometimes had pinholes just show up in the refiring as you
describe. Recently Dannon mentioned that some glazes melt a cone sooner
in refiring, making me wonder if refiring such glazes promotes blistering
or the beginning of blistering due to overfiring.
I'll be very interested in hearing the replies that come in.
---Gail
>Has anyone found that their glazes tend to pinhole on the second firing,
>usually on the outside? Thanks in advance for any replies ot this.
>
>Veena
Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
Cindi Anderson on sat 14 feb 04
Can anybody explain why layering glazes often gives variegated effects, like
the top coat is sliding down the base coat?
I know this is probably a basic question but I haven't come across the
answer. If the top coat were always a glaze that melted a lot on its own, I
would understand. But usually neither the top or the bottom coats are runny
by themselves. Yet together they run.
Are there certain characteristics that you want in the base or top coats for
this to happen (high silica for example)?
(If you want to refer me to a book, that is fine. I have most of them.)
Thanks
Cindi
Fremont, CA
David Hendley on sun 15 feb 04
This is another example of why it is worthwhile to know
glaze chemistry on the molecular level, rather than just
mixing and using glazes from glaze recipes.
For the best variegated effects, the two glazes should be
very different. The most pronounced effects seem to come
from a combination of one glaze with a low alumina/silica
ratio and one with a high ratio.
Glazes with very similar formulae will just kind of melt
and blend together.
You can readily compare glazes and have a good idea
as to which ones will work well together by looking at
their unity formulae.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
>
>Can anybody explain why layering glazes often gives variegated effects,
> like the top coat is sliding down the base coat?
>
Paul Lewing on sun 15 feb 04
on 2/14/04 1:33 PM, Cindi Anderson at cindi@CINDI-ANDERSON.COM wrote:
> Can anybody explain why layering glazes often gives variegated effects, like
> the top coat is sliding down the base coat?
>
> I know this is probably a basic question but I haven't come across the
> answer. If the top coat were always a glaze that melted a lot on its own, I
> would understand. But usually neither the top or the bottom coats are runny
> by themselves. Yet together they run.
>
> Are there certain characteristics that you want in the base or top coats for
> this to happen (high silica for example)?
It's a basic question, but not a simple one to answer. A lot of it has to
do with a principle called eutectics, which basically says that the
combination of any two fluxes melts at a lower temperature than either one
separately. So you'll often notice that if you put two different color
variations of the same base over each other, you get very little of this
"action". The more different the two glazes are from each other, the more
they interact. You will also see that if one has a high alumina-to-silica
ratio, and the other a low ratio, you will get more interaction. One other
thing that affects the patterns you get is the amount of outgassing the two
glazes do. For instance, say you're layering a copper red and a temmoku in
reduction. The temmoku will bubble and boil a lot more than the copper red,
because there's so much iron being reduced. So if the temmoku is
underneath, you'll get a more broken-up pattern than if you layer them the
other way.
But there is never any way to predict what will happen exactly when you
layer glazes. It's too dependent on too many variables- relative thickness,
the order they're applied, how much reduction or oxidation, the temperature,
the firing cycle, the pitch of the wall they're on, the chemistry of the two
glazes, and so on. You just have to do it and see what you get.
Paul Lewing, Seattle
william schran on sun 15 feb 04
Cindi wrote:>Can anybody explain why layering glazes often gives
variegated effects, like
the top coat is sliding down the base coat?<
I was told years ago that a glaze is a combination of
materials/chemicals that when heated form a eutectic (the materials
acting together to melt at a lower temperature than they would
individually or a temperature than they would be expected to melt
at). If one layers two glazes, another, more complicated eutectic is
created, thus melting at a temperature lower than would each of the
glazes individually.
Bill
sdr on sun 15 feb 04
Cindi asked:
> Can anybody explain why layering glazes often gives variegated effects,
like
> the top coat is sliding down the base coat?
Because the top coat probably IS sliding down the base coat.
It depends very much upon the glazes you are using (isn't it
tiresome to keep hearing that?). Often, if one layers a gloss
glaze over a matt glaze, the gloss will appear to slide and
drip a bit. If a matt is used over a gloss, then variety of
surface might be more pronounced - sometimes unexpected
colors, streaks, a "hare's fur" effect might be noted. Much
depends upon the contents of each glaze, and the effect
various ingredients may have upon one another.
It is necessary to test each combination of glazes, in various
orders and thicknesses of application, to find what your glaze
palette is capable of. One might make an educated guess
about results if one has experience, but even then it could be
wrong. If you are using commercial glazes, test, test, test.
If you're making your own, test some more, and check it out
on a glaze program if you have one, since you'll know what
the ingredients are.
regards
Dannon Rhudy
Cindi Anderson on sun 15 feb 04
> Because the top coat probably IS sliding down the base coat...Often, if
one layers a gloss glaze over a matt glaze, the gloss will appear to slide
and drip a bit. If a matt is used over a gloss, then variety of surface
might be more pronounced - sometimes unexpected colors, streaks, a "hare's
fur" effect might be noted
But why?
> If you're making your own, test some more, and check it out
> on a glaze program if you have one, since you'll know what
> the ingredients are.
Again, I am not tring to make this happen. I am trying to understand the
chemistry of why it happens. Testing will not help me with that.
Thanks
Cindi
L. P. Skeen on sun 15 feb 04
Cindi,
Woo hoo, I know this one!!! :)
Individual glazes are designed to melt at a certain temperature. This
varies from glaze to glaze, even at one given temperature - some can take a
"hotter" cone six, some take a "cooler" cone six, and so on. When you blend
two glazes (overlap), the eutectic changes, and they melt differently
together than they would if each glaze was left on its own. Also, your
colorant choices can have a great deal to do with this, as some of them are
earlier melters than others.
L
----- Original Message -----
From: "Cindi Anderson"
> Can anybody explain why layering glazes often gives variegated effects,
like
> the top coat is sliding down the base coat?
Tony Hansen on sun 15 feb 04
Check this page:
http://digitalfire.ab.ca/cermat/education/25.html
-------8<--------
Can anybody explain why layering glazes often gives variegated effects, like
the top coat is sliding down the base coat?
I know this is probably a basic question but I haven\'t come across the
answer. If the top coat were always a glaze that melted a lot on its own, I
would understand. But usually neither the top or the bottom coats are runny
by themselves. Yet together they run.
Are there certain characteristics that you want in the base or top coats for
this to happen (high silica for example)?
-------
Tony Hansen, http://digitalfire.com
Personal Contact Page: http://208.55.130.23/services/contact.php
Calculation/Database Software for Ceramic Industry
Ababi Sharon on mon 16 feb 04
Hello Cindi
Please visit
http://members4.clubphoto.com/ababi306910/912566/
and
http://members.bellatlantic.net/~spilacho/index.htm
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
To Ceramics forum in Hebrew:
http://www.botzpottery.co.il/kishurim.html
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of L. P. Skeen
Sent: Sunday, February 15, 2004 6:12 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Layering glazes
Cindi,
Woo hoo, I know this one!!! :)
Individual glazes are designed to melt at a certain temperature. This
varies from glaze to glaze, even at one given temperature - some can
take a
"hotter" cone six, some take a "cooler" cone six, and so on. When you
blend
two glazes (overlap), the eutectic changes, and they melt differently
together than they would if each glaze was left on its own. Also, your
colorant choices can have a great deal to do with this, as some of them
are
earlier melters than others.
L
----- Original Message -----
From: "Cindi Anderson"
> Can anybody explain why layering glazes often gives variegated
effects,
like
> the top coat is sliding down the base coat?
________________________________________________________________________
______
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.
Ivor and Olive Lewis on mon 16 feb 04
Dear Cindi Anderson,
In a general way this is a question which can only be answered if you
have a lot of knowledge about the glazes concerned and the knowledge
needed is not readily available to the potting community as values in
the same way as those for Coefficients of Expansion.
You are observing the viscous behaviour of a molten silicate, the
degree to which it will flow or resist the forces which make it flow..
Although several glazes may mature and fully fuse at identical
temperatures their chemistry controls their individual flow
characteristics.
If you can get hold of Hamer, F., "The Potter's Dictionary of
Materials and Techniques" then read and digest the section on
"Viscosity".
Once you understand his principles you can estimate the degree to
which any of your glazes will flow by comparing Seger oxide
proportions of each oxide in your glazes according to its position in
the table and the volume in each glaze.
I suggest you do some trials, make observations and make some
comparisons with Hamers tables. This may give you sufficient knowledge
to build up an empirical weighting for each of the oxides.
Best regards,
Ivor Lewis. Redhill, South Australia
----- Original Message -----
From: "Cindi Anderson"
To:
Sent: Sunday, 15 February 2004 8:03
Subject: Layering glazes
> Can anybody explain why layering glazes often gives variegated
effects, like
> the top coat is sliding down the base coat?
>
> I know this is probably a basic question but I haven't come across
the
> answer. If the top coat were always a glaze that melted a lot on
its own, I
> would understand. But usually neither the top or the bottom coats
are runny
> by themselves. Yet together they run.
>
> Are there certain characteristics that you want in the base or top
coats for
> this to happen (high silica for example)?
>
> (If you want to refer me to a book, that is fine. I have most of
them.)
>
> Thanks
> Cindi
> Fremont, CA
>
>
______________________________________________________________________
________
> 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.
Lee Love on mon 16 feb 04
Tony Hansen wrote:
>Check this page:
>http://digitalfire.ab.ca/cermat/education/25.html
>
>
>quote from this link:
>
Multilayering
> Double layering of different glazes produces variegation well when the
> lower layer is more fluid. The upper, stiffer glaze tends to break
> into islands revealing rivulets of the lower one. Similarly, a
> contrasting colored fluid glaze over a stable one often has its own
> variegation surprises. However be aware of the problems associated
> with double layer glazing (cracking and crawling during drying because
> either layer shrinks too much, is applied too thick, or onto wet
> ware). Use glazes with lower or less plastic clay content for
> multilayer work or bisque the first layer on.
>
The other cause is when the bottom layer is "active" and
releasing gases during the melt. This can be seen in ash glazes used
over albany/alberta slip glazes. Even though the top layer is more
fluid than the bottom, the albany will percolate and leave craters in
the layer above it. Later, as the melt progresses, these craters
heal, mixed with the layer above.
Lee In Mashiko http://mashiko.us
Cindi Anderson on mon 16 feb 04
Thanks to everyone for responding, especially David and Paul for your
molecular explanations.
I fully understand that we cannot predict what is going to happen with a
glaze without testing. But as an engineer (or maybe this is why I became an
engineer), I can't deal with things if I don't at least have a concept of
why they are happening. I don't enjoy just guessing and testing; I have to
understand chemically what is going on, then I can interpret results and and
make educated guesses for my next move. I couldn't even deal with baking
until I learned what the different ingredients did: what an egg does, what
baking soda does, what salt does, etc. (Of course I never could find good
answers to all the ingredients of cooking and maybe that's why I still hate
to cook!)
Cindi
Ivor and Olive Lewis on tue 17 feb 04
Dear William Schran,
If what we are told about Eutectics were true, every one of our glazes
would melt in the region of 700=BAC ~1300=BAF if they contained oxides of
Sodium, Potassium, Silicon and Aluminium.
Best regards,
Paul Lewing on tue 17 feb 04
on 2/16/04 11:51 AM, Cindi Anderson at cindi@CINDI-ANDERSON.COM wrote:
> I fully understand that we cannot predict what is going to happen with a
> glaze without testing. But as an engineer (or maybe this is why I became an
> engineer), I can't deal with things if I don't at least have a concept of
> why they are happening. I don't enjoy just guessing and testing; I have to
> understand chemically what is going on, then I can interpret results and and
> make educated guesses for my next move. I couldn't even deal with baking
> until I learned what the different ingredients did: what an egg does, what
> baking soda does, what salt does, etc.
Ah, Cindi, a right-brain thinker all the way! One of my thesis committee, a
geology professor specializing in clay mineralogy was the same way. He was
offended by the very idea of a scrap glaze. We kept telling him it came out
the same all the time, and we liked how it looked, and that that was all
that was important. He didn't see how you could use something you couldn't
reproduce.
One of the very best things about ceramics is that it's a blend of art and
science. And everyone picks where on the continuum from art to science they
like to hang out. Nobody who does it successfully is at either end of the
spectrum. The best are always some blend of the two.
I often make the analogy in my glaze workshops to baking bread. And the
bottom line to the analogy is that the same recipe in the hands of a good
baker will make a better tasting loaf of bread than in the hands of a bad
baker. A lot of it IS art, and some of it may even be magic. At least we
hope so.
Paul Lewing, Seattle
John Hesselberth on tue 17 feb 04
Of course, cone 6 ones do on remelting. See the dilatometer curves in=20
Chapter 5 of MC6G. I doubt cone 10 ones melt much higher, but Ron would=20=
have data on that.
Regards,
John
On Monday, February 16, 2004, at 08:32 PM, Ivor and Olive Lewis wrote:
> Dear William Schran,
> If what we are told about Eutectics were true, every one of our glazes
> would melt in the region of 700=BAC ~1300=BAF if they contained oxides =
of
> Sodium, Potassium, Silicon and Aluminium.
> Best regards,
http://www.frogpondpottery.com
http://www.masteringglazes.com
Ababi Sharon on tue 17 feb 04
What Bill had said was true when making a "mess" layering one on another
especially in uninformed layers. My humble experience also says that
mixing two glazes to one does not make the beloved mess.
By the way presence of coloring flux oxides even increase the mess
Unlike Ivor's humble experience (700=BAC ~1300=BAF) Mine says 700=BAC TO
1220=BA.....C!
=20
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
To Ceramics forum in Hebrew:
http://www.botzpottery.co.il/kishurim.html=20
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ivor and
Olive Lewis
Sent: Tuesday, February 17, 2004 3:32 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Layering glazes
Dear William Schran,
If what we are told about Eutectics were true, every one of our glazes
would melt in the region of 700=BAC ~1300=BAF if they contained oxides of
Sodium, Potassium, Silicon and Aluminium.
Best regards,
________________________________________________________________________
______
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.
Michael Wendt on tue 17 feb 04
Cindi,
I rely on layering to achieve almost all my scenic effects. The best
explanation I can give as to why the layering effects occur is mechanical
mixing during the melt (turbulence). At first glance, this seems unlikely
since the glazes are still viscous at cone but a number of things point to
this explanation. If two layers of liquids of miscible composition meet,
they will, given enough time diffuse into each other and become homogeneous.
You can verify that this happens with glazes by taking your favorite pair of
layering glazes and lap dipping a coaster to get thirds (1/3 glaze a, 1/3
glaze b over glaze a and 1/3 glaze b). Wash all the glaze off the lip,
underside and foot to avoid run off. Now fire this coaster in every load you
fire for the next few months. The first time you fire it, you get the broken
surface of the lap area you are used to. Each time you refire, the lapped
area will change as the two glazes are given more time to intermix.
Eventually, you should see a stable lap area that stops changing once the
two glazes have finished mixing.
In general, a number of transport mechanisms come into play. Gas development
in the body and glazes causes uneven eruptions that heal over during firing
and result in the variegation. Certain heavy oxides like Titanium settle in
the fluid glaze causing variegation due to flow as well. Someone also
suggested that some glaze overlays may result in a more fluid boundary
between the layers causing slippage and this would further enhance the
mechanical mixing. In this sense, the cause is mechanical mixing rather than
chemical interaction.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
wendtpot@lewiston.com
www.wendtpottery.com
Cindi Asked:
But why?
> If you're making your own, test some more, and check it out
> on a glaze program if you have one, since you'll know what
> the ingredients are.
Again, I am not tring to make this happen. I am trying to understand the
chemistry of why it happens. Testing will not help me with that.
Thanks
Cindi
Lee Love on wed 18 feb 04
Paul Lewing wrote:
>on 2/16/04 11:51 AM, Cindi Anderson at cindi@CINDI-ANDERSON.COM wrote:
>
>
>
>> I can't deal with things if I don't at least have a concept of
>>why they are happening.
>>
>Ah, Cindi, a right-brain thinker all the way!
>
Isn't this actually "left-brain" thinking? Rational/right,
Intuitive/left?
Lee In Mashiko, Japan {an (I)ntrovert i(N)tuitive, (F)eeling,
(P)erceptive type.}
Ivor and Olive Lewis on thu 19 feb 04
Dear John,
You say <curves in Chapter 5 of MC6G. I doubt cone 10 ones melt much higher,
but Ron would have data on that. >>
Yes, that happens and I would expect cone a mature cone ten glaze to
exhibit similar behaviour. I have good technical reasons to hope that
will happen.
But,..... you are talking of a recognised physical transition called
the Glass Transition Temperature. See Barsoum, M., "Fundamentals of
Ceramics" pp 311-314. 1997. ISBN. 0750309024. You are comparing
the behaviour of a glass to that of a mixture of minerals and chemical
compounds. One, within the limits of statistical distributions, is a
uniform amorphous solid. The other is a mixture dissimilar substances
which have been chosen to have melting points which make them
compatible with the clay to which they will be fired.
Cone ten glazes remelt at a much lower temperature than their
maturing temperature.
What technical and scientific grounds have you for claiming that the
materials in a glaze recipe have the same physical and chemical
properties as an amorphous glass even if they have the same empirical
composition expressed as Elemental Oxides?
A dilatometer does not record melting points, or does it?.... The one
I used for three years gave an indication of the changes in linear
dimension as temperature rose or fell and comparison with a specimen
which had a uniform rate of expansion enabled me to determine the
temperature and nature of Phase Changes which happened.
It is because of the phenomenon you describe that Frits, which are
made to be glassy, are so useful as promoters of fusion in Cone Six
Glazes. They provide that initial solvent activity whose existence
you, and other people, wish to deny. Yes, they commence melting in the
600-700=BAC range and do this without the help of any other substance.
Here is a simple question for folk to consider. Would any of you
deliberately put into your kin bisque or green ware with a superficial
coating applied to it which could become extremely fluid at 900=BA C,
then fire it to the vitrification point of your clay?
As I said before, read Ch 10 in Kingery et al.
My best regards to you.
Ivor Lewis. Redhill, South Australia
----- Original Message -----
From: "John Hesselberth"
To:
Sent: Wednesday, 18 February 2004 12:04
Subject: Re: Layering glazes
Of course, cone 6 ones do on remelting. See the dilatometer curves in
Chapter 5 of MC6G. I doubt cone 10 ones melt much higher, but Ron
would
have data on that.
Regards,
John
On Monday, February 16, 2004, at 08:32 PM, Ivor and Olive Lewis
wrote:
> Dear William Schran,
> If what we are told about Eutectics were true, every one of our
glazes
> would melt in the region of 700=BAC ~1300=BAF if they contained oxides
of
> Sodium, Potassium, Silicon and Aluminium.
> Best regards,
http://www.frogpondpottery.com
http://www.masteringglazes.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
Maurice Weitman on thu 19 feb 04
At 23:56 +0900 on 2/18/04, Lee Love wrote:
> Isn't this actually "left-brain" thinking? Rational/right,
>Intuitive/left?
Uhhh... no. Close, Lee, but not quite. Some (no names, please)
would even say it was opposite of your interpretation.
It's: Logical/left, Reactionary/right.
>Lee In Mashiko, Japan {an (I)ntrovert i(N)tuitive, (F)eeling,
>(P)erceptive type.}
Maurice - an ENFP (Enough! Now Frow Pots!) in Fairfax, California
where the wildflowers (Hound's Tongue and Shooting Stars - my
favorite! - today) are exploding in significant numbers and PG&E the
alleged electric utility (whose financial model was Enronned into
Chapter 11 last year) finally found the flaky pole so that every time
it rains or blows, the lights don't flicker.
Roly Beevor on thu 19 feb 04
Lee Love wrote ; Isn't this actually "left-brain" thinking?
Rational/right,
> Intuitive/left?
>
As I understand it the left brain serves the right side of the body, and is
the fine control, analytical, verbal side in right handed people, the right
brain is the intuitive, pattern processing side.
I think what happens is that the 'left brain' needs enough factual
information for it to accept that the pattern recognised by the 'right
brain' will work so that it shuts up and lets the right do its thing.
I wonder whether throwing the 'wrong' way would actually be a useful
exercise, it would certainly make one think differently?
Roly
John Hesselberth on thu 19 feb 04
On Wednesday, February 18, 2004, at 07:47 PM, Ivor and Olive Lewis
wrote:
Hello, Ivor,
>
>
> But,..... you are talking of a recognised physical transition called
> the Glass Transition Temperature. See Barsoum, M., "Fundamentals of
> Ceramics" pp 311-314. 1997. ISBN. 0750309024.
I think it may better be called the softening temperature. My
understanding of the glass transition temperature is that it is where
the volume vs. temperature curve changes slope. On the dilatometer
charts I referenced the glass transition temperature would appear to
occur at about 600C. The viscosity of the glaze decreases to the point
flow occurs at about 700--that is the point I was referring to.
> You are comparing
> the behaviour of a glass to that of a mixture of minerals and chemical
> compounds. One, within the limits of statistical distributions, is a
> uniform amorphous solid. The other is a mixture dissimilar substances
> which have been chosen to have melting points which make them
> compatible with the clay to which they will be fired.
> Cone ten glazes remelt at a much lower temperature than their
> maturing temperature.
> What technical and scientific grounds have you for claiming that the
> materials in a glaze recipe have the same physical and chemical
> properties as an amorphous glass even if they have the same empirical
> composition expressed as Elemental Oxides?
I didn't claim that. I merely pointed out that glazes melt at about
700C on remelting. That really is all I said.
> A dilatometer does not record melting points, or does it?.
The point where the curve bends over and goes south is where flow
starts to occur. Whether we call that the melting point or the
softening point we can debate--it is probably called the softening
point in most texts, although the term softening point is often defined
more precisely as the temperature at which the viscosity is about
10exp8 poise. But typical softening points as reported in Chemistry of
Glasses by A. Paul are in the range of 600-800C
> ... The one
> I used for three years gave an indication of the changes in linear
> dimension as temperature rose or fell and comparison with a specimen
> which had a uniform rate of expansion enabled me to determine the
> temperature and nature of Phase Changes which happened.
And for clay bodies that is usually all you get because dilatometers
usually don't go high enough in temperature to see the
melting/softening point. With glazes they do.
> It is because of the phenomenon you describe that Frits, which are
> made to be glassy, are so useful as promoters of fusion in Cone Six
> Glazes. They provide that initial solvent activity whose existence
> you, and other people, wish to deny.
You misunderstand me. I'm not denying that the solvent model is
applicable in some--maybe many situations. I am saying that it doesn't
explain--or I haven't seen the explanation-- all situations in which
mixtures of minerals or rocks melt. The zinc base glaze I described a
few days ago is one such situation--and I bet I can find similar
situations which involve 'normal' feldspars if neph sy, as you suggest,
is a special situation. The mineral nepheline, though, which is
embedded in neph sy has a reported melting point of 1200C also--so
unless there are some lower melting materials in the rest of the neph
sy rock, my question remains modified only slightly.
How do glazes that contain only high melting materials melt the first
time at a temperature below that of any of those high melting
materials??
You tell me I will have to wait at least several months to read your
writings in Ceramics Technical (it is only published twice a year) on
the subject so I remain curious and hoping I can provoke you to
disclose a little bit of what you seem to have learned.
Regards,
John
>
http://www.frogpondpottery.com
http://www.masteringglazes.co
Cindi Anderson on thu 19 feb 04
You have good instincts. I saw a book once called "drawing on the right
side of the brain" which is to help artists become more creative. They
recommend drawing left handed for this reason. (I'm not sure what they say
if you are already left handed, should you draw/throw righthanded then?)
However creativity has never been one of my problems. I actually am a
pretty solid mix of left and right. Sometimes I'm just an artist, and I
want to know as little as possible about the technical aspects. Other
times I want to know. Whenever I take personality tests they have a hard
time with me because I am half way between both traits (practically
regardless of what the trait is they are testing). Usually the
"interpretations" say people like me have trouble because we have so many
options of ways to be, that this makes us unhappy :-) I can kind of relate,
but I have found a good way to live with it. It seems to me there are many
on ClayArt who are this way; artistic and analytical.
Someone made the analogy about the "art" of replacing ingredients. Vinegar
for wine for example. But this is not art, it is knowledge. You have to
know what things work as substitutes for what, or you can't make such
substitutions. You might not take the last step of knowing chemically why
they behave the same, but you have learned it from somebody (maybe your
parents or grandparents). I believe "art" only comes into cooking as you
refine recipes based on your own preferences. You prefer a pinch more of a
spice. You wonder if a pinch of something else will give some type of
flavor, so you try it. Or you invent a recipe on your own, merging many
pieces of knowledge you have accumulated with your own original ideas.
There is always a lot of knowledge there, and I suspect more understanding
of "how things work" than you suspect. (I'm pretty sure a good cook knows
scientifically why a cake falls when you slam the oven door.)
Cindi
----- Original Message -----
> I wonder whether throwing the 'wrong' way would actually be a useful
> exercise, it would certainly make one think differently?
Ivor and Olive Lewis on fri 20 feb 04
Dear John,
Agreed, Glasses soften, then start to flow as temperature increases.
But glaze formulations which have not previously been fired do not
melt in that temperature range, say 700 - 800=BA C even though it may be
claimed there are "Eutectics", given in terms of Elemental Oxides
within their chemical compositions, which cause melting.
I have read no account better than that given by Kingery, Bowen and
Uhlmann to explain melting behaviour of ceramic materials.
Best regards,
Ivor Lewis. Redhill, South Australia
Lee love on fri 20 feb 04
Cindi Anderson wrote:
>of "how things work" than you suspect. (I'm pretty sure a good cook knows
>scientifically why a cake falls when you slam the oven door.)
>
>
>
Because you offend the Kami of the oven? 8-)
There certainly are different ways to understand this and from Asian
mindfulness practice, you might not be too far off the mark when
thinking about the "Spirit" of the oven.
Like my late teacher, Dainin Katagiri Roshi used to say, "When
you are not careful about not using too much toilet paper, you do not
take care of 'the Life of the toilet paper.'" Slamming the oven door
can be as much about respect and reverence as it is about "science."
Lee in Mashiko, Japan http://mashiko.us "It seems to me what you lose
in mystery you gain in awe" -- Francis Crick
Gene Arnold on mon 20 dec 04
Recently I have started to experiment with layering glazes, and have had =
a lot of problems with the glazes peeling, cracking and in general =
falling off. Some glazes seem to be worse than others but so far all I =
have tried have done this to some degree. When I manage to get some to =
hold on and get them fired they all seem to exhibit some amount of =
crawling, some bad some not so bad. A sign that the glaze is too thick =
I'm guessing. None of the glazes do this on their own unless I apply =
them to thick.=20
I fire to cone 6 ox. Some of the glazes came from MC6G. Others I have =
picked up here and there.
So what I' asking is how do you use multi layers of glaze with out =
getting them too thick???
Is there some trick to getting the multi layers to stick to each other =
and not crawl ???
Would adding CMC to the glazes help them stick to each other better and =
not crack??? If so how much???
Gene & Latonna
mudduck@mudduckpottery.com
www.mudduckpottery.com
Michael Wendt on tue 21 dec 04
Gene,
One method that helps with layering is applying more than one layer before
the underlying layers have a chance to dry. One of the demonstrations in my
plate video is a method that uses turkey basters to layer while the glazes
are still wet so that they mix mechanically one the surface to produce
complex visual effects not possible by any other means.
I also have worked hard to develop base glazes that have the right amount of
clay in them. Too much leads to excessive shrinkage and crawl due to drying
cracks and shrinkage cracks. Too little also causes a host of problems
including dusty, difficult to layer surfaces.
One laborious method we occasionally employ when all else fails is to bisque
fire between layers to "set" the layer and make it strong and bonded to the
pot.
We rarely use this method because it is too slow for production in our
setting.
Note: if your glaze contains a lot of clay, bisque fire a bowl of the dry
mixed glaze with colorant and all and add it in small increments to your
mixed batch.
If there is too little clay, the glaze surface will be dusty and easy to rub
off. Mix 2-3 lbs of Veegum in 4 1/2 gallons of water and keep it tightly
lidded so you can take a teaspoon or two of the veegum gel and add it to
your glazes a little at a time until they work without crawling or settling.
Keep records of what you do and make ONE small change at a time so you can
be sure of why a particular change works or not.
Good Luck,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Gene wrote:
Recently I have started to experiment with layering glazes, and have had a
lot of problems with the glazes peeling, cracking and in general falling
off. Some glazes seem to be worse than others but so far all I have tried
have done this to some degree. When I manage to get some to hold on and get
them fired they all seem to exhibit some amount of crawling, some bad some
not so bad. A sign that the glaze is too thick I'm guessing. None of the
glazes do this on their own unless I apply them to thick.
I fire to cone 6 ox. Some of the glazes came from MC6G. Others I have picked
up here and there.
So what I' asking is how do you use multi layers of glaze with out getting
them too thick???
Is there some trick to getting the multi layers to stick to each other and
not crawl ???
Would adding CMC to the glazes help them stick to each other better and not
crack??? If so how much???
Gene & Latonna
Cindy on tue 21 dec 04
Dear Gene,
There aren't really any rules to layering glazes, except that you don't want
to get them too thick, as you have noticed. I don't know your usual
practices in dipping glazes. I don't do a lot of layering, so I like to have
my glazes at a thickness that allows me to dip and remove pretty quickly.
This is just a function of adjusting the amount of water in the glaze.
Since you're having trouble with your overlap, you may want the glazes a
little thinner. If you dip twice, try dipping the area that will be
overlapped only once. If you dip and count to ten or whatever, figure out a
way to have the overlap area under the glaze for a much shorter count than
the rest of the pot.
Make your secondary glaze thinner than you would have it if you were using
it as the primary glaze. If you're dipping, do it quickly. If you're pouring
on the secondary glaze, rub off any bumps once it's dry or nearly dry. If
you get cracks, try to blend them together with your finger, and make the
primary or secondary glaze thinner in the future. If the glaze is flaking
off, you need to wash the pot, dry thoroughly, and try again later with a
thinner glaze. Should you choose to fire a pot you're suspicious may have
too thick a glaze coat, make sure to use a cookie to protect your kiln
shelf.
If you are using a matt and a glossy glaze together, it usually works better
to use the matt glaze as the foundation. Two matt glazes generally
disappoint if you're looking for glaze movement.
With glossy glazes, the thicker the glaze is, the more movement and
intermingling you can expect. It also helps to soak the glaze at peak
temperature. However, more movement means more chance of glaze drips on the
shelf, so this can easily get to be too much of a good thing. I love the
interaction between the two glazes, and to maximize this, I use a turkey
baster or ear syringe to drip the secondary glaze over the edges of the pot.
Just be sure to wipe off the ends of the drips or your pots *will* be stuck
to the shelf.
Have fun, don't give up, and Merry Christmas!
Cindy in SD
Frances Howard on sat 16 jul 05
When one is layering glazes, e.g. chun white under licorice or slate blue or chun white over licorice or slate blue, or using Mel's advice of three base glazes with different oxides added, what is it that keeps the layers apart in the heat of the kiln? The fired effects are all so different. To the non chemist one would assume that everything would mix together like a cake, though I know that it doesn't. But I don't know why. I guess there's any easy answer. Could anyone tell me please?
Daniel Semler on sat 16 jul 05
Hi Frances,
To draw on your cake analogy I would answer this way. The cake ingredients do
not mix because of the heat of the oven. They are mixed when they go
in. If you
make a marble cake for example, you three portions of the cake batter
and colour
each differently. You then add each to the pan one at a time and swirl them
together a bit. When it comes out you have nice swirls of different colours,
not a single beige cake for eg.
Glazes melt at temperature to greater and lesser degrees. They do not melt to
a low viscosity liquid unless there's been a mistake (overfire, incorrect mix
etc.) so they do not mix like orange juice and water, ie. pretty much of their
own accord when one is added to the other. If they did they would not
be on the
pot at the end. Thus they cannot mix 100% in this way. Actual mixing that does
occur arises due to things like bubbling of gases from the body and the glazes
causing them to intermix a bit. Chemists would be able to expand on this I
think, but the water gets a little deep for me just about here :)
Thanx
D
Ron Roy on tue 19 jul 05
Hi Frances,
If we soaked long enough I would expect them to get mixed completely.
As it is - we usually turn our kilns off shortly after the glazes are
melted - so they don't have enough time to get together much.
RR
>When one is layering glazes, e.g. chun white under licorice or slate blue
>or chun white over licorice or slate blue, or using Mel's advice of three
>base glazes with different oxides added, what is it that keeps the layers
>apart in the heat of the kiln? The fired effects are all so different.
>To the non chemist one would assume that everything would mix together
>like a cake, though I know that it doesn't. But I don't know why. I
>guess there's any easy answer. Could anyone tell me please?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
karen gringhuis on fri 28 apr 06
Randy -
These are not specific overlaps but general
descriptions of what has worked for me. I've not
tested these concepts in multiple bases but I think
they should work.
Color a transparent glossy base with Mason Vicky Green
and Cerdec (or perhaps a Mason) yellow to get
chartreuse. Layer it over a satin matt base with MgO
colored w/ cobalt to give lavender blue. Try same
idea with glossy base colored with Cerdec red. The
overlap will move so keep it up from the very bottom
of a pot. The overlap area gave me cobalt blue with a
runny bottom edge of the overlapping color.
Take a satin matt base and color it with Cerdec
yellow; make separate batch of same base colored with
orange. Put yellow on top of orange to get a nice
mango with some breakup.
Karen Gringhuis
KG Pottery
Box 607 Alfred NY 14802
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Angela Davis on mon 1 sep 08
Do you have a pyrometer? Do you know what temp
you actually reached?
The surface looks like satin marble.
Angela Davis
----- Original Message -----
From: "Randy McCall"
To:
Sent: Sunday, August 31, 2008 9:27 PM
Subject: Layering Glazes
> Could I get a critique on the layering of the glazes on this pot? The
> overall result was a smooth buttery nice feeling glaze with some texture
> in
> areas. I will be working to see if I can replicate this in future
> firings.
> I have been working to this end for a couple of years. Fired to a hard
> cone
> 6 in electric. When the sitter falls I continue high heat for 10 more
> minutes then natural cool to 1650 F hold for one hour. The glaze surface
> is
> as close to Cone 10 firing appearance as I have seen at Cone 6. 4 glazes
> were used.
>
> The picture is at this link
>
> http://members.tripod.com/~McCallJ/image/obj58geo55pg1p3.jpg
>
>
>
> Randy
>
> Cotton Patch Pottery
> members.tripod.com/~McCallJ/index.html
Steve Dalton on mon 1 sep 08
Hi Randy,
The picture in the link did not come up. You might want to check it.
Steve Dalton
Clear Creek Pottery
Snohomish, WA
--- On Sun, 8/31/08, Randy McCall wrote:
> From: Randy McCall
> Subject: Layering Glazes
> To: CLAYART@LSV.CERAMICS.ORG
> Date: Sunday, August 31, 2008, 6:27 PM
> Could I get a critique on the layering of the glazes on this
> pot? The
> overall result was a smooth buttery nice feeling glaze with
> some texture in
> areas. I will be working to see if I can replicate this in
> future firings.
> I have been working to this end for a couple of years.
> Fired to a hard cone
> 6 in electric. When the sitter falls I continue high heat
> for 10 more
> minutes then natural cool to 1650 F hold for one hour. The
> glaze surface is
> as close to Cone 10 firing appearance as I have seen at
> Cone 6. 4 glazes
> were used.
>
> The picture is at this link
>
> http://members.tripod.com/~McCallJ/image/obj58geo55pg1p3.jpg
>
>
>
> Randy
>
> Cotton Patch Pottery
> members.tripod.com/~McCallJ/index.html
sacredclay on mon 1 sep 08
Randy, I love the look! a dear friend who now has Lou Gehrig's used to
take three glazes and held the pot horizontal and pour them all over
each other. Beautiful movements and everyone would be anxious to see
how it all came out of the kiln. Try glazing it horizontal rather than
vertical. There's more interesting patterns that way. Have fun!
Kathryn Hughes in NC
Randy McCall on mon 1 sep 08
Thanks for the suggestion..........
Randy
English Setters
members.tripod.com/~McCallJ/MCCALL2.html
Cotton Patch Pottery
members.tripod.com/~McCallJ/index.html
----- Original Message -----
From: "sacredclay"
To:
Sent: Monday, September 01, 2008 2:27 PM
Subject: Re: Layering Glazes
Randy, I love the look! a dear friend who now has Lou Gehrig's used to
take three glazes and held the pot horizontal and pour them all over
each other. Beautiful movements and everyone would be anxious to see
how it all came out of the kiln. Try glazing it horizontal rather than
vertical. There's more interesting patterns that way. Have fun!
Kathryn Hughes in NC
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