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glazing

updated tue 27 feb 07

 

Joyce Lee, Jim Lee on fri 10 oct 97

Do I empathize with the clayarter who said she had trouble with glazing
and wanted to know if the rest of us had any techniques to share! I do!
Thank you from me, too, for sharing, especially Mel's two-inches-at-a-
time on a tall vessel in order to have better understanding of a
specific glaze. Perfect! I'm one of the "don't look at my picture yet;
it's not ready" former first-graders (missed kindergarten...almost
ruined my life) who could never stay in the lines when she colored.
Turned out this was one of my first lessons in "experience counting,"
since I stay in the lines very well indeed now, and have for years.
Sooo, armed with clayarters' suggestions, I'll march back in the studio
and face those several hundred bisqued pots whose self-esteem I haven't
had the nerve to demolish with my lousy glazing methods. Maybe I will
ruin their futures, but I'm hoping to gain the experience needed to
enhance the lives of pots yet unborn. Thanks again from me, too.

Joyce
Ever hopeful in the Mojave

Wilkinson on sat 11 oct 97

Unbelievable how many personal notes I have gotten from potters that have
received so little class time regarding glaze application verses other
aspects of pottery making and are in a dilemma over glazing pots asking me
to share any info I have gotten. Well, you have all seen pretty much what
has been shared so I ask anyone that can to please contribute to this
thread. There are quit a few looking for the help. TIA

Lori Wilkinson

LorWilk@dfn.com
http://www.geocities.com/SoHo/Gallery/1165

Tom Morris on sun 12 oct 97

I have had my share of glaze problems myself... last bunch I used Duncan
Infinity glaze on.... the glaze came out like shaving cream!!! It powdered
to the touch. revealing a hard crazed layer below... oh well...
If I mess up the glaze, usually a few licks with 200 grit wet/dry silicon
carbide sandpaper (wet) takes the S*** right off.

Thankful for the abrasive....
Tom Morris
a.k.a. TomMorris`

Corinne P. Null on tue 14 oct 97

This is not really a glazing technique, but something I have found very
useful relating to glazing.

Whenever I mix a new test glaze, I prepare a slew of test tiles and try my
current glazes over and under the new glaze. This increases the possible
uses for a new glaze, and sometimes renders serendipidous results.



At 09:07 AM 10/11/97 -0400, you wrote:
>----------------------------Original message----------------------------
>Unbelievable how many personal notes I have gotten from potters that have
>received so little class time regarding glaze application verses other
>aspects of pottery making and are in a dilemma over glazing pots asking me
>to share any info I have gotten. Well, you have all seen pretty much what
>has been shared so I ask anyone that can to please contribute to this
>thread. There are quit a few looking for the help. TIA
>
>Lori Wilkinson
>
>LorWilk@dfn.com
>http://www.geocities.com/SoHo/Gallery/1165
>
Corinne Null
Bedford, NH

cnull@MCIONE.com (New e-mail address)

Joyce Lee, Jim Lee on sat 18 oct 97

This post is NOT for rocket scientists, physicists, professional
potters etc. It is meant for those, such as I, who have felt stress
when attempting to glaze their pots. One little trick to getting
supposedly breaking-glazes to break (such as Woo Blue and, especially,
some shinos) is to barely, ever so lightly, lightly, pat the part you
want to break with a wet finger. This, of course, helps to thin the
glaze on that part of the pot (rim, decoration, resisted or eroded area
etc) without disastrously disturbing the glaze. Our community college
teacher passed this tip on and demonstrated, but I still only achieve
the orange/rust break of shino occasionally. Demonstrations will go so
far; after that, it's experience. I now have around 400 pots to glaze
and hope completing the job will enhance my glazing skills which, up to
now, are rather pitiful too often...not always, though; sometimes I'm on
target, but am seldom sure of cause and effect. I have observed MANY
demonstrations by our patient teacher. Looks easy. NOT. But, like you
other intermedies, with experience I WILL get there.

Joyce
In the Mojave recalling my first spray-glazing experience. One side of
that largish lidded pot was sprayed way too thick, the other way too
thin, and I never was able to tap the lid off. This was after I'd
observed mucho sprayings by others. Experience COUNTS.

Joyce Lee, Jim Lee on fri 7 nov 97

Before I jump in and fire some bowls about which I have concern, I think
I'd better ask a question. I'm glazing bowls with a copper purple glaze
gleaned from the Mesa Art Center. On the pot in its dry form, the glaze
has a crackled appearance in areas. These "crackles" sort of lift from
the pot. In your experience, will this glaze pull further away from the
pot and leave blank spaces when fired? Or will it flatten out and cover
the bowl? This is ^10 reduction. It looked fine on a test tile, but it
didn't "crackle" either. Poorly worded, I know, but the best I can do at
the moment. I would just go ahead and fire and learn from the
experience, but I can't afford to lose these bowls right now since I
have no idea how many pots one should take for a two-day Christmas sale.
Thank you for not deleting and perhaps thinking about a response.

Joyce
In the Mojave going to do something frivolous like watch "Friends."

Marion Barnes-Schwartz. on sat 8 nov 97

My experience is that the glaze will further "craze" and separate during the
firing. When I come across glazed bisque ware that has these cracks in it, I
rub my finger over the surface of the dry glaze to smooth out and fill in the
cracks. This will usually work, but individual glazes may react differently.

the cat lady on sat 8 nov 97

At 08:06 AM 07/11/97 EST, you wrote:
>----------------------------Original message----------------------------
>Before I jump in and fire some bowls about which I have concern, I think
>I'd better ask a question. I'm glazing bowls with a copper purple glaze
>gleaned from the Mesa Art Center. On the pot in its dry form, the glaze
>has a crackled appearance in areas. These "crackles" sort of lift from
>the pot. In your experience, will this glaze pull further away from the
>pot and leave blank spaces when fired? Or will it flatten out and cover
>the bowl? This is ^10 reduction. It looked fine on a test tile, but it
>didn't "crackle" either. Poorly worded, I know, but the best I can do at
>the moment. I would just go ahead and fire and learn from the
>experience, but I can't afford to lose these bowls right now since I
>have no idea how many pots one should take for a two-day Christmas sale.
>Thank you for not deleting and perhaps thinking about a response.
>
>Joyce
>In the Mojave going to do something frivolous like watch "Friends."
>
>
Hi Joyce:

I don't fire redux, but I *do* fire to ^10.

I have an overlap glaze that always "alligators" (lifts up as you described)
on me (you can see this overlap combo on my homepage on the cream n'sugar).

Anyway, I wait til the glaze is almost dry, then rub the lifted parts flat.
Wait til the glaze is _bone_ dry, then rub any lifted parts again. If
lifted excessively, I've resorted to a light spray of water (very, very
light!!) and rubbed again when almost dry; then dry.

My (hard won) experience is that if you don't flatten the glaze, it will
leave/crawl during firing. I've got a less than 5% loss rate now that
I rub these lifts.

I've been advised that calcining the EPK before adding to the glaze will
help, but before I received that advise, I mixed up a full garbage can!

I hope this helps you - it isn't gospel, just what I've experienced.

sam - alias the cat lady
Melbourne, Ontario
SW Ontario CANADA
http://www.geocities.com/paris/3110

Debby Grant on sat 8 nov 97

Dear Joyce,

You must rub the cracked glaze down firmly onto the pot with your
finger or a sift tissue. Otherwise the glaze will probably crawl in
the firing and might even spit off the pot.

Good luck, Debby Grant in NH

Kris Baum on sat 8 nov 97

Joyce -

I've had similar experiences and ... sometimes they heal over and
sometimes they don't, depending on the glaze. One suggestion is to
use a wet finger or wet sponge and gently press down the edges of the
glaze; by dampening them you could then rub your finger over the
glaze and help to heal the cracks. I have had success with this
method. Good luck.
===============================================
Kris Baum, Shubunkin Pottery
mailto:shubunki@erols.com
===============================================

Lisa P Skeen on sat 8 nov 97

Joyce,
Unfortunately, my experience says you're gonna see some bald patches if
you fire the bowls like this. Try rubbing out the cracks with your
fingers. If that doesn't work, and you're not comfortable dabbing glaze
on with a paintbrush, I'd go for the "wash it off and start over"
technique.


Lisa Skeen, Living Tree Pottery and Soaps
http://www.uncg.edu/~lpskeen
"We will have to repent in this generation not merely for the hateful
words of the bad people, but for the appalling silence of the good
people." MLK, 4/63

On Fri, 7 Nov 1997 08:06:46 EST "Joyce Lee, Jim Lee"
writes: On the pot in its dry form, the
>glaze>has a crackled appearance in areas. These "crackles" sort of lift
>from>the pot. In your experience, will this glaze pull further away from
>the>pot and leave blank spaces when fired?

Jeff Lawrence on sat 8 nov 97

Joyce in the Mojave was inviting conjecture on her unfired glazed bowls:
> On the pot in its dry form, the glaze
>has a crackled appearance in areas. These "crackles" sort of lift from
>the pot. In your experience, will this glaze pull further away from the
>pot and leave blank spaces when fired? Or will it flatten out and cover
>the bowl?

Hi Joyce,

The last ^10 reduction mugs I made had the same crackled appearaance before
firing (they might have been a little damp, too). After firing, the glaze
crawled dramatically -- the surface was covered with uniform little beads
like those candy beads I used to get on strips of paper.

I thought it looked really interesting, so I brought one home to show my
wife. She refused to allow it in the house, on the grounds that
(1) it gave her the creeps
(2) we might catch some horrible condition from it

Similar pieces came out without crawling when I finger-smoothed all cracks
in the dry glaze, which might be advisable if you aren't into shock art.

Best regards,
Jeff
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt 3 Box 220
Espanola, NM 87532
ph 505-753-5913
fax 505-753-8074

Peggy Heer on sat 8 nov 97

Hi Joyce...sounds like you have the glaze on a bit toooo thick. If it is
REALLY lifting then reglaze the bowls. It will crawls off/apart. If it
just has surface cracks then run your finger over the cracks and leave for
a bit..if they reappear...reglaze..if not ... they should fire ok. Good
luck. As Always in Clay Peggy

>----------------------------Original message----------------------------
>Before I jump in and fire some bowls about which I have concern, I think
>I'd better ask a question. I'm glazing bowls with a copper purple glaze
>gleaned from the Mesa Art Center. On the pot in its dry form, the glaze
>has a crackled appearance in areas. These "crackles" sort of lift from
>the pot. In your experience, will this glaze pull further away from the
>pot and leave blank spaces when fired? Or will it flatten out and cover
>the bowl? This is ^10 reduction. It looked fine on a test tile, but it
>didn't "crackle" either. Poorly worded, I know, but the best I can do at
>the moment. I would just go ahead and fire and learn from the
>experience, but I can't afford to lose these bowls right now since I
>have no idea how many pots one should take for a two-day Christmas sale.
>Thank you for not deleting and perhaps thinking about a response.
>
>Joyce
>In the Mojave going to do something frivolous like watch "Friends."

Peggy Heer / Heer Pottery E-Mail p4337@connect.ab.ca
52120 Range Road 223
Sherwood Park, AB. Canada T8C 1A7
Phone (403) 922-6270
http://www.ffa.ucalgary.ca/artists/pheer/

Samantha Parsons and Don Snyder on sun 9 nov 97

Joyce - me again. I read somewhere about a potter having cracks in
unfired dried glaze. He carefully rubbed them smooth and had no problem
with crawling - didn't mention whether it was done wet or dry though;
but since you are getting ready for SAS maybe you won't want to try
this; just thought I'd throw it in in case you hadn't heard of it. I
had several bowls with crazed glaze last semester and none of them
crawled also. Again - good luck with them, I am eager to see how they
come out....Sam

Paul Jadick on sun 9 nov 97

This is an attempt to respond to two people with glazing problems. First
Joyce, who had glaze cracking and lifting off her bowls in the dry state.
Without getting into all of the possibilities of why this could happen,
which I would want to research further, let's get simple first... Maybe the
glaze is too thick.. But, since it is on the pots already... If it is
lifting on the outside, it may fall off and land on your shelf. On the
inside, unless it is a flat surface, it may not lie down and melt nicely
either. I would take a fine spray bottle and lightly spray then to dampen
(not dripping) and see if it lies back down. Then, as it starts to dry
again and begins to crack again, smooth it with your finger before it
lifts. I hope this helps.

Now for the person with the porcelain mugs. Maybe your glaze is too thick.
Some glazes apply better if you use two thinner coats. When you dunk with
your tongs, hold the cup upside down until it stops dripping. Then there
should be nothing left to run down the side. If the glazing job looks
really bad before firing (smudged and smeared) wash it off, it probably
won't get any better! Glazing is not as easy as it may seem and very time
consuming to do well. Hope this helps.

Georgia Tenore
pjadick@worldnet.att.net

Tony Hansen on tue 11 nov 97

I've been watching some of the messages about what to do when glaze
cracks during drying. It seems to be that if the glaze forms flakes
with curled up edges its fragile-at-best bond with the bisque is
severely compromised. Rubbing it down is a little like ignoring that
chest pain you've been having. There is a deeper problem.
A glaze with the right amount of clay and properly gelled will easily
dry without flaking and it will be go on in a very even silky
layer without drips.

In all but the most exotic specialized glazes I would not tolerate
this. It is better to use a good base glaze with 20% or so kaolin and
there will be no problem. There are a lot of flux saturated recipes
out there with almost no clay and this problem is common.

--
-------
T o n y H a n s e n thansen@digitalfire.com
Get INSIGHT, Magic of Fire at http://digitalfire.com

MDJOAN@AOL.COM on wed 11 sep 02


I am a new student and I'd like to know why my slip decorated piece flattened
out during the clear glazing fire when the piece already came out perfect
after bisque firing? I used red earthenware clay and fire at cone 04.

Any help you send will be appreciated

Thanks...

Ababi on wed 11 sep 02


Clear glaze is a disaster to terra cotta in low fire!
red clay , the iron moves through. you must have first a truly thick white slip otherwise
the claybody fights with your slip and wins and the glaze swallow the rest of the
colors!
Make a small test: Take an oil pastel, I think you call them creaon or crion.
Please take yellow red and green.
Test one: One line each colors on a white paper.
test two, the same power, the same color on brown paper. See the difference?
If you love the red claybody try majolica glaze look here:
http://digitalfire.com/magic/majolica.htm.
I don't know if there are recipes in this article. You must be aware, in some books they
give majolica bases for low fire with lead. Read the book not the lead.
Please see in this page:
http://members4.clubphoto.com/ababi306910/775033/
Slide 10 where I applied a very thick white slip on the greenware
Slide 11) the way it looked after bisque.
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
---------- Original Message ----------

>I am a new student and I'd like to know why my slip decorated piece flattened
>out during the clear glazing fire when the piece already came out perfect
>after bisque firing? I used red earthenware clay and fire at cone 04.

>Any help you send will be appreciated

>Thanks...

>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org

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

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

Snail Scott on wed 11 sep 02


At 09:46 AM 9/11/02 EDT, you wrote:
>I am a new student and I'd like to know why my slip decorated piece flattened
>out during the clear glazing fire when the piece already came out perfect
>after bisque firing? I used red earthenware clay and fire at cone 04.


You mean that the piece itself slumped and flopped?
Are you sure that the final firing was only ^04?
How high was the bisque? Have you fired the same clay
before under the same conditions? It's rare for a
commercial earthenware to warp at ^04.

-Snail

Evan Clifford on wed 11 sep 02


What cone did you glaze fire to?
-Evan

Michigan weather... what can you do??


-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG] On
Behalf Of MDJOAN@AOL.COM
Sent: Wednesday, September 11, 2002 9:47 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: glazing

I am a new student and I'd like to know why my slip decorated piece
flattened
out during the clear glazing fire when the piece already came out
perfect
after bisque firing? I used red earthenware clay and fire at cone 04.

Any help you send will be appreciated

Thanks...

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

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

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

John Stark on sun 25 feb 07


I know there must be a secret to putting an underglaze over a primary =
glaze and having it sink in to achieve that wonderful juicy look. When I =
have tried it,it just sat there, no intermingling.

Sondra in beautiful coastal SC

Marcia Selsor on sun 25 feb 07


Sondra,
An underglaze should go under not over the glaze. The juicy quality
is from the glaze being over it.
Underglazes will not flux to be juicy.
Some overglaze decorating colors can be used at some high
temperatures. Maybe try that for the effect you are seeking. Or you
could try some colorants into a small sample of the glaze or another
glaze over your base glaze.

Marcia Selsor
http://marciaselsor.com

Snail Scott on sun 25 feb 07


At 01:12 PM 2/25/2007 -0500, you wrote:
>I know there must be a secret to putting an underglaze over a primary
glaze and having it sink in to achieve that wonderful juicy look. When I
have tried it,it just sat there, no intermingling...


I can't think how any but the thinnest
coating of a nonvitreous engobe would
melt into a glaze. It would need to be
fairly well-fluxed in its own right, or
else thin enough for the glaze fluxes
underneath it to work on it and create
an 'interface' layer all the way through,
or both.

Note, however, that the term 'underglaze'
is incredibly, almost uselessly general.
It can apply in the manner I have assumed
above, to describe a nonvitreous engobe
(either a 'plain slip' or a modified one).
It can also refer to a glaze applied
underneath another glaze, even if both
glaze mature at similar temperatures. It
can even (more rarely) refer to any clay
surface treatment that gets glaze over
top of it, such as an oxide wipe. The
term 'overglaze' is similarly nonspecific,
referring to the second of two glaze
coatings, or to lower-fired subsequent
coatings such as ceramic enamels, china
paints, and overglaze lusters.

There are more things which can be properly
termed 'underglaze' than just those handy
manufactured engobes which are labeled as
such. Underglaze refers to its sequence
in a process (i.e. anything which gets
covered by a glaze later on), not to any
particular class of substance.

So, perhaps you are reading a reference to
a coating of a second glaze ('overglaze')
applied to an initial coating of a first
glaze ('underglaze'), and both glazes
mature at similar (though not necessarily
identical) temperatures. This type of
combination will often give the 'juicy'
look you spoke of.

-Snail

Lee Love on mon 26 feb 07


It is good if both glazes (not underglaze and glaze) like to move
in the firing. You can see an example from my show card. My
standard ash glaze as a base with glaze trailed kaki, nuka jiro and
Reeve chrome green:

click on image for larger image (example is lower image. Top image
shows a Shigaraki piece with immovable inlay and straw ash lines.
These are a good contrast):

http://photos1.blogger.com/x/blogger/5921/136/1024/31372/image0.jpg

You can see both sides of the card here:

http://potters.blogspot.com/2006/12/gallery-shunn-tokyo-january-24-28-2007.html

--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/

"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau

"Let the beauty we love be what we do." - Rumi