Marianne Lombardo on sat 4 may 02
Generally I brush on my glazes, but I like the Red Gold so much on the =
outside of vessels that I made up a small bucketful and decided to try =
my hand at dipping the mugs into the glaze.
The first mug slipped out of my fingers and fell right into the bucket. =
So I took it over to the sink and had to scrub quite a while to get all =
the glaze off and try again. On that mug the next morning the glaze was =
still wet looking and took a long time to dry.
The claybody was Tucker's MCS porcelain ^6. When I placed the set in =
the kiln I noted the position on the shelf that I placed that particular =
mug.
Now this is really odd. The other 3 mugs, the creamer and sugar bowl =
all crazed. Big long craze lines spaced about 1/2 inch apart. No big =
deal, I thought it might on porcelain but was willing to take a chance. =
The odd thing is the mug that was overly wet and took forever to dry, =
did not craze. Not a bit. And, it was the *only* piece of the set that =
the glaze did not run right off onto the shelf. At the bottom the glaze =
pooled and set and held in the indentation I make in the foot, but only =
on that one mug.
The only variables with that one mug are that it was very wet when I =
glazed it, and it was placed a bit closer to an element than the others.
I also applied two other glazes on the rims, but the application was =
consistent with all pieces.
Only this one mug will give off a nice musical pingggg when I flick it =
with my finger.
Marianne Lombardo
Omemee, Ontario, Canada
Maid O'Mud on sat 4 may 02
Hi Marianne:
You have a huge clue staring at you. A wet mug (freshly and thoroughly
soaked) absorbs WAY less glaze than a dry mug, so while you may have dipped
the wet and dry mugs the same way, in fact the application was NOT
consistent.
To find out how mug "less" glaze was applied you'd have to glaze a wet and a
dry mug (weigh them 1st) and let them dry for a few days and then weigh
again. I'm terrible at math, but somewhere in here is a calculation that
will allow you to water down your glaze sufficiently to get the effect of
the one good mug. Perhaps someone else can step forward and explain the
calcs needed. I'm dyslexic with numbers.....
Sam - Maid O'Mud Pottery
Melbourne, Ontario CANADA
"First, the clay told me what to do.
Then, I told the clay what to do.
Now, we co-operate."
sam 1994
From: Marianne Lombardo
said in part
Now this is really odd. The other 3 mugs, the creamer and sugar bowl all
crazed. Big long craze lines spaced about 1/2 inch apart. No big deal, I
thought it might on porcelain but was willing to take a chance. The odd
thing is the mug that was overly wet and took forever to dry, did not craze.
Not a bit. And, it was the *only* piece of the set that the glaze did not
run right off onto the shelf. At the bottom the glaze pooled and set and
held in the indentation I make in the foot, but only on that one mug.
The only variables with that one mug are that it was very wet when I glazed
it, and it was placed a bit closer to an element than the others.
I also applied two other glazes on the rims, but the application was
consistent with all pieces.
Only this one mug will give off a nice musical pingggg when I flick it with
my finger.
Judith I. Marvin on sat 4 may 02
Maryanne - My guess is that the glaze was much thinner on the water soaked
mug.
>
>The first mug slipped out of my fingers and fell right into the bucket. So
>I took it over to the sink and had to scrub quite a while to get all the
>glaze off and try again. On that mug the next morning the glaze was still
>wet looking and took a long time to dry.
>
>>__________________________________________________________________________
____
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
_________________________________________________________________
Send and receive Hotmail on your mobile device: http://mobile.msn.com
Dannon Rhudy on sat 4 may 02
At 11:11 AM 5/4/02 -0400, you wrote:
>Generally I brush on my glazes, ....
had to scrub quite a while to get all the glaze off and try again.
... next morning the glaze was still wet looking and took a long time to
dry.
;
... The other 3 mugs, ..... all crazed. .... the mug that was overly wet
and took forever to dry, did not craze....
So, it sounds like the glaze that did NOT craze was on much
thinner than the other specimens. When you wash a piece of
bisque it absorbs water. When it has water in it, it takes
less glaze. It took long to dry because the clay was
saturated with water, and the water in the GLAZE had no
where to go except through evaporation.
So you learned a lot about that glaze on that clay, wet and
dry, brushed and dipped. Too thick glazes will often craze
when they would not, or not so obviously, if applied thinner.
The fact that the other pieces "ran off onto the shelf" should
be a pretty good clue that there was too much glaze on the
work.
regards
Dannon Rhudy
Not a bit. And, it was the *only* piece of the set that the glaze did
not run right off onto the shelf. At the bottom the glaze pooled and set
and held in the indentation I make in the foot, but only on that one mug.
>
>The only variables with that one mug are that it was very wet when I
glazed it, and it was placed a bit closer to an element than the others.
>
>I also applied two other glazes on the rims, but the application was
consistent with all pieces.
>
>Only this one mug will give off a nice musical pingggg when I flick it
with my finger.
>
>Marianne Lombardo
>Omemee, Ontario, Canada
>
>___________________________________________________________________________
___
>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.
>
>
Michele Williams on sat 4 may 02
Boy, does this report beg for experimenting with whether or not these
results could be repeated! I've been trying to duplicate the results of a
combo of red iron oxide stain that touched (just touched) some thirsty green
soil, both painted on the already-fired majolica at the same time. Fired at
^06. The Thirsty Green ran into the RIO areas and made a wonderful pattern
and crystallization (even at ^06). Can't get it to happen again. (Sigh) I
have one sloppy-handled cup used for a test that came out like a dream.
Can't show the cup in public but I can dream on it!
Do we all have some nice surprise we can't repeat?
Michele Williams
Margaret Barlow on sat 4 may 02
Hi Marianne,
It sounds to me like you have primary crazing on the three mugs, this means
it will not take much to fix the glaze. The reason it did not craze on the
mug that was wet was because this caused the glaze application to be
thinner. A glaze that is thinner is not under as much tension as a thicker
one. However all 4 mugs may have further crazing in time.
Also because of the thinner application the fourth mug did not run as much.
The fact that the glaze has a low viscosity (is fluid) is a bonus if you
want to eliminate the crazing, as it means you can simply increase the
silica and alumina. This will reduce the high expansion which is the cause
of the crazing, and make the glaze more viscous (less fluid) thereby killing
two birds with one stone.
If you would like me to adjust the recipe for you, send me the recipe and I
will put it on INSIGHT and reduce the expansion, then you can test the new
glaze.
Margaret
-----Original Message-----
From: Marianne Lombardo
To: CLAYART@LSV.CERAMICS.ORG
Date: Saturday, May 04, 2002 11:49 AM
Subject: Set of Mugs One Didn't Craze
Generally I brush on my glazes, but I like the Red Gold so much on the
outside of vessels that I made up a small bucketful and decided to try my
hand at dipping the mugs into the glaze.
The first mug slipped out of my fingers and fell right into the bucket. So
I took it over to the sink and had to scrub quite a while to get all the
glaze off and try again. On that mug the next morning the glaze was still
wet looking and took a long time to dry.
The claybody was Tucker's MCS porcelain ^6. When I placed the set in the
kiln I noted the position on the shelf that I placed that particular mug.
Now this is really odd. The other 3 mugs, the creamer and sugar bowl all
crazed. Big long craze lines spaced about 1/2 inch apart. No big deal, I
thought it might on porcelain but was willing to take a chance. The odd
thing is the mug that was overly wet and took forever to dry, did not craze.
Not a bit. And, it was the *only* piece of the set that the glaze did not
run right off onto the shelf. At the bottom the glaze pooled and set and
held in the indentation I make in the foot, but only on that one mug.
The only variables with that one mug are that it was very wet when I glazed
it, and it was placed a bit closer to an element than the others.
I also applied two other glazes on the rims, but the application was
consistent with all pieces.
Only this one mug will give off a nice musical pingggg when I flick it with
my finger.
Marianne Lombardo
Omemee, Ontario, Canada
____________________________________________________________________________
__
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.
Marianne Lombardo on sun 5 may 02
Thanks to all of you that replied about this. I don't really know why I =
didn't see the answer myself. Too close to the problem, I guess. The =
glaze must have gone on much thinner on this particular mug.
However, this morning when I looked at the mug, it has now crazed. So =
obviously, this glaze doesn't fit the clay.
Marianne Lombardo
Omemee, Ontario, Canada
Ron Roy on mon 6 may 02
Easy Marianne,
The glaze is just crazing (easy to fix) and the wet mug got a thinner glaze
coat. One of the rules - when you are working with ceratain glazes is -
don't get it on too thick or it will craze. It must have to do with the
thinner coating getting enough silica from the clay to lower the expansion
(of a glaze only just crazing) just enogh to srop it.
Don't be surprised if the glaze does craze over time - can happen.
RR
>The first mug slipped out of my fingers and fell right into the bucket.
>So I took it over to the sink and had to scrub quite a while to get all
>the glaze off and try again. On that mug the next morning the glaze was
>still wet looking and took a long time to dry.
>
>The claybody was Tucker's MCS porcelain ^6. When I placed the set in the
>kiln I noted the position on the shelf that I placed that particular mug.
>
>Now this is really odd. The other 3 mugs, the creamer and sugar bowl all
>crazed. Big long craze lines spaced about 1/2 inch apart. No big deal, I
>thought it might on porcelain but was willing to take a chance. The odd
>thing is the mug that was overly wet and took forever to dry, did not
>craze. Not a bit. And, it was the *only* piece of the set that the glaze
>did not run right off onto the shelf. At the bottom the glaze pooled and
>set and held in the indentation I make in the foot, but only on that one
>mug.
>
>The only variables with that one mug are that it was very wet when I
>glazed it, and it was placed a bit closer to an element than the others.
>
>I also applied two other glazes on the rims, but the application was
>consistent with all pieces.
>
>Only this one mug will give off a nice musical pingggg when I flick it
>with my finger.
>
>Marianne Lombardo
>Omemee, Ontario, Canada
Ron Roy
RR #4
15084 Little Lake Road
Brighton
Ontario
Canada - K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
| |
|
