Mike Barber on fri 6 jul 07
Hi all. This is my first post, though I have been learning much by
reading. I am currently working with cone 6 glazes and have been
using the mastering cone 6 glazes from "the book". This question
regards the Semi matte slate blue.
On speckled brownstone clay from Highwater I have an odd phenomenon:
the inside of the vessel (bowls particularly) is a great blue color.
On the ouside it is a green (still pretty nice). The issue is that the
glaze
appears VERY thin on the outside. The obvious answer is that I am
applying it too thin, but I don't see what I would be doing wrong. I
dip the entire piece for varying lengths of time,
usually 3 seconds. I have tried longer and I have dipped multiple
times. The glaze appears to me to be the same thickness before I fire. But
everytime I unload the kiln I have denim blue on the inside and a
sage type green on the outside. I have little pinholes on the outside
and seems like it is very thin. It isn't running off the pot.
So, does anyone have an idea? This does not happen on Little Loafers,
and all the other glazes are the same inside and out. It is only the
slate blue on the speckled brownstone.
As a side note: Thank you to John and Ron. Your book has saved me
tons of trouble and time and given me a good starting point as a
beginner.
-Mike Barber
Lee Love on sat 7 jul 07
On 7/7/07, Michael Wendt wrote:
> In this case, try glazing the inside one day,
> let it dry, then glaze the outside the next day.
> If this solves the problem, then that is
> the probable cause.
My thought was to glaze the outside first, the side that seems to be
thin. You can dip lip first and then pour on the inside after the
outside is dry.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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
Michael Wendt on sat 7 jul 07
Mike,
This can happen when the piece is fairly thin,
because it can't absorb enough water from
the glaze before it is saturated.
I am surprised that the outside is thin.
Usually for me, the inside is harder to
get even.
In this case, try glazing the inside one day,
let it dry, then glaze the outside the next day.
If this solves the problem, then that is
the probable cause.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Mike wrote:
On speckled brownstone clay from Highwater I have an
odd phenomenon:
the inside of the vessel (bowls particularly) is a
great blue color.
On the outside it is a green (still pretty nice). The
issue is that the
glaze
appears VERY thin on the outside. The obvious answer is
that I am
applying it too thin, but I don't see what I would be
doing wrong. I
dip the entire piece for varying lengths of time,
usually 3 seconds. I have tried longer and I have
dipped multiple
times. The glaze appears to me to be the same thickness
before I fire. But
everytime I unload the kiln I have denim blue on the
inside and a
sage type green on the outside. I have little pinholes
on the outside
and seems like it is very thin. It isn't running off
the pot.
claystevslat on sun 8 jul 07
Mike --
Everyone's approach is different, and it's hard to say
whaat's causing the problem here -- but if thickness is
the issue, and you have been glazing the inside first and
then the outside, you may do better by doing the outside first,
then the inside, (especially if you dip and pour). The reason
is that the first application of glaze adds moisture to the
walls of the pot, which can reduce the amount of glaze
absorbed in the second application -- but it's easy to
get a good coat on the inside (just leave it in and roll it
around a bit more before dumping it out).
Just an idea, there may be other issues at play.
Regards -- Steve S
--- In clayart@yahoogroups.com, Mike Barber wrote:
>
> Hi all. This is my first post, though I have been learning much by
> reading. I am currently working with cone 6 glazes and have been
> using the mastering cone 6 glazes from "the book". This question
> regards the Semi matte slate blue.
>
> On speckled brownstone clay from Highwater I have an odd
phenomenon:
> the inside of the vessel (bowls particularly) is a great blue
color.
> On the ouside it is a green (still pretty nice). The issue is that
the
> glaze
> appears VERY thin on the outside. The obvious answer is that I am
> applying it too thin, but I don't see what I would be doing wrong.
I
> dip the entire piece for varying lengths of time,
> usually 3 seconds. I have tried longer and I have dipped multiple
> times. The glaze appears to me to be the same thickness before I
fire. But
> everytime I unload the kiln I have denim blue on the inside and a
> sage type green on the outside. I have little pinholes on the
outside
> and seems like it is very thin. It isn't running off the pot.
>
> So, does anyone have an idea? This does not happen on Little
Loafers,
> and all the other glazes are the same inside and out. It is only
the
> slate blue on the speckled brownstone.
>
> As a side note: Thank you to John and Ron. Your book has saved me
> tons of trouble and time and given me a good starting point as a
> beginner.
>
> -Mike Barber
>
>
_____________________________________________________________________
_________
> Send postings to clayart@...
>
> 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@...
>
Michael Wendt on sun 8 jul 07
Perhaps a little explanation is in order as to why
we glaze the inside first and let it dry.
I have invented a bowl glazer that is easy.
(See http://www.wendtpottery.com/supply.htm
for a view of the large bowl glazing system I use.)
By glazing the inside first, the rim can be waxed
after the inside application of glaze. The outside
drips and runs can be washed off to the wax line
with cold water. The next day, the bowl is placed
upside down on the bowl glazer and the outside is
poured perfectly. This results in a flawless glaze
surface. You can even use two different glazes,
one on the inside and one on the outside and have
them form a sharp line where they meet for a very
striking effect. Also. no oversplashing onto dry
glaze surfaces occurs.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Lee wrote:
My thought was to glaze the outside first, the side
that seems to be
thin. You can dip lip first and then pour on the
inside after the
outside is dry.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
Jonathan Kirkendall on sun 8 jul 07
Hi Mike,
I find this sort of stuff fascinating. There could be at least a couple
of issues here.
First, as you note, glaze thickness could be a problem and I think the
first place I would start. If you're dipping, the inside of bowls
almost always gets a slightly thicker coat of glaze. If you think about
it, when you dip a bowl and bring it up out of the glaze, the glaze on
the sides runs off back into the bucket while the glaze inside
goes...nowhere, until a second or two later you pour it out. I've
gotten to the point where I twist the bowl inside the glaze bucket and
take it out upside down - I get a more even coat that way. Of course,
that's harder to do with larger pieces; I now glaze the inside of a
large bowl and then I turn the bowl upside down and pour the glaze over
the outside.
But there is something else, too. I think that in a firing, the inside
of pieces face a slightly different, cooler, atmosphere. I've had very
temperature sensitive glazes that looked fine on the inside of a bowl
but blistered on the outside. I've also seen this with bowls where the
glaze will be shiny on the outside and more matte inside. Also, I have
a high copper glaze that DOES turn a muddy red on the inside (this is
NOT for functional pieces), which makes me wonder if there is some sort
of very slight reduction atmosphere happening - or something.
Good luck!
Jonathan in DC
Mike Barber wrote:
> Hi all. This is my first post, though I have been learning much by
> reading. I am currently working with cone 6 glazes and have been
> using the mastering cone 6 glazes from "the book". This question
> regards the Semi matte slate blue.
>
> On speckled brownstone clay from Highwater I have an odd phenomenon:
> the inside of the vessel (bowls particularly) is a great blue color.
> On the ouside it is a green (still pretty nice). The issue is that the
> glaze
> appears VERY thin on the outside. The obvious answer is that I am
> applying it too thin, but I don't see what I would be doing wrong. I
> dip the entire piece for varying lengths of time,
> usually 3 seconds. I have tried longer and I have dipped multiple
> times. The glaze appears to me to be the same thickness before I fire. But
> everytime I unload the kiln I have denim blue on the inside and a
> sage type green on the outside. I have little pinholes on the outside
> and seems like it is very thin. It isn't running off the pot.
>
> So, does anyone have an idea? This does not happen on Little Loafers,
> and all the other glazes are the same inside and out. It is only the
> slate blue on the speckled brownstone.
>
> As a side note: Thank you to John and Ron. Your book has saved me
> tons of trouble and time and given me a good starting point as a
> beginner.
>
> -Mike Barber
>
> ______________________________________________________________________________
> 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 sun 8 jul 07
On 7/8/07, Jonathan Kirkendall wrote:
>
> But there is something else, too. I think that in a firing, the inside
> of pieces face a slightly different, cooler, atmosphere. I've had very
> temperature sensitive glazes that looked fine on the inside of a bowl
> but blistered on the outside. I've also seen this with bowls where the
> glaze will be shiny on the outside and more matte inside.
Pots reduce more on the inside than the outside.
To keep glaze from being thicker on the inside I do something
Like Jonathan: with a small bowl, you hold lip and foot, thumb on
the lip, middle finger on the foot. You swish the bowl when it is in
the glaze and when you take it out, you hold it lip down, while making
circles as the wet glaze drips out in a circle at the lip. Only
after it stops running, do you flip it right side up to set down.
Then you touch up the print at the lip with a dab of glaze off your
finger.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.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
Mike Barber on mon 9 jul 07
Roy,
I'm not sure this really answers the question, but I use roughly 900ml of
water for every 1000g of dry glaze. Maybe 950. And it didn't occur to me
until answering your question, but I don't do anything to check the
thickness of the glaze each time I use it. I just get the bucket out, stir
it up and have at it! I bisque fire using the built in computer program
(I use your published program for glaze), but did notice that the witness
cone indicated that it wasn't In my last bisque I only had an 04 cone in
and it was starting to bend, but clearly not fully fired.
I mentioned in my original post that part of my puzzlement was that this
glaze didn't do that on Little Loafers clay. Well, I used that clay for a
few kiln loads, then I started using Speckled Brownstone. Is is possible
that it isn't a difference in the clay at all, but rather a thinning of
the glaze as it has been used? Does this happen?
All,
Thanks very much for all the responses.
-Mike
Ron Roy on mon 9 jul 07
Hi Mike - thanks for the good words about our book!
What cone are you firing your bisque to and are you using cones?
How thick is clay you are glazing?
Could it be your glaze is too thin in the bucket?
RR
>Hi all. This is my first post, though I have been learning much by
>reading. I am currently working with cone 6 glazes and have been
>using the mastering cone 6 glazes from "the book". This question
>regards the Semi matte slate blue.
>
>On speckled brownstone clay from Highwater I have an odd phenomenon:
>the inside of the vessel (bowls particularly) is a great blue color.
>On the ouside it is a green (still pretty nice). The issue is that the
>glaze
>appears VERY thin on the outside. The obvious answer is that I am
>applying it too thin, but I don't see what I would be doing wrong. I
>dip the entire piece for varying lengths of time,
>usually 3 seconds. I have tried longer and I have dipped multiple
>times. The glaze appears to me to be the same thickness before I fire. But
>everytime I unload the kiln I have denim blue on the inside and a
>sage type green on the outside. I have little pinholes on the outside
>and seems like it is very thin. It isn't running off the pot.
>
>So, does anyone have an idea? This does not happen on Little Loafers,
>and all the other glazes are the same inside and out. It is only the
>slate blue on the speckled brownstone.
>
>As a side note: Thank you to John and Ron. Your book has saved me
>tons of trouble and time and given me a good starting point as a
>beginner.
>
>-Mike Barber
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
John Sankey on mon 9 jul 07
There is another advantage to glazing the inside first to those already
mentioned - if you slop or overfill with the inside glaze, you get a
chance to clean up the outside before you glaze it!
--
(Add 'Byrd' to the subject line of your reply to get through my spam filter)
Mike Barber on tue 10 jul 07
>Roy,
>I'm not sure this really answers the question...
Uh, that's Mr. Roy! Sorry Ron!!
Donna Kat on tue 10 jul 07
On Sun, 8 Jul 2007 09:17:53 -0400, Jonathan Kirkendall
wrote:
>But there is something else, too. I think that in a firing, the inside
>of pieces face a slightly different, cooler, atmosphere. I've had very
>temperature sensitive glazes that looked fine on the inside of a bowl
>but blistered on the outside. I've also seen this with bowls where the
>glaze will be shiny on the outside and more matte inside. Also, I have
>a high copper glaze that DOES turn a muddy red on the inside (this is
>NOT for functional pieces), which makes me wonder if there is some sort
>of very slight reduction atmosphere happening - or something.
From how Randy's (Toby's) Red acts I would guess that the inside of a bowl
or cup cools slower than the outside or a plate. Even when I am certain
that the thickness is the same on the inside and out, the inside with
Randy's is that red you try to get while the outside is more brown.
I'm amazed you are getting red out of a copper glaze with an electric kiln
(even if it is that liver yuck...). May I ask what your ingredients are?
Donna
Jennifer Boyer on wed 11 jul 07
I think I'd stick with the concept that the first glaze application
on the inside is saturating the clay wall, preventing a thick coat
when you dip the outside. It could be that the other clay you were
using got harder at your bisk temp so this effect didn't show so
much, but that your new clay is a softer bisk and sucks up the water
from the inside glaze more aggressively. Let those pots dry out
before you glaze the outside. You can get pretty good at gauging
dryness by touching the pots and feeling how cool they are. Coolness
= Wetness. Touch an unglazed pot and try to let the 1/2 glazed pot
sit around til it feels like that.
Jennifer
On Jul 10, 2007, at 12:03 AM, Mike Barber wrote:
> Roy,
> I'm not sure this really answers the question, but I use roughly
> 900ml of
> water for every 1000g of dry glaze. Maybe 950. And it didn't occur
> to me
> until answering your question, but I don't do anything to check the
> thickness of the glaze each time I use it. I just get the bucket
> out, stir
> it up and have at it! I bisque fire using the built in computer
> program
> (I use your published program for glaze), but did notice that the
> witness
> cone indicated that it wasn't In my last bisque I only had an 04
> cone in
> and it was starting to bend, but clearly not fully fired.
>
> I mentioned in my original post that part of my puzzlement was that
> this
> glaze didn't do that on Little Loafers clay. Well, I used that clay
> for a
> few kiln loads, then I started using Speckled Brownstone. Is is
> possible
> that it isn't a difference in the clay at all, but rather a
> thinning of
> the glaze as it has been used? Does this happen?
>
> All,
> Thanks very much for all the responses.
>
> -Mike
>
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Mike Barber on sat 28 jul 07
On Fri, 6 Jul 2007 22:42:51 -0500, Mike Barber
wrote:
>Hi all. This is my first post, though I have been learning much by
>reading. I am currently working with cone 6 glazes and have been
>using the mastering cone 6 glazes from "the book". This question
>regards the Semi matte slate blue.
>
>On speckled brownstone clay from Highwater I have an odd phenomenon:
>the inside of the vessel (bowls particularly) is a great blue color.
>On the ouside it is a green (still pretty nice). The issue is that the
>glaze
>appears VERY thin on the outside. The obvious answer is that I am
>applying it too thin, but I don't see what I would be doing wrong. I
>dip the entire piece for varying lengths of time,
>usually 3 seconds. I have tried longer and I have dipped multiple
>times. The glaze appears to me to be the same thickness before I fire. But
>everytime I unload the kiln I have denim blue on the inside and a
>sage type green on the outside. I have little pinholes on the outside
>and seems like it is very thin. It isn't running off the pot.
>
>So, does anyone have an idea? This does not happen on Little Loafers,
>and all the other glazes are the same inside and out. It is only the
>slate blue on the speckled brownstone.
>
>As a side note: Thank you to John and Ron. Your book has saved me
>tons of trouble and time and given me a good starting point as a
>beginner.
>
>-Mike Barber
>
>__________________________________________________________________________
____
>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.
To All,
Thanks for all the suggestions. I thought I would report back on my
findings so far. It appears that the glaze was just too thin in the
bucket - as RR suggested. Before glazing last I skimmed water off the top
before mixing the glaze again. Now I am getting very similar results
inside and out.
Thanks again.
Mike Barber
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