Jim and Marge Wade on tue 27 mar 01
Can someone answer this question for me? I just picked up a porcelain bowl
that I high fired to ^10 at a local clay center. The amber celadon glaze I
put on it ran totally down the bowl and onto the shelf, even though the
entire foot (5/8" as it was a nice sized bowl) was wiped clean. Originally I
was intending to soda fire this piece with only a flashing slip on the
exterior, so I had lightly sanded portions of the exterior with a green
scrubby at the greenware stage to remove a few fingerprints (which my
instructor suggested the class do with our porcelain pieces). I did not sand
the whole bowl, just where there were a few irregularities. I am not one to
sand my pots anyway due to the health issues. However, as the bowl was not
bone dry, I thought I'd try it. I asked the woman who runs the studio (I was
honest and admitted to her that I was the one that caused the huge gouge in
the kiln shelf!) what might have caused this. She asked if I had sanded the
bowl (she had heard my instructor talking about) explaining that sanding
causes compressed surface on the pots, making it difficult for glazes to
adhere. I discussed all this with my instructor and she asked me to run this
whole idea about glazes running due to sanded pots by Clayart. My instructor
does not talk about sanding anything other than porcelain to be soda fired,
where glazing the exterior is often kept to a minimum.
Anyway, now I have a beautiful bowl that will have to be buried in the
garden with some water in it for the birds. The foot is so messed up
grinding isn't even an option.
Thanks for your input.
Marge
Jocelyn McAuley on tue 27 mar 01
Hi Marge,
Did you wash your piece after sanding the surface? It's possible that
the dusty surface of your piece caused the glaze to not adhere well to
your pot. I've had this happen with the dusty interior (thank
goodness!) of a piece. The glaze completely crawled off in sheets- and
the glaze was normally a well behaved celedon.
That's my idea. The compression of the surface theory is interesting- do
burnished pieces cause glaze to run off? I don't know.
Good luck
--
Jocelyn McAuley ><<'> jocie@worlddomination.net
Jay Jensen on wed 28 mar 01
Whenever someone asks why did the glaze run? I say one
thing. Have you ever used that glaze before?
You have to experiment first with application, clay
bodies and temp. At the Northern Clay Center where I
teach the amber celadon when put on thick and fired to
a strong cone 10 is a runner but again there a million
amber celadon recipes too.
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Wade Blocker on wed 28 mar 01
Marge, I assume that you sanded the piece before it was bisqued, then
glazed it for the glaze firing. If the glaze ran at that point it had
nothing to do with your sanding. The glaze was either not a cone 10 glaze,
or it was applied too heavily. Mia in ABQ
Jim and Marge Wade on wed 28 mar 01
Jay,
Actually it WAS at Northern Clay Center!! No, I had not used that glaze on
porcelain before. I must have been too thick. Maybe I'll run into you at NCC
and talk more about it.
Marge
> From: Jay Jensen
> Reply-To: Ceramic Arts Discussion List
> Date: Wed, 28 Mar 2001 08:08:46 -0800
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Running glaze
>
> Whenever someone asks why did the glaze run? I say one
> thing. Have you ever used that glaze before?
> You have to experiment first with application, clay
> bodies and temp. At the Northern Clay Center where I
> teach the amber celadon when put on thick and fired to
> a strong cone 10 is a runner but again there a million
> amber celadon recipes too.
>
>
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Jay Jensen on thu 29 mar 01
What do you mean when you were there? At the NCC. If
they are using the same temmoku I hate it!!!!
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Lee Love on thu 29 mar 01
----- Original Message -----
From: "Jim and Marge Wade"
: Actually it WAS at Northern Clay Center!!
from: Jay Jensen
: > bodies and temp. At the Northern Clay Center where I
: > teach the amber celadon when put on thick and fired to
: > a strong cone 10 is a runner but again there a million
: > amber celadon recipes too.
I tried to get them to change the temmoku and celadon when I was there,
because it is Leach's 1234 with Iron added. The 1234 begins as a cone 8
glaze and Leach says if you add iron, to add .5% kaolin for every % of iron
added. You'd have to add about 4.5% kaolin to the temmoku make it a cone 8
glaze and .5% to the celadon to make it cone 8.
Another change that could be made is to use all or part kaolin instead
of ball clay.
--
Lee Love
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Jay Jensen on thu 29 mar 01
Yes look me up. Will not teach until June.
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Jay Jensen on thu 29 mar 01
I was going to mention about the sanding. I have never
heard of this phenominon, then again why
the hell would you sand your pots, there nothing I
like better than the marks made on clay when throwing.
Anyway even at bone dry how could you change surface tension.
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kilnboy on thu 29 mar 01
Howdy folks,
New to this list, but thought I'd jump right in. As to glazes running on
sanded clay; I've sanded some pieces in the past, and to keep glazes from
crawling or running, I lightly brush clean water over the sanded surface
before bisque firing to glue down any loose particles, as sanding creates a
layer of dust that can lead to crawling or slipping.
best,
CJ
> From: Jim and Marge Wade
> To: CLAYART@LSV.CERAMICS.ORG
> Date: Wednesday, March 28, 2001 12:38 AM
> Subject: Running glaze
>
>
> >Can someone answer this question for me? I just picked up a porcelain
bowl
> >that I high fired to ^10 at a local clay center. The amber celadon glaze
I
> >put on it ran totally down the bowl and onto the shelf, even though the
> >entire foot (5/8" as it was a nice sized bowl) was wiped clean.
Originally
> I
> >was intending to soda fire this piece with only a flashing slip on the
> >exterior, so I had lightly sanded portions of the exterior with a green
> >scrubby at the greenware stage to remove a few fingerprints (which my
> >instructor suggested the class do with our porcelain pieces).
Jim and Marge Wade on thu 29 mar 01
Does that include porcelain? What about the marks made while taking a
porcelain pot off the wheel, or if (as can happen in shared studio space)
someone else accidentally bumps into one of your pots? I was told by my
instructor that porcelain shows everything, especially in a soda firing, so
smooth up any imperfections. Prior to this I never considered sanding. In
general I feel that pots should show the marks of throwing. Pots that speak
to me show that they have been made by hand. I guess if I wanted "perfect"
pots I could always go to Target and buy them.
Marge
> From: Jay Jensen
> Reply-To: Ceramic Arts Discussion List
> Date: Thu, 29 Mar 2001 05:41:12 -0800
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Running glaze
>
> I was going to mention about the sanding. I have never
> heard of this phenominon, then again why
> the hell would you sand your pots, there nothing I
> like better than the marks made on clay when throwing.
>
> Anyway even at bone dry how could you change surface tension.
>
> __________________________________________________
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> Get email at your own domain with Yahoo! Mail.
> http://personal.mail.yahoo.com/?.refer=text
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> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
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> settings from http://www.ceramics.org/clayart/
>
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> melpots@pclink.com.
norman cohen on sun 3 feb 02
clayarters: my green (cone 5) is a lovely transparent color - picks up =
all bisque markings, BUT runs like hell. do you have a recommendation =
for tightening up this sucker? norm
Paul Lewing on sun 3 feb 02
on 2/3/02 8:14 AM, norman cohen at norco1@DELLEPRO.COM wrote:
> clayarters: my green (cone 5) is a lovely transparent color - picks up =
> all bisque markings, BUT runs like hell. do you have a recommendation =
> for tightening up this sucker? norm
Norm, you can usually solve the running by adding more clay, but to tell you
for sure, we need the recipe.
Paul Lewing, Seattle
ronnie beezer on thu 27 jan 05
Hello everyone:
I need your help.I would like to know if there is anything I could add to a glaze to minimize the running. I have this beautiful combination of two glazes that I purchased from two different sources. The glazes are fired to 6^.It ran so much that not only the pot got ruined but also the shelf. I have used this combination before on a platter and it came out great. This particular piece was a tall vase. I applied the glaze the same way on both pieces.
Thank you,
Ronnie
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Daniel Semler on sat 29 jan 05
Hi Ronnie,
I've been thinking about how to approach this. Here is a dump of my current
thoughts. Hopefully its some use.
I don't know how you are using the two glazes. Are you mixing them in some
proportion to produce a new single glaze or, are you layering the two ? What
are the individual glazes like at cone 6 ? Are they stiff, fluid etc. ?
If you are layering, then thickness of application may go a long way toward
solving the problem, as would not overlapping too near the bottom of tall
vertical pieces. Of course this may not generate the exact effect you're after.
If you are mixing them (and perhaps even if you are not) you may want to
stiffen the glaze (or one of them). Without the recipe this is a trial and
error exercise. It too is likely to result in a difference in the finished
glaze to a greater or lesser extent. If you wanted to play with this, then I'd
probably start trying to line blend in alumina and see how much is required to
prevent excessive running, consistent with the final result you want. I'd
probably try a blend from 2 to say 20% alumina by dry weight. Do you get the
glazes dry or wet ? If wet, you'll need Brogniart's formula to help out a bit,
or you could just take a guess - just keep notes of what volume of glaze and
what weight of alumina.
The other choice is firing. It sounds like the glazes in combination are very
runny, perhaps indicating either a lower final temp, or shorter soak (if you
have one) would be good. Are these fritted glazes ? I vaguely recall that such
glazes can have a fairly short firing range.
Whatever you do will require a bit of experimentation and notes will help. If
you stiffen the glazes, you will then have to hope they don't monkey with the
formulae in the future.
Finally, have you tried getting assistance from either manufacturer concerning
their own product.
Thanx
D
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