Dave Finkelnburg on tue 2 jan 07
John, Beth,
Dr. William Carty at Alfred claims firing
dehydroxylates kaolin (drives the water off it). As a
result, he says, the fired surface of the clay is
somewhat hydrophobic (repels water). Dipping the ware
in water, sponging it, etc permits the clay to attach
itself to some water (rehydroxylates the clay) and
renders the surface hydrophyllic again (attracts
water). As a result, the surface is less prone to
glaze faults.
I do not know whether his statements are accurate.
I have never read this in the published literature.
I have not tested it personally. There are other
variables, like glaze composition, surface roughness
of the ware, dust, etc. which would make a test
difficult. I have found Carty to be a credible source
of such information, given that his Ph.D. is in
surface chemistry and he has worked quite a bit with
clay products, but I'm biased because he was my MS
advisor.
Good glazing,
Dave Finkelnburg
--- John Hesselberth
wrote:
> > On Jan 2, 2007, at 11:40 AM, Beth Spindler wrote:
> > Am I missing a step or what? I have never rinsed
> >bisque ware from the kiln. Do I need to rinse???
> Hi Beth,
My gut tells me this is one of the potters' legends
> that won't hold up to serious testing.
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Beth Spindler on tue 2 jan 07
Am I missing a step or what? I have never rinsed bisque ware from the kiln. I just take a soft brush and dust off the residue from firing before I glaze it. Do I need to rinse???
Beth in VA
No snow yet in Charlottesville, VA.......and my daughter is now in Vermont on a ski trip and I see where the temps are in the high 30's and low 40's....go figure.....any time of the year is a good time for Vermont though.... :)
-----Original Message-----
From: relax@MOLEY.UK.COM
To: CLAYART@LSV.CERAMICS.ORG
Sent: Tue, 2 Jan 2007 9:16 AM
Subject: Bisque ware turns yellow
Dear Barry,
when just out of the kiln it is totally dry and so seemingly white, when water
is taken in it shows its true colour. When bisque sits around it absorbs the
ambient moisture and will become a darker hue from kiln fresh ware, so unless
your water is saturated with iron oxide etc it should not "colour" the ware.
Happy potting Marek
Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
Fully Residential Pottery Courses and more at Mole Cottage www.moleys.com
"Tips and Time Travel from a Vernacular Potter" reviews on www.keramix.com
an irreverent point of view after 35 years in the game Marek Drzazga-Donaldson
Assemble a dragon finial at www.dragonfinials.co.uk
Free Works and Mole Cottage DVD's and Video content on all the sites
Drzazga Video Promotions at www.drzazga.co.uk Submit address for DVD
______________________________________________________________________________
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Jonathan Kirkendall on tue 2 jan 07
Hi Beth,
It's not necessary - I never did it until I moved to Colorado and
started throwing in dusty dry Boulder where a lot of the potters rinsed
bisqueware. Now, in damp DC (oops, I typed damn DC by mistake first!),
if I have time, I'll rinse as I take it out of the kiln, let it sit
overnight, and glaze the next day. But if I'm in a hurry, I don't. I
find it difficult to say empirically how it helps, but I do find that
when I rinse, my glazes seem to go on better (I dip) - more evenly, with
more consistent application. Maybe some others can say better why they
do it (I mean, something other than "because that's the way I've always
done it").
You might want to try it and see.
Jonathan in DC
Beth Spindler wrote:
> Am I missing a step or what? I have never rinsed bisque ware from the kiln. I just take a soft brush and dust off the residue from firing before I glaze it. Do I need to rinse???
> Beth in VA
>
> No snow yet in Charlottesville, VA.......and my daughter is now in Vermont on a ski trip and I see where the temps are in the high 30's and low 40's....go figure.....any time of the year is a good time for Vermont though.... :)
>
>
> -----Original Message-----
> From: relax@MOLEY.UK.COM
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Tue, 2 Jan 2007 9:16 AM
> Subject: Bisque ware turns yellow
>
>
> Dear Barry,
>
> when just out of the kiln it is totally dry and so seemingly white, when water
> is taken in it shows its true colour. When bisque sits around it absorbs the
> ambient moisture and will become a darker hue from kiln fresh ware, so unless
> your water is saturated with iron oxide etc it should not "colour" the ware.
>
> Happy potting Marek
>
>
>
> Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
> Fully Residential Pottery Courses and more at Mole Cottage www.moleys.com
> "Tips and Time Travel from a Vernacular Potter" reviews on www.keramix.com
> an irreverent point of view after 35 years in the game Marek Drzazga-Donaldson
>
> Assemble a dragon finial at www.dragonfinials.co.uk
> Free Works and Mole Cottage DVD's and Video content on all the sites
> Drzazga Video Promotions at www.drzazga.co.uk Submit address for DVD
>
> ______________________________________________________________________________
> 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.
> ________________________________________________________________________
> Check out the new AOL. Most comprehensive set of free safety and security tools, free access to millions of high-quality videos from across the web, free AOL Mail and more.
>
> ______________________________________________________________________________
> 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.
>
>
>
Victoria E. Hamilton on tue 2 jan 07
Hello all -
Rather than rinsing (full immersion?), I dust bisqued pieces with a damp
sponge which I constantly wring out in clean water. I do this (and teach
this) because bisqueware just out of the kiln is covered with ceramic dust,
or if it has been sitting around for a while it may be covered with studio
dust, grime, scum, etc. and any of this can inhibit the ability of the ware
to properly absorb glazes.
Just another take on it. Hope this helps.
Vicki Hamilton
Millennia Antica Pottery
Seattle, WA, where it nasty today - buckets of rain, high winds.....oh joy!
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Jonathan
Kirkendall
Sent: Tuesday, January 02, 2007 11:19 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: [CLAYART] Bisque ware turns yellow- Rinsing???????
Hi Beth,
It's not necessary - I never did it until I moved to Colorado and started
throwing in dusty dry Boulder where a lot of the potters rinsed bisqueware.
Now, in damp DC (oops, I typed damn DC by mistake first!), if I have time,
I'll rinse as I take it out of the kiln, let it sit overnight, and glaze the
next day. But if I'm in a hurry, I don't. I find it difficult to say
empirically how it helps, but I do find that when I rinse, my glazes seem to
go on better (I dip) - more evenly, with more consistent application. Maybe
some others can say better why they do it (I mean, something other than
"because that's the way I've always done it").
You might want to try it and see.
Jonathan in DC
Beth Spindler wrote:
> Am I missing a step or what? I have never rinsed bisque ware from the
kiln. I just take a soft brush and dust off the residue from firing before
I glaze it. Do I need to rinse???
> Beth in VA
>
> No snow yet in Charlottesville, VA.......and my daughter is now in
> Vermont on a ski trip and I see where the temps are in the high 30's
> and low 40's....go figure.....any time of the year is a good time for
> Vermont though.... :)
>
>
> -----Original Message-----
> From: relax@MOLEY.UK.COM
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Tue, 2 Jan 2007 9:16 AM
> Subject: Bisque ware turns yellow
>
>
> Dear Barry,
>
> when just out of the kiln it is totally dry and so seemingly white,
> when water is taken in it shows its true colour. When bisque sits
> around it absorbs the ambient moisture and will become a darker hue
> from kiln fresh ware, so unless your water is saturated with iron oxide
etc it should not "colour" the ware.
>
> Happy potting Marek
>
>
>
> Hand made Architectural Ceramics from No9 Studio UK www.no9uk.com
> Fully Residential Pottery Courses and more at Mole Cottage
> www.moleys.com "Tips and Time Travel from a Vernacular Potter" reviews
> on www.keramix.com an irreverent point of view after 35 years in the
> game Marek Drzazga-Donaldson
>
> Assemble a dragon finial at www.dragonfinials.co.uk Free Works and
> Mole Cottage DVD's and Video content on all the sites Drzazga Video
> Promotions at www.drzazga.co.uk Submit address for DVD
>
> ______________________________________________________________________
> ________ 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.
> ______________________________________________________________________
> __ Check out the new AOL. Most comprehensive set of free safety and
> security tools, free access to millions of high-quality videos from across
the web, free AOL Mail and more.
>
> ______________________________________________________________________
> ________ 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 postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
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Moderator of the list is Mel Jacobson who may be reached at
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John Hesselberth on tue 2 jan 07
On Jan 2, 2007, at 11:40 AM, Beth Spindler wrote:
> Am I missing a step or what? I have never rinsed bisque ware from
> the kiln. I just take a soft brush and dust off the residue from
> firing before I glaze it. Do I need to rinse???
> Beth in VA
Hi Beth,
Not in my opinion, you don't need to rinse. Some pottery teachers,
though, teach their students to do it regularly. They think it helps
discourage pinholes. I suppose it might if a piece is extremely
dusty. I do occasionally use a barely lamp sponge to dust a piece if
it has been sitting around for several weeks after bisque firing.
Rinsing can certainly cause some problems with non-uniform glaze
pickup unless the pieces are thoroughly dried after rinsing. That
would take several days at room temperature unless you live in an
arid climate.
My gut tells me this is one of the potters' legends that won't hold
up to serious testing. But, hey, if what you are doing works for you
keep on doing it. And if you lose a lot of pots due to pinholes it
might be worth a try.
Regards,
John
Lee Love on wed 3 jan 07
On 1/3/07, John Hesselberth wrote:
> On Jan 2, 2007, at 11:40 AM, Beth Spindler wrote:
> Hi Beth,
>
> Not in my opinion, you don't need to rinse. Some pottery teachers,
> though, teach their students to do it regularly. They think it helps
> discourage pinholes. I suppose it might if a piece is extremely
> dusty.
Here in Mashiko, the bisque is at a much lower temp:n 750 to
850*C. When a bisque is soft, if you don't sponge you get pinholing
from the air leaving the bisque when the glaze is applied.. Even if
you dust, you will still get pinholing.
The advantage of a soft bisque and sponging, is that you
can control glazes thickness by the amount of water you use to sponge
with.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Kathy McDonald on wed 3 jan 07
I always find that a good dunk in clear warm water
and then allowing pieces to dry for a few hours
lessens pinholes, particularly in rutile glazes.
If I am rushed and forget, or don't let the pieces dry
well enough application issues are a problem.(ie:glaze
is too thin)
When I had my work area on a farm where the water was "hard"
I often had the porcelain bisque turn yellow. I sometimes
even blamed
the cats it was so pronounced. The farm cats roamed freely
around the
area.
Doesn't seem to be an issue since the relocation to the city
So the theory about migrating solubles might be part of the
answer.
Kathy
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of
Dave
Finkelnburg
Sent: Tuesday, January 02, 2007 11:03 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Bisque ware turns yellow- Rinsing???????
John, Beth,
Dr. William Carty at Alfred claims firing
dehydroxylates kaolin (drives the water off it). As a
result, he says, the fired surface of the clay is
somewhat hydrophobic (repels water). Dipping the ware
in water, sponging it, etc permits the clay to attach
itself to some water (rehydroxylates the clay) and
renders the surface hydrophyllic again (attracts
water). As a result, the surface is less prone to
glaze faults.
I do not know whether his statements are accurate.
I have never read this in the published literature.
I have not tested it personally. There are other
variables, like glaze composition, surface roughness
of the ware, dust, etc. which would make a test
difficult. I have found Carty to be a credible source
of such information, given that his Ph.D. is in
surface chemistry and he has worked quite a bit with
clay products, but I'm biased because he was my MS
advisor.
Good glazing,
Dave Finkelnburg
--- John Hesselberth
wrote:
> > On Jan 2, 2007, at 11:40 AM, Beth Spindler wrote:
> > Am I missing a step or what? I have never rinsed
> >bisque ware from the kiln. Do I need to rinse???
> Hi Beth,
My gut tells me this is one of the potters' legends
> that won't hold up to serious testing.
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection
around
http://mail.yahoo.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.
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Snail Scott on thu 4 jan 07
Some clay bodies seem more prone to this than
others. Naturally, it's more visible on pale clay.
IMCO 412 is more prone to it than other premade
bodies I've used. The yellow color develops on the
tips and edges of the forms, much in the way that
scumming occurs on earthenware - apparently
as a product of soluble minerals which leach and
migrate during drying. The color differential is
most pronounced on work which is dried fast and
unevenly, which seems to confirm this notion.
The yellow hue suggests sulfur, but this is merely
a guess. In any case, it has never affected my
glazes or other finishes.
-Snail
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