Ben Morrison on mon 14 may 12
However often US potters use up to 10 times the amount of Boron in glazes a=
=3D
s UK potters do Zinc.=3D0A=3D0A=3D0A=3D0A________________________________=
=3D0A From: =3D
Url Krueger =3D0ATo: Clayart@LSV.CERAMICS.ORG =3D0ASe=
nt: =3D
Monday, May 14, 2012 9:53 AM=3D0ASubject: zinc vs boron=3D0A =3D0AWhy do US=
potte=3D
rs use boron as a melter?=3D0A=3D0AHistorically I think it probably came do=
wn=3D
=3D0Ato simple economics.=3DA0 Gerstley borate=3D0Apretty much was used as =
it cam=3D
e out of=3D0Athe ground while producing zinc oxide=3D0Arequires extensive p=
roce=3D
ssing of the ore=3D0Aincluding energy intensive steps like=3D0Asintering an=
d di=3D
stillation.=3D0A=3D0ALooking at my local suppliers catalog shows=3D0Athat z=
inc ox=3D
ide, in a 50 lb bag, costs over=3D0Afour times as much as gerstley borate=
=3D0Ad=3D
oes today.=3D0A=3D0Aearl in Oregon
Url Krueger on mon 14 may 12
Why do US potters use boron as a melter?
Historically I think it probably came down
to simple economics. Gerstley borate
pretty much was used as it came out of
the ground while producing zinc oxide
requires extensive processing of the ore
including energy intensive steps like
sintering and distillation.
Looking at my local suppliers catalog shows
that zinc oxide, in a 50 lb bag, costs over
four times as much as gerstley borate
does today.
earl in Oregon
Brad Sondahl on tue 15 may 12
In my experience (and I use both extensively), boron is useful in reducing
crazing and improving glaze quality for bakeware, as well as a good melting
agent in the glaze. I used to use Frit P25, but when my supplier didn't
stock it and I got tired of paying the freight, I went to a higher boron
frit 3134. Zinc can also help with crazing, but not as much, but is a
dependable melt agent, and indispensable when it comes to crystalline
glazes (which also benefit from boron)..
Brad Sondahl sondahl.com
douglas fur on tue 15 may 12
Clayarters
Daniel Rhodes in "clay and glazes..." disses Bristol glazes as out-moded
and gives a lot of boron glazes.
So his influence lingers on???
Parmalee in his book gives zinc lots of coverage. His book is more
industry not craft oriented.
So the die was cast/
DRB
Seola Creek
douglas fur on wed 16 may 12
Brian
What gets me about boron is the slimey surface feel it gives a glaze. It
seems to be moving away from the melted stone character of "high fire"
glazes and towards saran wrap.
My hope is that ZnO will be useful in moving to ^6 without losing that
lithic texture. Does this resonate with your experience?
Duff
Seola Creek
douglas fur on thu 17 may 12
Brad
(the boron vis zinc portion came from a comment from a UK clayarter who
thought the percentage of mid range firing potters using zinc was higher in
the UK than in the US. My speculation to Earl on another thread was this
was due to the influence of Rhodes' *clay and glazes for the potter* who is
enthusiastic about colemanite as the studio potter's friend.)
My paradigm is a variation I did subbing mixed wood ash for part of the
SiO2 and CaO in 4,3,2,1 fired to ^6 (that was years back and I've lost that
ash source and discarded the recipe...)
To me there is a different feel to this glaze surface as compared to boron
or PbO fluxed glazes. Maybe that's all in my head, psycho-somatic or
psychotic, but think I can feel a difference.
I think James' comment on over firing is a good lead- so many gerstley
borate glazes, such as 50 % P.V.Clay +50% G.B. are over fired in so many
applications.
As for other fluxes I've recently been testing talc. It's "Buttery"
texture seems to offset the boron effect.
DRB
Seola Creek
Ben Morrison on thu 17 may 12
Hey I like saran wrap! Check the Zinc glazes in Mastering Cone 6 Glazes, th=
=3D
ere's a good recipe in there. At least it would give you a good place to st=
=3D
art if you're interested in going down that road. Here's a bit more informa=
=3D
tion I found recently expanding a bit on the Zinc Semi-matte recipe from th=
=3D
e book.=3D0A=3D0Ahttp://www.johnpost.us/Pottery%20Links/grid-glazes/grid-02=
4.ht=3D
ml =3D0A=3D0AThe recipes for that grid on in a link to the right side of th=
e pa=3D
ge.=3D0A=3D0ABest of luck=3D0A=3D0ABen=3D0A=3D0A=3D0A=3D0A_________________=
_______________=3D
=3D0A From: douglas fur <23drb50@GMAIL.COM>=3D0ATo: Clayart@LSV.CERAMICS.OR=
G =3D
=3D0ASent: Wednesday, May 16, 2012 5:58 PM=3D0ASubject: Re: Re zinc vs boro=
n=3D0A=3D
=3D0ABrian=3D0A=3D0AWhat gets me about boron is the slimey surface feel it=
gives=3D
a glaze.=3DA0 It=3D0Aseems to be moving away from the melted stone charact=
er o=3D
f "high fire"=3D0Aglazes and towards saran wrap.=3D0AMy hope is that ZnO wi=
ll b=3D
e useful in moving to ^6 without losing that=3D0Alithic texture.=3DA0 Does =
this=3D
resonate with your experience?=3D0A=3D0ADuff=3D0ASeola Creek
James Freeman on thu 17 may 12
The main cone 6 glaze that I am using on my current body of work is neph sy
based, and fluxed with roughly 10% gillespie borate (along with some other
stuff). It is not "saran wrap"-like at all, but rather a really nice,
satin matte. It only goes saran-wrap-like if over-fired. For one of my
color variations I subbed zinc for the borate, and got an almost identical
surface. I believe I used .8 zinc to 1 GB (did a line blend to find the
surface I was after), but I can't recall precisely. My notes are out in
the studio, and I am currently on the other side of my property re-siding
my garden shed (the very definition of boring and tedious, though it did
justify my purchase of a slick hardi-board shear!). I'll try to get out to
the studioe this afternoon to verify.
For whatever it's worth.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Wed, May 16, 2012 at 8:58 PM, douglas fur <23drb50@gmail.com> wrote:
> Brian
>
> What gets me about boron is the slimey surface feel it gives a glaze. It
> seems to be moving away from the melted stone character of "high fire"
> glazes and towards saran wrap.
> My hope is that ZnO will be useful in moving to ^6 without losing that
> lithic texture. Does this resonate with your experience?
>
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