Gary Beckwith on mon 9 aug 10
Hi all
I've been rakuing with a white crackle glaze over soldate 60. It's a stand=
ard
formula:
80 Gerstley Borate
20 Nepheline Syenite
10 Zircopax.
I've gotten some really nice results with it, and add copper carb to it
sometimes.
I had the notion that I could coat the inside of the pieces with a low fire
clear glaze; this way they would be water tight.
Usually after 1500F, my pieces start to blister and then at around 1800+, t=
hey
smooth out and become nice and glistening, ready to take out. But with the
addition of the interior glaze, the blisters wouldn't go away, even when I =
got
up to 1900F, they were still there. So here are some questions?
1. Is this not a good thing to do with Raku? Does anyone else glaze the
insides?
2. If I were to "soak" at a particular temp for a longer period of time, w=
ould
that help?
3. Or if I were to go higher with the temp, would that help?
I'm primarily doing vases (largest ones 12-15" high) and wanted to make the=
m
water tight. (I know there are ways to water-tight the piece post-firing, =
but I
thought this would save a step in the process). Also, I take about 45 min=
s to
bring the kiln up to to temperature, slowing increasing the gas and opening=
the
pressure from about 2psi to 8psi at final temp. It's a Ward MR750 burner. =
The
kiln is a old oil drum lined with kaowool.
Any suggestions would be greatly appreciated.
Thank you,
Gary Beckwith
Auburn, CA
paul gerhold on wed 11 aug 10
Gary,
Are you glazing the inside first or the outside and how thin are the
pieces. Why are you trying to make Raku waterproof . My experience says
blisters are blister and will not disappear with longer or higher firing at
least within reasonable limits. Also how are you glazing. Are you filling
inside and then pouring glaze out, brushing or what? The way you are
applying the glaze is probably what is loosing the outside glaze and thus
causing blisters.
As an aside you will probably not be sucessful in making Raku really water
tight by glazing. If you don't see the inside you can fire the way you use=
d
to fire and then use fiberglass resin to waterproof the pot. Did this with
a piece about 30 years ago and it still holds water and flowers.
Paul
David Woof on wed 18 aug 10
Gary=3D2C A mature glaze=3D2C even at stoneware temperature=3D2C doesn'=
t insu=3D
re water proof if the underlying clay body is not vitrified to at least a 2=
=3D
.5% absorption. So first step=3D3B give up the waterproof glaze idea. 2n=
d =3D
step=3D3B don't make anything that someone would ever in the history of ame=
ri=3D
can raku try to store food in or eat and drink from if you treat the inside=
=3D
with a chemical waterproofing compound. 3rd=3D3B if you need to glaze t=
he=3D
inside for aesthetic concerns=3D2C concoct one that matures at a bit lower=
t=3D
emp and produces less off gassing and apply a thinner coat and work up if t=
=3D
here are indications of potential success. Learn your materials and let t=
=3D
his all continue to challenge your thinking. Try stuff=3D2C keep records.=
=3D
let us know what you find.
=3D20
Your questions say you are thinking and pondering. I like that.=3D20
=3D20
So if you are inclined to go and gather your own pine pitch and while the v=
=3D
essel is hot enough to melt it and absorb you will have a measure of sealan=
=3D
t quality. The pot will have a nice lingering odor of piney earthiness and=
=3D
fire. =3D20
=3D20
Tell the white folks your Indian Grandmother taught you=3D3B the wanna b's=
w=3D
ill lap it up. Funny though how=3D2C sometimes still=3D2C things change t=
o qu=3D
iet if you say you have an Indian Grandfather. How deep it secretly runs i=
=3D
n the deepest recesses of good people's hearts. Let's all get out our flas=
=3D
hlights and explore our hidden places.
=3D20
Misneach=3D2C =3D20
=3D20
David Thingmaker.....over 21 in Clarkdale Arizona=3D2C undocumented and ill=
eg=3D
al somewhere I'm sure!!! oops there goes sheriff joe bigpile tiptoeing th=
=3D
ru my tulips again=3D2C hunting thru Patio Town=3D3B squinting through his =
prof=3D
ile catalogue. Best to stay in out of the sun. Suntans are getting extree=
=3D
mly unpopular.
_______________________________________________________
=3D20
13. Raku Firing - glazing the inside
Posted by: "Gary Beckwith" garyb444@SBCGLOBAL.NET=3D20
Date: Mon Aug 9=3D2C 2010 11:45 am ((PDT))
Hi all
I've been rakuing with a white crackle glaze over soldate 60. It's a standa=
=3D
rd
formula:
80 Gerstley Borate
20 Nepheline Syenite
10 Zircopax.
I've gotten some really nice results with it=3D2C and add copper carb to it
sometimes.
I had the notion that I could coat the inside of the pieces with a low fire
clear glaze=3D3B this way they would be water tight.
Usually after 1500F=3D2C my pieces start to blister and then at around 1800=
+=3D
=3D2C they
smooth out and become nice and glistening=3D2C ready to take out. But with =
th=3D
e
addition of the interior glaze=3D2C the blisters wouldn't go away=3D2C even=
whe=3D
n I got
up to 1900F=3D2C they were still there. So here are some questions?
1. Is this not a good thing to do with Raku? Does anyone else glaze the
insides?
2. If I were to "soak" at a particular temp for a longer period of time=3D2=
C =3D
would
that help?
3. Or if I were to go higher with the temp=3D2C would that help?
I'm primarily doing vases (largest ones 12-15" high) and wanted to make the=
=3D
m
water tight. (I know there are ways to water-tight the piece post-firing=3D=
2C=3D
but I
thought this would save a step in the process). Also=3D2C I take about 45 m=
in=3D
s to
bring the kiln up to to temperature=3D2C slowing increasing the gas and ope=
ni=3D
ng the
pressure from about 2psi to 8psi at final temp. It's a Ward MR750 burner. T=
=3D
he
kiln is a old oil drum lined with kaowool.
Any suggestions would be greatly appreciated.
Thank you=3D2C
Gary Beckwith
Auburn=3D2C CA
=3D20
=3D20
=3D
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