Pottery by Dai on mon 10 jul 00
Ken, the website address (Http://www.mdc.net/~rjwilt/info/DEGRaku)
resulted in a "Not Found" response---are you sure you had it right?
Dai - in Kelowna, B.C.
potterybydai@home.com
There is an alarming increase in the number of things that I know nothing
about.
Karen Shapiro on mon 10 jul 00
Hi clayarters,
Could someone PLEASE help me out with a "non-gerstley
borate" transparent raku glaze. I have been having
trouble with my good old standard (70/30 and 80/20)
glazes. I'd love to have one based on a frit, like
3134. I am swamped with work at this point and don't
have the time to do a lot of testing.
thanks so much,
Karen in Gualala
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Ken Kang on mon 10 jul 00
=
>
Could someone PLEASE help me out with a "non-gerstley
borate" transparent raku glaze. I have been having
trouble with my good old standard (70/30 and 80/20)
glazes. I'd love to have one based on a frit, like
3134. I am swamped with work at this point and don't
have the time to do a lot of testing.
thanks so much,
Karen in Gualala<
Karen,
Go to web page:Http://www.mdc.net/~rjwilt/info/DEGRaku.htm
Lots of recipies, I'm sure you'll find something there.
Aloha, Ken
Bruce Girrell on mon 10 jul 00
Karen,
Recently, I posted the following white GB-free glaze, along with preliminary
results in using it. It showed up on my mail, but it generated ZERO response
and I don't see it in the archives, so I'll copy it below. To make a
transparent, simply remove the tin oxide. Also see
http://www.escribe.com/art/clay/m38006.html for some other recipes.
Oh, an update - The Tak glaze gives a nice white, but is _very_ unfriendly
to other glazes. It dries to a powdery surface and any overcoat of another
glaze simply flakes off. I have had better luck when I rewetted the glaze
surface prior to the overcoat, but I have not yet tried adding CMC or
anything else to avoid the powder-like surface (suggestions anyone?). Of the
two glazes that I reported on, the Branfman glaze had a better white in its
original formulation, but I added some more tin and zircopax to the Tak and
it gives a brighter white now.
The original post:
This past weekend was glaze mixing day at the Girrell household. We've been
using a white crackle glaze that was OK, but just didn't make our hearts go
pitter-pat.
I looked back through my pile of printouts of glaze recipes. Lo and behold
there was one that didn't call for gerstley borate. I mixed up a couple kg
of it and another glaze that did use GB and fired them together on a scrap
bowl and some test tiles.
The recipes:
Ferro Frit 3134 100
Silica 6
EPK 10
Tin oxide 10
Pinch of bentonite (I used about 2 Tablespoons in a 3 kg batch)
Gerstley borate 65
Tennessee ball clay 5
Nepheline syenite 15
Flint 5
Tin oxide 10
Other possibly important stuff:
The clay body for the test pieces was Great Lakes Clay raku body (I forget
the exact name, but it's the one with only fine grog). All test tiles and
the bowl were fired together and all placed in the same reduction bin.
The results:
Both recipes produced a nice crackle on the bowl, but the GB free recipe had
a larger mesh size, i.e., the cracks were further apart. The glaze that we
had been using produced a crackle that had too fine of a crackle, so this
was a good thing. The GB recipe gave a brighter white and I attribute that
to the thickness of the glaze coat. Frit based glazes just don't seem to
adhere as thickly.
The results on the test tiles were not as telling. The tiles had a lot of
texture, which in my experience tends to reduce crackle, and they had been
washed prior to glaze application, so the glaze was not going on thickly.
The ones that did show crackle were mostly the GB free recipe with several
dips.
Melting of the GB-free glaze was nice and uniform without any bubbling.
Despite the high frit content, the bucket properties are pretty good.
Apparently, the EPK and bentonite provide enough suspension for the frit so
that it doesn't sink and harden. The GB recipe showed the usual bubbling
during the firing. The GB-based glaze goes on the pot nicer with a nice
thick uniform coat. The frit glaze goes on uniformly, but tends to be
thinner.
All in all, the GB free recipe seems to be a winner. I added a little more
opacifier to boost the whiteness and if we take the time to get it on
thicker, I'm sure it will do well. More tests tonight.
Credit where credit is due dept:
The recipes were from a large collection put together by Dewitt Gimblet. See
http://www.mdc.net/~rjwilt/info/DEGRaku.htm for the whole list. The GB based
recipe is called Basic White Crackle and is attributed to Steve Branfman.
The GB-free recipe is named Tak and was collected from mel jacobson, who
credited it with this note: "is a kurt wild glaze....it came from a student
named takahara. it is nice...we have all used it."
Bruce & Lynne Girrell
in Northern Michigan, just back from a good weekend selling at a local music
festival (Blissfest)
Music festivals are just a heck of a lot nicer way to pass the time than
craft fairs.
Alisa and Claus Clausen on tue 11 jul 00
Dear Karen,
I use an 80/20 combination of Cornwall stone/Neph. Sye. =20
What I call a transparent is actually a whitish crackle, that
can be opacified much more with zircon, etc.
Best regards,
Alisa in Denmark
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Steve Mills on tue 11 jul 00
This is the one I use:
ANY Fritt.............85 parts by weight
China Clay (Kaolin)...15.
Add 1 percent Bentonite to stop it setting like concrete in the bucket
I prefer High Alkaline Fritts for colour response.
Steve
Bath
UK
In message , Karen Shapiro writes
>Hi clayarters,
>
>Could someone PLEASE help me out with a "non-gerstley
>borate" transparent raku glaze. I have been having
>trouble with my good old standard (70/30 and 80/20)
>glazes. I'd love to have one based on a frit, like
>3134. I am swamped with work at this point and don't
>have the time to do a lot of testing.
>
>thanks so much,
>Karen in Gualala
>
>__________________________________________________
>Do You Yahoo!?
>Get Yahoo! Mail =96 Free email you can access from anywhere!
>http://mail.yahoo.com/
>
--
Steve Mills
Bath
UK
Ken Kang on wed 12 jul 00
Dai,
Did you forget the (.htm) at the end of the address?
Aloha, Ken
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