Derrick Pottery - owner - Wesley Derrick on thu 18 dec 03
I fired a really nice slender vase with a Alumina oxide recipe (Velvet
glaze) :
Gerstley Borate 30.00
Nepheline Sy 10.00
Aluminia Ox 20.00
Cobalt Carb 20.00
Rutile 20.00
and would like to refire it with some gloss "grass blade" like strokes up
the sides......
I don't want a caustic bubbled-up alien grass....just a smooth gloss
version of the velvet like matt glaze that's already on it.
Would a simple clear 80/20 glaze do the trick?
Just curious what mix would be the safest because I really don't want to
mess this one up.
I know nothing of the chemistry involved here...mixing this chem with that
chem.....so please forgive the possible simple and stupid question.
Thanks in advance.
W
Bruce Girrell on fri 19 dec 03
> I fired a really nice slender vase with a Alumina oxide recipe
> and would like to refire it with some gloss "grass blade" like strokes up
> the sides......
>
> I don't want a caustic bubbled-up alien grass....just a smooth gloss
> version of the velvet like matt glaze that's already on it.
Since the base glaze is already fired, it won't cause any bubbling problems,
just make your overglaze something smooth as well. Getting it to stick and
not peel off during the refire is the big problem. Most suggestions I have
seen center on using something sticky - sugar-based or CMC - to get the
overglaze to stick to the already fired glaze.
In the future if you want to apply brushwork over a base like this, use a
frit-based glaze, not GB. The frits do not bubble during the firing and your
brushwork will stay where you put it.
Bruce "no internym today" Girrell
Ababi on fri 19 dec 03
Hello W
I give you a hard offer and an easy one.
The hard offer is to take that nice piece you have made and try five
strokes of materials and write down what you will do.
My suggestion:
One thin stroke with the 80/20 and one thick
One with 3110 and one thick
The fifth you can try the wildest guess 20 kaolin and 80 soda
bicarbonate.
You might be mad at me but you might learn a lot.
The second advice will be to make on test bars that velvet glaze. Sign
them with numbers either when you make them or with wax resist.
I used to make kind of anvil look upside down T shape long, like a
railway- I stuck to it chrome nickel wire and fired- of course raku
resist claybody. That unit survived some raku firings.
The tile with a small hole - will be connected to that railway.
Now you can glaze it. Try any glaze you imagine.
Any frit you imagine.
You can do it in one firing or multi firing
As for the glaze - it is more like the very high copper glaze with the
frit as glue.
Because the cobalt is a very strong flux - the very high alumina had to
be added in order to make it velvety - like.
Have fun
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Derrick
Pottery - owner - Wesley Derrick
Sent: Friday, December 19, 2003 6:21 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Raku Glaze Question - Glossing over an Alumina Oxide Matt Glaze
I fired a really nice slender vase with a Alumina oxide recipe (Velvet
glaze) :
Gerstley Borate 30.00
Nepheline Sy 10.00
Aluminia Ox 20.00
Cobalt Carb 20.00
Rutile 20.00
and would like to refire it with some gloss "grass blade" like strokes
up
the sides......
I don't want a caustic bubbled-up alien grass....just a smooth gloss
version of the velvet like matt glaze that's already on it.
Would a simple clear 80/20 glaze do the trick?
Just curious what mix would be the safest because I really don't want to
mess this one up.
I know nothing of the chemistry involved here...mixing this chem with
that
chem.....so please forgive the possible simple and stupid question.
Thanks in advance.
W
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Wesley Derrick - Derrick Pottery - Raymond, MS on mon 22 dec 03
Thank you all!...My intention was to get the pc. photographed however
company came over and it sold before it got a chance to dry off!!!.
a mixture of 3110 & Gerstley Borate worked great.
..the vase glazed with a high Alumina Oxide glaze (velvet glaze) was turned
upside down and the 3110/GB mixture was dripped down towards the
rim...overlapping and beading up at the end of the run closest to the rim
(top of the vase).
Refired and pulled at 1700F, the mixture was non moving, flat but raised
above the base glaze slightly (almost post-firing applied looking) and
milky white where thick, overlapping, and beaded at the end of the drip.
Some of the thick areas exhibited small gas bubbles but not many. Possibly
a good soak or firing slightly higher would pull them out.
It turned out really nice and gave me several things to experiment with.
I have 15 handbuilt crosses to glaze and fire tonight...so I better get off
the computer....
Thanks again,
wesley derrick
Derrick Pottery
Raymond, MS
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