Bruce Girrell on mon 26 oct 09
Since the Yellow Salt glaze has been a subject of discussion here recently,=
=3D
I posted a couple of photos of our results with the glaze:
Here is a vase with Yellow Salt applied over Black Teadust on a porcelain c=
=3D
lay body:
http://farm3.static.flickr.com/2637/4048135699_aca5b45380_o.jpg
This firing went to cone 12 and was heavily reduced. The kiln was bricked a=
=3D
t peak temperature, so it never got any significant oxygen during the cool =
=3D
down.* As a result, the Yellow Salt is almost white and the Black Teadust d=
=3D
id not develop the little green crystals from which it derives its name. St=
=3D
ill, the effect is very nice.
This was a totally nondescript bowl that was glazed in a manner similar to =
=3D
the vase above. It is also a porcelain clay body.
http://farm3.static.flickr.com/2687/4048880412_3da91c21e6_o.jpg
This firing was just a bit cooler, pushing cone 11. After hitting peak temp=
=3D
erature, the gas pressure was reduced from 10 psi to 5 psi without changing=
=3D
the damper, which changed the atmosphere from reduction to oxidation. The =
=3D
oxidizing atmosphere was maintained for 1/2 hour.
As a result of the reoxidation, the Yellow Salt turned its characteristic l=
=3D
ight yellow color and the Black Teadust got its green crystals (visible in =
=3D
the darkest band at the left of the bowl. What was a bowl so devoid of char=
=3D
acter that it almost didn't get fired turned into a nice little cereal bowl=
=3D
for our cupboard.
Someone asked why "salt" is contained in the name of Yellow Salt and I'm no=
=3D
t sure if anyone ever answered that. It is my understanding that this glaze=
=3D
was used in salt firings. I have not tried it in a salt kiln, nor have I s=
=3D
een results from a salt firing with this glaze.
During the discussion of Yellow Salt and its apparent low silica content, I=
=3D
believe I also talked a bit about Reitz Green, another glaze we have playe=
=3D
d with lately. Here is a platter done in Reitz Green:
http://farm3.static.flickr.com/2754/4048135565_935dae089e_o.jpg
The platter was fired to just over cone 10 with an oxidizing soak, as with =
=3D
the little bowl.
We got the Reitz Green recipe from John Britt's High Fire Glazes book, whic=
=3D
h includes a photo of a gorgeous faceted pitcher in Reitz Green.
While not from this firing, this kiln log is very representative of how the=
=3D
bowl and the platter were fired.:
http://farm3.static.flickr.com/2548/3998368030_a82d5b5643_o.jpg
Both of these glazes have produced very positive results for us with essent=
=3D
ially no tinkering. The Reitz Green is sensitive to overfiring and will dev=
=3D
elop a bazillion tiny blisters if overfired. Don't go over cone 10. Someone=
=3D
posted to the list a month or so ago asking about pinholing in Reitz Green=
=3D
. The blistering that we have observed, as opposed to pinholing, may be wha=
=3D
t the person was encountering. The blisters are very small.
Bruce Girrell
hoping all the links work
* Lack of oxygen was also indicated by the body color of the ware. Our oven=
=3D
ware clay body, which normally comes out a lovely toast brown, was a dull g=
=3D
ray. Here is one more link that shows how body (and glaze) color develop as=
=3D
a result of oxidation during the cool down phase of the firing:
http://farm3.static.flickr.com/2475/4049040046_52810e6170_o.jpg=3D
Veena Raghavan on thu 29 oct 09
Hi Bruce,
Thank you for sharing your results. I love the combination of the Yellow
Salt over the Teadust. The bowl is really great.
Thanks for sharing.
Veena
In a message dated 10/27/2009 7:57:21 AM Eastern Daylight Time,
bigirrell@MICROLINETC.COM writes:
>
> Here is a vase with Yellow Salt applied over Black Teadust on a porcelain
> clay body:
> http://farm3.static.flickr.com/2637/4048135699_aca5b45380_o.jpg
> This firing went to cone 12 and was heavily reduced. The kiln was bricked
> at peak temperature, so it never got any significant oxygen during the co=
ol
> down.* As a result, the Yellow Salt is almost white and the Black Teadust
> did not develop the little green crystals from which it derives its name.
> Still, the effect is very nice.
>
> This was a totally nondescript bowl that was glazed in a manner similar t=
o
> the vase above. It is also a porcelain clay body.
> http://farm3.static.flickr.com/2687/4048880412_3da91c21e6_o.jpg
> This firing was just a bit cooler, pushing cone 11. After hitting peak
> temperature, the gas pressure was reduced from 10 psi to 5 psi without
> changing the damper, which changed the atmosphere from reduction to oxida=
tion. The
> oxidizing atmosphere was maintained for 1/2 hour.
>
> As a result of the reoxidation, the Yellow Salt turned its characteristic
> light yellow color and the Black Teadust got its green crystals (visible =
in
> the darkest band at the left of the bowl. What was a bowl so devoid of
> character that it almost didn't get fired turned into a nice little cerea=
l
> bowl for our cupboard.
>
> Someone asked why "salt" is contained in the name of Yellow Salt and I'm
> not sure if anyone ever answered that. It is my understanding that this
> glaze was used in salt firings. I have not tried it in a salt kiln, nor h=
ave I
> seen results from a salt firing with this glaze.
>
> During the discussion of Yellow Salt and its apparent low silica content,
> I believe I also talked a bit about Reitz Green, another glaze we have
> played with lately. Here is a platter done in Reitz Green:
> http://farm3.static.flickr.com/2754/4048135565_935dae089e_o.jpg
> The platter was fired to just over cone 10 with an oxidizing soak, as wit=
h
> the little bowl.
> We got the Reitz Green recipe from John Britt's High Fire Glazes book,
> which includes a photo of a gorgeous faceted pitcher in Reitz Green.
>
> While not from this firing, this kiln log is very representative of how
> the bowl and the platter were fired.:
> http://farm3.static.flickr.com/2548/3998368030_a82d5b5643_o.jpg
>
>
> Both of these glazes have produced very positive results for us with
> essentially no tinkering. The Reitz Green is sensitive to overfiring and =
will
> develop a bazillion tiny blisters if overfired. Don't go over cone 10.
> Someone posted to the list a month or so ago asking about pinholing in Re=
itz
> Green. The blistering that we have observed, as opposed to pinholing, may=
be
> what the person was encountering. The blisters are very small.
>
> Bruce Girrell
> hoping all the links work
>
>
> * Lack of oxygen was also indicated by the body color of the ware. Our
> ovenware clay body, which normally comes out a lovely toast brown, was a =
dull
> gray. Here is one more link that shows how body (and glaze) color develop
> as a result of oxidation during the cool down phase of the firing:
> http://farm3.static.flickr.com/2475/4049040046_52810e6170_o.jpg=3D
VeenaRaghavan@cs.com
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