nori on fri 22 aug 08
hi.
here's another glaze question.
i had some lilac mason body stain on hand & thought i'd try it in a
glaze. i used it in a cone 6 matte white from val cushing that i like a
lot.
i fire oxidation, usually at cone 7.
it came our very nice - a pale lavendar with just the faintest blue
speckle from the cobalt in the stain.
except for a skip... a place with bare clay.
so, i touched it up & refired.
wow.... the lilac faded right out to a pale blue & the specks were
greatly multiplied.
so... can anyone give me an idea why this might happen?
i'm just trying to understand the effect of refiring on the stain. hmmm.
as i recall, the stain has cobalt, manganese, zirconium, calcium...
any insights would be welcome. thanks!
sabra
--
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Ron Roy on wed 27 aug 08
Hi Sabra,
Refiring is like firing a cone higher - you get more melting because it's
easier to melt something that has already been melted. That should mean the
glaze you added should look a bit different.
If you like the effect you could fire hotter or lower the melt of the glaze.
RR
>hi.
>
>here's another glaze question.
>
>i had some lilac mason body stain on hand & thought i'd try it in a
>glaze. i used it in a cone 6 matte white from val cushing that i like a
>lot.
>
>i fire oxidation, usually at cone 7.
>
>it came our very nice - a pale lavendar with just the faintest blue
>speckle from the cobalt in the stain.
>
> except for a skip... a place with bare clay.
>
>so, i touched it up & refired.
>
>wow.... the lilac faded right out to a pale blue & the specks were
>greatly multiplied.
>
>so... can anyone give me an idea why this might happen?
>
>i'm just trying to understand the effect of refiring on the stain. hmmm.
>
>as i recall, the stain has cobalt, manganese, zirconium, calcium...
>
>any insights would be welcome. thanks!
>
>sabra
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
John Post on wed 27 aug 08
I'm betting the extra firing time allowed the calcium to grow more
matte crystals in the glaze. As these crystals grew they changed the
color of the stain and the opacity, surface texture of the glaze.
Your piece spent twice as much time in the crystal growing phase from
1800-1300 degrees F on the way down in each firing. If this glaze was
a cone 6 glossy when you fired it, it may have stood a better chance
of not changing color on the refire.
John Post
Sterling Heights, Michigan
:: cone 6 glaze website :: http://www.johnpost.us
:: elementary art website :: http://www.wemakeart.org
On Aug 27, 2008, at 2:37 PM, Ron Roy wrote:
> Hi Sabra,
>
> Refiring is like firing a cone higher - you get more melting because
> it's
> easier to melt something that has already been melted. That should
> mean the
> glaze you added should look a bit different.
>
> If you like the effect you could fire hotter or lower the melt of
> the glaze.
>
> RR
>
>> hi.
>>
>> here's another glaze question.
>>
>> i had some lilac mason body stain on hand & thought i'd try it in a
>> glaze. i used it in a cone 6 matte white from val cushing that i
>> like a
>> lot.
>>
>> i fire oxidation, usually at cone 7.
>>
>> it came our very nice - a pale lavendar with just the faintest blue
>> speckle from the cobalt in the stain.
>>
>> except for a skip... a place with bare clay.
>>
>> so, i touched it up & refired.
>>
>> wow.... the lilac faded right out to a pale blue & the specks were
>> greatly multiplied.
>>
>> so... can anyone give me an idea why this might happen?
>>
>> i'm just trying to understand the effect of refiring on the stain.
>> hmmm.
>>
>> as i recall, the stain has cobalt, manganese, zirconium, calcium...
>>
>> any insights would be welcome. thanks!
>>
>> sabra
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
Lee Love on wed 27 aug 08
On Wed, Aug 27, 2008 at 1:37 PM, Ron Roy wrote:
> Hi Sabra,
>
> Refiring is like firing a cone higher - you get more melting because it's
> easier to melt something that has already been melted. That should mean the
> glaze you added should look a bit different.
>
> If you like the effect you could fire hotter or lower the melt of the glaze.
Cones measure heat work over time and not temperature.
For example, the old woodfire kilns would rarely get much hotter
than 2000*F, but they were fired for a week or more. Longer times at
lower temperature, not to mention the cycling atmospheric environments
create much different glaze surfaces than do highly controlled, hi
temp gas firings.
The climbing kilns were more heat efficent, fired in less time and
fired glazed work that had a totally different character compared to
the older kilns.
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi
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