dannon rhudy on sat 6 aug 05
You ALWAYS need to test if you are in doubt
about the safety of a glaze. You'd also need to
test to see what the weathered bronze would
LOOK like, covered by layers of other glazes.
The glazes will interact when they melt; without
tests, you won't know what migrates to the top,
visually or otherwise.
Let us know what you find out.
regards
Dannon Rhudy
> I'm wondering if Pinnell's Weathered Bronze (non-food safe) was placed
> under two properly fired layers of MC6 glazes, one of which was a liner
> glaze, would it be food safe or do the chemicals interact such that the
> combination would still need to be tested?
Belinda Willis on sun 7 aug 05
So many things to learn.....
I'm wondering if Pinnell's Weathered Bronze (non-food safe) was placed
under two properly fired layers of MC6 glazes, one of which was a liner
glaze, would it be food safe or do the chemicals interact such that the
combination would still need to be tested?
Thank-you in advance.
Belinda Willis
Tony Ferguson on sun 7 aug 05
Belinda,
Yes you can but you need to test the glaze for leaching. A common technique I've seen some folks (this is where glaze fit really comes into play) do is cover a non-safe glaze with a clear glaze around the lip or where food will come into contact. I would still test it for leaching, however because if the clear crazes, it make leach through that layer.
Tony Ferguson
Belinda Willis wrote:
So many things to learn.....
I'm wondering if Pinnell's Weathered Bronze (non-food safe) was placed
under two properly fired layers of MC6 glazes, one of which was a liner
glaze, would it be food safe or do the chemicals interact such that the
combination would still need to be tested?
Thank-you in advance.
Belinda Willis
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Belinda Willis on sun 7 aug 05
I ask about the food safety of such layering because I played around with
putting Weathered Bronze over and under two MC6 glazes and portions of the
results look GREAT. I did it inside a junk bowl to see what it'd look like
and how it might move.
I dipped 1/3 of the bowl in a version of Sky Blue - it was the Sky Blue
oxides in the Glossy Clear Liner glaze - then I painted a layer of
Weathered Bronze over a portion of that and onto the unglazed area beside
the Sky Blue. Over the Weathered Bronze, I poured a layer of liner glaze
with 5% zircopax. The white liner glaze also covered a portion of the Sky
Blue/Weathered Bronze so in that area there were three layers.
Where the Weathered Bronze covered the Sky Blue, there are dry patches of
matt green on top of a glossy deep blue field... a nice color interaction
but not a pleasing surface combination.
Where the Weathered Bronze is under the white liner glaze, it became a
varied field of green that has small islands of matt crystals on top of
gloss. Where the Weathered Bronze is thin, it=92s a wonderful chartreuse
green and where the WB is thicker, it=92s a pleasing olive green. Again,
because of the very small patches of dry matt on top of gloss, the surface
has a slightly unappealing quality tho over a larger area, it might be
interesting.
But, oh, in that area where the three glazes are layered, what potential!
It formed riverlets down the inside of the bowl of deep blue gloss,
interlaced with olive green, interlaced with chartreuse and where the
fingers of color touch, they blend into gorgeous shades of blue/green.
Beside the field of Sky Blue, it=92s gorgeous. The green fingers tend to be
matt but they aren=92t overly dry and even with the matt/glossy interplay,
its pretty.
So, next I=92ll try putting the Weathered Bronze under both of the MC6 layer=
s
rather than sandwiched between them in hopes of loosing the remaining matt
surface but retaining the riverlets of interlaced colors. And I=92ll devote
the entire inside surface of a bowl to the layered combinations rather than
just a narrow strip. If it works, then I=92ll test it. Unfortunately, I
don=92t get to fire the kiln very often so I won=92t be able to report back
very soon.
If this combination interacts the same way regularly, it would be fantastic
on a wall platter.
Belinda
Ron Roy on sun 7 aug 05
I think it would be better to avoid the "food safe" label - but if you put
a durable glaze over an unstable glaze the result will be more stability -
- there is no doubt about that - the result will be quite different looking
in this case however.
I expect John will answer this as well - he has done the experiments and
had the results tested.
RR
>So many things to learn.....
>
>I'm wondering if Pinnell's Weathered Bronze (non-food safe) was placed
>under two properly fired layers of MC6 glazes, one of which was a liner
>glaze, would it be food safe or do the chemicals interact such that the
>combination would still need to be tested?
>
>Thank-you in advance.
>
>Belinda Willis
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
John Hesselberth on sun 7 aug 05
Hi Belinda,
Actually Pete's Weathered Bronze is a pretty durable glaze in my
testing. Perhaps surprisingly so--but it is if fired to a full cone 6.
But to try to answer your question, yes layering a stable glaze over a
less stable glaze will help. In the limited testing I have done it cut
the leaching by a factor of 10 or so. Is that enough? Well, it depends
on how unstable the underlying glaze is and how thick the layer of
stable glaze is. It might also depend on how long you let the glaze
soak at peak temperature. Only testing can tell for sure.
Regards,
John
On Aug 7, 2005, at 12:11 AM, Belinda Willis wrote:
> So many things to learn.....
>
> I'm wondering if Pinnell's Weathered Bronze (non-food safe) was placed
> under two properly fired layers of MC6 glazes, one of which was a liner
> glaze, would it be food safe or do the chemicals interact such that the
> combination would still need to be tested?
>
> Thank-you in advance.
>
> Belinda Willis
>
> _______________________________________________________________________
> _______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
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