John Anthony on sun 9 feb 03
Hi all- A question for the glaze chemists among us. I have been mixing
some cone ^ oxidation tests, and I discovered midway through that I have
two bags of zinc oxide
(or at least two bags labeled zinc oxide by the suppliers) that i
purchased from two diffwerent sources. I will of course contact them but
it's Sunday here and...
anyway one of these bags contains a very white powdery substance. kind
of lightweight, that has small clumps in it which break apart if
squeezed. The material in the second bag is heavier, soapy as opposed to
powdery (like a spar) and adheres to itself in small compressed
platelike clumps if squeezed.
Might anyone know if these could both be zinc oxide? or hich one is more
likely to be? Thanks
John Anthony
Red Hill Pottery
David Hendley on sun 9 feb 03
Zinc oxide is known to absorb moisture. In fact, it can start out fluffy and
make rock-hard chunks over the years.
Compared to other ceramic materials like air floated clay, though, it is
never "lightweight".
If your zinc oxide has absorbed a lot of moisture you might want to
calcine it by heating it, but I'm not sure how hot it should be heated.
Anyone know the proper temperature?
David Hendley
Maydelle, Texas
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
> anyway one of these bags contains a very white powdery substance. kind
> of lightweight, that has small clumps in it which break apart if
> squeezed. The material in the second bag is heavier, soapy as opposed to
> powdery (like a spar) and adheres to itself in small compressed
> platelike clumps if squeezed.
> Might anyone know if these could both be zinc oxide? or hich one is more
> likely to be? Thanks
Marcia Selsor on sun 9 feb 03
I think my zinc is soapy feeling but older zinc does clump up. Do a 100
gram glaze test with each and see if it is the same.
About 15 years ago Cornwall stone use to be blue when it arrive. We are
dealing with mined ingredients and I am sure the veins vary from
location to location.
Best wishes,
marcia in montana where it is sunny and snow is melting.
John Anthony wrote:
> Hi all- A question for the glaze chemists among us. I have been mixing
> some cone ^ oxidation tests, and I discovered midway through that I have
> two bags of zinc oxide
> (or at least two bags labeled zinc oxide by the suppliers) that i
> purchased from two diffwerent sources. I will of course contact them but
> it's Sunday here and...
> anyway one of these bags contains a very white powdery substance. kind
> of lightweight, that has small clumps in it which break apart if
> squeezed. The material in the second bag is heavier, soapy as opposed to
> powdery (like a spar) and adheres to itself in small compressed
> platelike clumps if squeezed.
> Might anyone know if these could both be zinc oxide? or hich one is more
> likely to be? Thanks
> John Anthony
> Red Hill Pottery
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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> melpots@pclink.com.
>
--
Tuscany in 2003
http://home.attbi.com/~m.selsor/Tuscany2003.html
Snail Scott on sun 9 feb 03
At 04:04 PM 2/9/03 -0600, you wrote:
>If your zinc oxide has absorbed a lot of moisture you might want to
>calcine it by heating it, but I'm not sure how hot it should be heated.
>Anyone know the proper temperature?
I don't know how low you could calcine it and
get the effect; probably pretty low. I just
toss mine into my regular ^04 bisque firings,
though; easy, and works fine.
-Snail
Tom Buck on tue 11 feb 03
David:
Since Zinc Oxide melts at 1975 oC (3587 oF), the sintering point
will be around half that, say 1000 oC (1832 oF). So for those who do soft
bisquing (C06) or even hard bisquing (C04), putting "weathered" ZnO in
a bisque load would work fine to calcine it. Use an unglazed pot to hold
it.
best. peace. Tom B
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
On Sun, 9 Feb 2003, David Hendley wrote:
> Zinc oxide is known to absorb moisture. In fact, it can start out fluffy and
> make rock-hard chunks over the years.
> Compared to other ceramic materials like air floated clay, though, it is
> never "lightweight".
> If your zinc oxide has absorbed a lot of moisture you might want to
> calcine it by heating it, but I'm not sure how hot it should be heated.
> Anyone know the proper temperature?
> David Hendley
> Maydelle, Texas
> david@farmpots.com
> http://www.farmpots.com
>
>
>
> ----- Original Message -----
> > anyway one of these bags contains a very white powdery substance. kind
> > of lightweight, that has small clumps in it which break apart if
> > squeezed. The material in the second bag is heavier, soapy as opposed to
> > powdery (like a spar) and adheres to itself in small compressed
> > platelike clumps if squeezed.
> > Might anyone know if these could both be zinc oxide? or hich one is more
> > likely to be? Thanks
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
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