terryh on tue 27 jan 04
Ababi wrote,
>Sat, 24 Jan 2004 08:03:08 +0200
>Hi Barbara
>You change the 100 barium into 75 strontium carbonate
>This glaze will be better but not foodsafe because of the low firing and
>the high copper.
made me wonder how foodsafe the copper red in cone 10 firing is. any idea?
yes, i know, one can check for leach. but never seen any report of test
results, either positive or negative, even if anecdotal.
terry hagiwara
terryh@pdq.net
http://www.geocities.com/terry.hagiwara
Ababi Sharon on tue 27 jan 04
You must test it
By the way (OT) years ago when I run our educational zoo I had to
prepare myself the grain mix for the sheep. The available that we had
for calves had an add of 10 PPM copper while sheep can have no more
than 4 PPM.
I know copper can kill sheep I know this is a "food for thought"!
Ababi Sharon
Glaze addict
Kibbutz Shoval=A0 Israel
ababisha@shoval.org.il
http://ababi.active.co.il
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
Ceramics forum in Hebrew
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of terryh
Sent: Tuesday, January 27, 2004 4:28 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Convert Glaze to No Barium; is Copper Red safe?
Ababi wrote,
>Sat, 24 Jan 2004 08:03:08 +0200
>Hi Barbara
>You change the 100 barium into 75 strontium carbonate
>This glaze will be better but not foodsafe because of the low firing
and
>the high copper.
made me wonder how foodsafe the copper red in cone 10 firing is. any
idea?
yes, i know, one can check for leach. but never seen any report of test
results, either positive or negative, even if anecdotal.
terry hagiwara
terryh@pdq.net
http://www.geocities.com/terry.hagiwara
________________________________________________________________________
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terryh on wed 28 jan 04
Ababi wrote:
>Tue, 27 Jan 2004 20:15:56 +0200
>You must test it
>By the way (OT) years ago when I run our educational zoo I had to
>prepare myself the grain mix for the sheep. The available that we had
>for calves had an add of 10 PPM copper while sheep can have no more
>than 4 PPM.
>I know copper can kill sheep I know this is a "food for thought"!
you mean you had tested and found some leached copper and some didn't.
so you suggest one has to test it?
or, is this a general good advise?
if copper leaches out from cone 10 fired pots and sometimes not,
what is the odd? what are the conditions behind? underfired?
btw, i read your zoo story differently. feed company added up to 10
and 4 ppm Cu (in some form), didn't it? for calves and sheep need
copper in their diet. (but, too much is always bad :) otherwise, why
did they ADD copper, if not for some germicide or preserve or ...?
or, are you talking about copper contamination?
are you sure if (more than 4 ppm) Cu might kill sheep?
i am getting curious about food-safety of copper red dinner ware.
haven't seen many. many i have seen had copper red outside but
white glaze inside (bawl). one reason, i used to think, is that
it is very difficult to present food on oxen blood red plate and bawl.
on the other hand, red lacquer ware are very common. (but that
red is not crimson red, more to orange/brown red.) is copper
leaching the reason why there aren't many copper red dinner ware?
sliced cucumber looks appetizing on a small copper red bowl tonight :)
terry
terry hagiwara
terryh@pdq.net
http://www.geocities.com/terry.hagiwara
Ababi Sharon on thu 29 jan 04
I said you should test I did not say one test was good the other was
bad- perhaps the "Outlook" had changed my words.
I run an educational zoo.
We had about 1000 cows they made food for them they did not make food
for my four sheep. ( They did not ship the food for four sheep)
There was another story, years ago they gave unwisely I think a bad
advise or a mistake of the vitamin company this calf food copper rich,
to our sheep (when we had them as a branch of our farm). They stopped it
when some sheep passed away.
Ababi
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of terryh
Sent: Thursday, January 29, 2004 3:23 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Convert Glaze to No Barium; is Copper Red safe?
Ababi wrote:
>Tue, 27 Jan 2004 20:15:56 +0200
>You must test it
>By the way (OT) years ago when I run our educational zoo I had to
>prepare myself the grain mix for the sheep. The available that we had
>for calves had an add of 10 PPM copper while sheep can have no more
>than 4 PPM.
>I know copper can kill sheep I know this is a "food for thought"!
you mean you had tested and found some leached copper and some didn't.
so you suggest one has to test it?
or, is this a general good advise?
if copper leaches out from cone 10 fired pots and sometimes not,
what is the odd? what are the conditions behind? underfired?
btw, i read your zoo story differently. feed company added up to 10
and 4 ppm Cu (in some form), didn't it? for calves and sheep need
copper in their diet. (but, too much is always bad :) otherwise, why
did they ADD copper, if not for some germicide or preserve or ...?
or, are you talking about copper contamination?
are you sure if (more than 4 ppm) Cu might kill sheep?
i am getting curious about food-safety of copper red dinner ware.
haven't seen many. many i have seen had copper red outside but
white glaze inside (bawl). one reason, i used to think, is that
it is very difficult to present food on oxen blood red plate and bawl.
on the other hand, red lacquer ware are very common. (but that
red is not crimson red, more to orange/brown red.) is copper
leaching the reason why there aren't many copper red dinner ware?
sliced cucumber looks appetizing on a small copper red bowl tonight :)
terry
terry hagiwara
terryh@pdq.net
http://www.geocities.com/terry.hagiwara
________________________________________________________________________
______
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.
Ivor and Olive Lewis on fri 30 jan 04
Dear terryh,
You ask <not, what is the odd? what are the conditions behind? underfired?>>
I don't if anyone is sure about the chemistry of copper, either as =
dissolved ions or as colloidal oxide in a silicate melt.=20
We are ignorant of the Chemistry of silica-copper systems. The =
Geologists might throw some light on the topic by explaining why we do =
not get Pure Copper Silicate ores.
Best regards,
Ivor Lewis. Redhill, South Australia
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