Ela Trent on sat 17 mar 01
Hello
Can anyone tell me if you can eat and drink out of anything with copper
carbonate which has been painted on top of the glaze before firing? Will it
poison the eater/drinker? (ie: mugs, bowls)
For that matter - if copper carbonate is in the glaze, does this also make
the pot poisonous to eat and drink out of.
The base glaze is a stoneware manly potash/china clay mix - no lead in
sight.
I know this is probably an easy one, but if anyone can enlighten me that
would be great.
Please reply to me at trentela@hotmail.com
Ta
Ela
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Craig Martell on sat 17 mar 01
Ela asked:
>Can anyone tell me if you can eat and drink out of anything with copper
>carbonate which has been painted on top of the glaze before firing? Will it
>poison the eater/drinker? (ie: mugs, bowls)
Hi Ela:
There are toxicity issues with copper. The problem with overglaze washes
containing Cu is that it's impossible to determine the concentration of the
oxide on the surface of the glaze. You also need to have an idea of how
durable the glaze is. So, you need to know the molecular formula to even
venture a guess, and that's all it would be. The only way to make any sort
of determination here would be lab tests and then it would only be valid
for the piece tested. The next time you do a series of work you could load
the brush heavier and place more copper on the surface of the glaze.
It might be best if you brush the copper washes on areas where there isn't
a food contact issue. Also, the general rule is that if you go over 4%
copper in a glaze you run the risk of leaching more copper than is
recommended. Copper increases the solubility of glazes and it's my opinion
that one needs at least 3.0 moles of silica to 1.0 moles of flux and I
would include copper in the 1.0 value here. Even if this is determined,
you would still need to test.
regards, Craig Martell in Oregon
Dan Bowen on thu 17 oct 02
The copper carbonate I recently recieved was a darker green
than previous. From the archives I understand the paler version
(powder like) which I have the most experience is hydrated and is more
unpredictable with less copper. The darker green is more dence(granular)
and goes to the bottom of my glaze bucket. I have experimented with CMC,
bentonite and flocs. I do not have a ball mill. How do keep it in
suspention or do I need to find a suplier with the lighter green color.
Thanks
Dan Bowen
Eastville Virginia
East of the Chesapeake Bay
Jonathan Kirkendall on thu 17 oct 02
Dan,
I have copper carbonate from the same batch that you do - almost like very,
very fine sand. I was completely dubious, but I have to say that I haven't
seen an impact on my glazes. Even though after much stirring and after the
application I find what I would consider to be suspiciously large amounts of
the copper carb hanging out and gossiping in the bottom of the bucket, my
glazes are still the same green as the last batch.
Jonathan in DC
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Dan Bowen
Sent: Thursday, October 17, 2002 8:19 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: copper carbonate
The copper carbonate I recently recieved was a darker green
than previous. From the archives I understand the paler version
(powder like) which I have the most experience is hydrated and is more
unpredictable with less copper. The darker green is more dence(granular)
and goes to the bottom of my glaze bucket. I have experimented with CMC,
bentonite and flocs. I do not have a ball mill. How do keep it in
suspention or do I need to find a suplier with the lighter green color.
Thanks
Dan Bowen
Eastville Virginia
East of the Chesapeake Bay
____________________________________________________________________________
__
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Dwiggins, Sandra (NIH/NCI) on thu 17 oct 02
Dan/Jonathan/Claybuds...
I just got off the phone with the person who manages our studio and we were
talking about this very thing. If bentonite, CMC, etc. doesn't work...then
what? We have a very nice stable green glaze for the students, but it is
difficult to keep that pesky green sand in suspension....
Jonathan...how do you keep the copper carbonate in suspension?
Suggestions????
Sandy
-----Original Message-----
From: Jonathan Kirkendall [mailto:Jonathan@MIRIAMSKITCHEN.ORG]
Sent: Thursday, October 17, 2002 12:20 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: copper carbonate
Dan,
I have copper carbonate from the same batch that you do - almost like very,
very fine sand. I was completely dubious, but I have to say that I haven't
seen an impact on my glazes. Even though after much stirring and after the
application I find what I would consider to be suspiciously large amounts of
the copper carb hanging out and gossiping in the bottom of the bucket, my
glazes are still the same green as the last batch.
Jonathan in DC
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Dan Bowen
Sent: Thursday, October 17, 2002 8:19 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: copper carbonate
The copper carbonate I recently recieved was a darker green
than previous. From the archives I understand the paler version
(powder like) which I have the most experience is hydrated and is more
unpredictable with less copper. The darker green is more dence(granular)
and goes to the bottom of my glaze bucket. I have experimented with CMC,
bentonite and flocs. I do not have a ball mill. How do keep it in
suspention or do I need to find a suplier with the lighter green color.
Thanks
Dan Bowen
Eastville Virginia
East of the Chesapeake Bay
____________________________________________________________________________
__
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.
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
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Lily Krakowski on thu 17 oct 02
Well, I repeat my earlier suggestion, to sieve, and grind the residue in a
mortar.
However. some glazes dislike being cold. And those really want to sit by
the stove at night and be warm, as in Summer. If your glaze is just
developing this settling out, maybe the poor baby is too cold.
Dwiggins, Sandra (NIH/NCI) writes:
> Dan/Jonathan/Claybuds...
> I just got off the phone with the person who manages our studio and we were
> talking about this very thing. If bentonite, CMC, etc. doesn't work...then
> what? We have a very nice stable green glaze for the students, but it is
> difficult to keep that pesky green sand in suspension....
>
> Jonathan...how do you keep the copper carbonate in suspension?
> Suggestions????
>
> Sandy
>
>
> -----Original Message-----
> From: Jonathan Kirkendall [mailto:Jonathan@MIRIAMSKITCHEN.ORG]
> Sent: Thursday, October 17, 2002 12:20 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: copper carbonate
>
> Dan,
>
> I have copper carbonate from the same batch that you do - almost like very,
> very fine sand. I was completely dubious, but I have to say that I haven't
> seen an impact on my glazes. Even though after much stirring and after the
> application I find what I would consider to be suspiciously large amounts of
> the copper carb hanging out and gossiping in the bottom of the bucket, my
> glazes are still the same green as the last batch.
>
> Jonathan in DC
>
> -----Original Message-----
> From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
> Behalf Of Dan Bowen
> Sent: Thursday, October 17, 2002 8:19 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: copper carbonate
>
>
> The copper carbonate I recently recieved was a darker green
> than previous. From the archives I understand the paler version
> (powder like) which I have the most experience is hydrated and is more
> unpredictable with less copper. The darker green is more dence(granular)
> and goes to the bottom of my glaze bucket. I have experimented with CMC,
> bentonite and flocs. I do not have a ball mill. How do keep it in
> suspention or do I need to find a suplier with the lighter green color.
> Thanks
> Dan Bowen
> Eastville Virginia
> East of the Chesapeake Bay
>
> ____________________________________________________________________________
> __
> 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.
>
> ____________________________________________________________________________
> __
> 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.
>
> ______________________________________________________________________________
> 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.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Ababi on fri 18 oct 02
Stir
This is the magic word!
Ababi
---------- Original Message ----------
>Dan/Jonathan/Claybuds...
>I just got off the phone with the person who manages our studio and we were
>talking about this very thing. If bentonite, CMC, etc. doesn't work...then
>what? We have a very nice stable green glaze for the students, but it is
>difficult to keep that pesky green sand in suspension....
>Jonathan...how do you keep the copper carbonate in suspension?
>Suggestions????
>Sandy
>-----Original Message-----
>From: Jonathan Kirkendall [mailto:Jonathan@MIRIAMSKITCHEN.ORG]
>Sent: Thursday, October 17, 2002 12:20 PM
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: copper carbonate
>Dan,
>I have copper carbonate from the same batch that you do - almost like very,
>very fine sand. I was completely dubious, but I have to say that I haven't
>seen an impact on my glazes. Even though after much stirring and after the
>application I find what I would consider to be suspiciously large amounts of
>the copper carb hanging out and gossiping in the bottom of the bucket, my
>glazes are still the same green as the last batch.
>Jonathan in DC
>-----Original Message-----
>From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
>Behalf Of Dan Bowen
>Sent: Thursday, October 17, 2002 8:19 AM
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: copper carbonate
>The copper carbonate I recently recieved was a darker green
> than previous. From the archives I understand the paler version
>(powder like) which I have the most experience is hydrated and is more
>unpredictable with less copper. The darker green is more dence(granular)
>and goes to the bottom of my glaze bucket. I have experimented with CMC,
>bentonite and flocs. I do not have a ball mill. How do keep it in
>suspention or do I need to find a suplier with the lighter green color.
>Thanks
>Dan Bowen
>Eastville Virginia
>East of the Chesapeake Bay
>____________________________________________________________________________
>__
>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.
>____________________________________________________________________________
>__
>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.
>______________________________________________________________________________
>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.
Ilene Mahler on fri 18 oct 02
There are 2 ways ..1.put liquid dishwasher Detergent in the water or 2..use
cmc with really hot water..Ilene in Conn
----- Original Message -----
From: Dwiggins, Sandra (NIH/NCI)
To:
Sent: Thursday, October 17, 2002 1:07 PM
Subject: Re: copper carbonate
> Dan/Jonathan/Claybuds...
> I just got off the phone with the person who manages our studio and we
were
> talking about this very thing. If bentonite, CMC, etc. doesn't
work...then
> what? We have a very nice stable green glaze for the students, but it is
> difficult to keep that pesky green sand in suspension....
>
> Jonathan...how do you keep the copper carbonate in suspension?
> Suggestions????
>
> Sandy
>
>
> -----Original Message-----
> From: Jonathan Kirkendall [mailto:Jonathan@MIRIAMSKITCHEN.ORG]
> Sent: Thursday, October 17, 2002 12:20 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: copper carbonate
>
> Dan,
>
> I have copper carbonate from the same batch that you do - almost like
very,
> very fine sand. I was completely dubious, but I have to say that I
haven't
> seen an impact on my glazes. Even though after much stirring and after
the
> application I find what I would consider to be suspiciously large amounts
of
> the copper carb hanging out and gossiping in the bottom of the bucket, my
> glazes are still the same green as the last batch.
>
> Jonathan in DC
>
> -----Original Message-----
> From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
> Behalf Of Dan Bowen
> Sent: Thursday, October 17, 2002 8:19 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: copper carbonate
>
>
> The copper carbonate I recently recieved was a darker green
> than previous. From the archives I understand the paler version
> (powder like) which I have the most experience is hydrated and is more
> unpredictable with less copper. The darker green is more dence(granular)
> and goes to the bottom of my glaze bucket. I have experimented with CMC,
> bentonite and flocs. I do not have a ball mill. How do keep it in
> suspention or do I need to find a suplier with the lighter green color.
> Thanks
> Dan Bowen
> Eastville Virginia
> East of the Chesapeake Bay
>
>
____________________________________________________________________________
> __
> 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.
>
>
____________________________________________________________________________
> __
> 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.
>
>
____________________________________________________________________________
__
> 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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