Jackson Gray on tue 2 dec 08
Hi there, I am hoping someone can help me understand the report I
received back from Brandywine Science Center (In case it hasn't been
mentioned recently, Alfred is no longer the place to do leaching tests).
I have a 8.31 mg/L copper leaching result from "analyses performed in
accordance with standard methods for examination of water and waste
water, 18th edition APHA-AWWA-WPCF"
I am assuming this is too high to accept for lining a functional pot,
but can someone please elaborate?
Thanks,
Jackson
John Hesselberth on wed 3 dec 08
Hi Jackson,
You are asking a question for which there is no definitive answer. The
most conservative answer would be to be guided by water standards
which are 1.3 mg/l. Personal opinion is that is way too conservative
although it is the level Monona Rossol recommends. She feels that in
lieu of better data we should be conservative. In our book we aimed
for 6.0 or less when the glaze contained 5% copper carbonate and 6%
rutile. Our logic in doing that was a balance between having wide
aesthetic choice, low leaching, and almost certain passing of the
vinegar test which I feel is a more practical and useful test. We also
knew if we could keep leaching of copper to less than 6, other
colorants would also leach very little.
So it is your choice. I would certainly do a vinegar test and not use
it for functional work if you get a color or sheen change. Or you
might choose to use that glaze on the outside of functional pots and
use a liner glaze on the inside. You will also find that lowering the
copper concentration a little might still give you a color you like
and that will definitely lower leaching.
Regards,
John
On Dec 2, 2008, at 10:35 PM, Jackson Gray wrote:
> Hi there, I am hoping someone can help me understand the report I
> received back from Brandywine Science Center (In case it hasn't been
> mentioned recently, Alfred is no longer the place to do leaching
> tests).
>
> I have a 8.31 mg/L copper leaching result from "analyses performed in
> accordance with standard methods for examination of water and waste
> water, 18th edition APHA-AWWA-WPCF"
>
> I am assuming this is too high to accept for lining a functional pot,
> but can someone please elaborate?
> Thanks,
> Jackson
John Hesselberth
http://www.masteringglazes.com
http://www.frogpondpottery.com
Taylor Hendrix on wed 3 dec 08
Curious what method they used. Did they give you the method numbers by
any chance? Shucks I don't have my copy of standard methods handy.
Taylor, in Rockport TX
wirerabbit1 on Skype (-0500 UTC)
http://wirerabbit.blogspot.com
http://wirerabbitpots.blogspot.com
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On Tue, Dec 2, 2008 at 9:35 PM, Jackson Gray wrote:
...
> I have a 8.31 mg/L copper leaching result from "analyses performed in
> accordance with standard methods for examination of water and waste
> water, 18th edition APHA-AWWA-WPCF"
...
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