John Hesselberth on fri 25 feb 00
------------------
Good News=21=21=21
There will be a discussion of metals leaching from glazes (glaze stability) =
at
NCECA after all=21
As a result of the generosity and interest in the subject by Linda Ketchum =
and
Howard Axner of Axner Pottery Supply, we have been offered the use of the =
Axner
Pottery Supply suite for this discussion from 2-4 pm on Thursday. Thank you
Howard and Linda=21
While I will encourage a discussion of the issue, I do plan to introduce it =
by
summarizing what is known and not known about the subject. Here is a rough
abstract of my view of how the discussion might go:
-----
While stability of lead-containing glazes to acids has been well-studied, =
there
has been very little work to understand how well other metals used in glazes
resist acid (in acidic foods) attack. Why should we care? After all, none =
of
the other metals we use in significant quantity are anywhere close to the
toxicity of lead. Further, there are no reported instances of anyone having
been harmed from leaching of metals from a lead-free glaze. There are at =
least
3 reasons we might care: 1) craftsmanship and suitability of our pottery =
for
its function, 2) potential future discovery of hazards as medical science
develops better diagnostic tools and 3) potters should not be in the =
business of
providing unintended metallic supplements to a person=B9s diet. Are there =
others?
What is your view on the importance of this subject?
To set the stage for this discussion, a very brief summary will be presented=
on
1) what is known about metals other than lead leaching from glazes, 2) a =
range
of views on what acceptable leaching levels might be, 3) some examples of =
glazes
similar in appearance which have very different leaching performance 4) some
prescreening tests any potter can perform to get an early indication of =
glaze
stability and 5) how to have your glazes inexpensively tested at Alfred
Analytical Laboratory.
-----
IF you have any test results you are willing to share, please bring them =
with
you (with an extra copy to give me). I still have only a few results, from =
work
other than my own, and I know quite a number of people are having glazes =
tested.
Please add any thoughts you might have on how to make this discussion as
valuable as possible to you.
Hope to see you there, John
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john=40frogpondpottery.com web site: http://www.frogpondpottery.com
=22It is time for potters to claim their proper field. Pottery in its pure =
form
relies neither on sculptural additions nor on pictorial decorations. but on =
the
counterpoint of form, design, colour, texture and the quality of the =
material,
all directed to a function.=22 Michael Cardew in =22Pioneer Pottery=22
Edouard Bastarache on sat 26 feb 00
------------------
-----Message d'origine-----
De : John Hesselberth =3Cjohn=40frogpondpottery.com=3E
=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Date : 25 f=E9vrier, 2000 17:43
Objet : Glaze Stability Discussion at NCECA
----------------------------Original message----------------------------
------------------
=22Further, there are no reported instances of anyone having
been harmed from leaching of metals from a lead-free glaze=22
Hello John,
I agree with you,
Last year i asked Quebec govt. toxicologists to search all the
databases they have access to in order to find cases
of intoxications from lead-free glazes and to my surprise
the answer was=22NONE=22.
Later,
Edouard Bastarache
Dans / In =22La Belle Province=22
edouardb=40sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/=7Eedouardb/
Ron Roy on thu 2 mar 00
Hi John,
This is wonderful news - good for Howard and Linda.
Perhaps the issue of glazes changing colour in use would be a an
appropriate subject for this disscussion.
RR
>----------------------------Original message----------------------------
>Good News!!!
>
>There will be a discussion of metals leaching from glazes (glaze stability) at
>NCECA after all!
>
>As a result of the generosity and interest in the subject by Linda Ketchum and
>Howard Axner of Axner Pottery Supply, we have been offered the use of the Axner
>Pottery Supply suite for this discussion from 2-4 pm on Thursday. Thank you
>Howard and Linda!
>
>While I will encourage a discussion of the issue, I do plan to introduce it by
>summarizing what is known and not known about the subject. Here is a rough
>abstract of my view of how the discussion might go:
>
>-----
>
>While stability of lead-containing glazes to acids has been well-studied, there
>has been very little work to understand how well other metals used in glazes
>resist acid (in acidic foods) attack. Why should we care? After all, none of
>the other metals we use in significant quantity are anywhere close to the
>toxicity of lead. Further, there are no reported instances of anyone having
>been harmed from leaching of metals from a lead-free glaze. There are at least
>3 reasons we might care: 1) craftsmanship and suitability of our pottery for
>its function, 2) potential future discovery of hazards as medical science
>develops better diagnostic tools and 3) potters should not be in the
>business of
>providing unintended metallic supplements to a person's diet. Are there
>others?
>What is your view on the importance of this subject?
>
>To set the stage for this discussion, a very brief summary will be presented on
>1) what is known about metals other than lead leaching from glazes, 2) a range
>of views on what acceptable leaching levels might be, 3) some examples of
>glazes
>similar in appearance which have very different leaching performance 4) some
>prescreening tests any potter can perform to get an early indication of glaze
>stability and 5) how to have your glazes inexpensively tested at Alfred
>Analytical Laboratory.
>
>-----
>
>IF you have any test results you are willing to share, please bring them with
>you (with an extra copy to give me). I still have only a few results,
>from work
>other than my own, and I know quite a number of people are having glazes
>tested.
>
>Please add any thoughts you might have on how to make this discussion as
>valuable as possible to you.
>
>Hope to see you there, John
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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