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food safe ware? - leaching

updated fri 14 may 04

 

Lee Love on tue 11 may 04


mailtoandrew@FSMAIL.NET wrote:

>I am puzzled why some have not only refused to acknowledge that dangers do
>exist but also criticise those who wish to discuss it, and hopefully
>learn.
>
>
I am puzzled too, because I haven't read any arguments on ClayArt
where folks say that "dangers do not exist." We just have different
ways of approaching the issue.

Actually, it sounds as if YOU are promoting the use of lead
in glazes, as long as they don't leach.


I would tell folks (everyone except our glass expert Karl
Platt of course ;-) ) not to use lead in their glazes, period. As the
saying goes: Garbage in, garbage out.


The other area you are overlooking is that there is no way
what we do with our glazes is going to effect what everyone else does
with their glazes. The only way to help protect the public from
these third world pots is through education about traditional pottery
and their proper uses. As the old saying goes:

"It is better to wear a pair of
shoes on than to cover the entire world with shoe leather."

Education and knowledge is much more effective than fear.


--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ Commentary On Pottery

mailtoandrew@FSMAIL.NET on tue 11 may 04


Hello Lee,

The only type of glaze I am promoting are those that are safe.

How do you conclude that I was promoting lead? My first post simply noted
a recent case of lead poisoning from the use of ceramic ware whilst my
second never mentioned the element. Lead may be the most infamous but the
leaching of other metals can also be hazardous.

And yes there have been posts where the dangers of metal release have been
dismissed. Equally worryingly is the criticism that has been levelled at
those wishing to discuss the subject.

It is possible for safe glazes to be formulated using lead compounds if
they have been properly formulated and fired. However in the absence of
understanding, trusted raw materials, tight production controls and
adequate testing materials that may present dangers to the maker or end
user should be avoided.

Why the statement about third world pots? There are some very skilled and
knowledgeable makers in the developing world whilst bad glazes are being
made in the developed countries. Whilst not directed at yourself there
does seem have been an occasional undercurrent of nationalistic arrogance
when this subject has been discussed, such as comments that its just about
Mexican pottery.

The potential for harm is not restricted to traditional ware or pots made
in any particular country. It exists from bad glazes, examples having been
found across the globe.

Your comment ... there is no way what we do with our glazes is going to
effect what everyone else does with their glazes ... This does not prevent
or exclude us from using safe glazes.

Education and knowledge is certainly the key but not of the end users who
expect and deserve safe products. It is the makers who must provide ware
that does not present health hazards. The information and knowledge to
achieve this is available ... books, lectures, magazine articles,
discussions on ClayArt.

Regards,

Andrew

Ron Roy on tue 11 may 04


So - 95% of the worlds population knows nothing about how durable any given
glaze is - only that they like the way it looks and/or - if it's on a
functional pot it must be safe.

So how long will it take to educate the rest of the world? Who will do the
educating? And what should potters do in the meantime - besides just keep
on doing what comes naturally?

RR


> The other area you are overlooking is that there is no way
>what we do with our glazes is going to effect what everyone else does
>with their glazes. The only way to help protect the public from
>these third world pots is through education about traditional pottery
>and their proper uses. As the old saying goes:
>
> "It is better to wear a pair of
>shoes on than to cover the entire world with shoe leather."
>
> Education and knowledge is much more effective than fear.

>Lee in Mashiko, Japan http://mashiko.org

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

Stacey Mc Dorman on tue 11 may 04


Sometimes we think that since we have fired to the correct temps that our glazes are safe. Unfortunately thi sisn't true. To check your own wares in a simple and cheap way, leave a slice of fresh lemon on the glaze overnight. If there is any discoloration then it isn't a safe glaze to clay combo/firing temp or materials need adjustment. You can also soak a piece or test tile in vinegar overnight for another variation on the leaching test.
--

--------- Original Message ---------

DATE: Tue, 11 May 2004 19:51:27
From: Ron Roy
To: CLAYART@LSV.CERAMICS.ORG
Cc:

>So - 95% of the worlds population knows nothing about how durable any given
>glaze is - only that they like the way it looks and/or - if it's on a
>functional pot it must be safe.
>
>So how long will it take to educate the rest of the world? Who will do the
>educating? And what should potters do in the meantime - besides just keep
>on doing what comes naturally?
>
>RR
>
>
>> The other area you are overlooking is that there is no way
>>what we do with our glazes is going to effect what everyone else does
>>with their glazes. The only way to help protect the public from
>>these third world pots is through education about traditional pottery
>>and their proper uses. As the old saying goes:
>>
>> "It is better to wear a pair of
>>shoes on than to cover the entire world with shoe leather."
>>
>> Education and knowledge is much more effective than fear.
>
>>Lee in Mashiko, Japan http://mashiko.org
>
>Ron Roy
>RR#4
>15084 Little Lake Road
>Brighton, Ontario
>Canada
>K0K 1H0
>Phone: 613-475-9544
>Fax: 613-475-3513
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
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>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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May Luk on wed 12 may 04


Hiya;

I read the letter in Ceramic Review. The editor did not mentioned the BS486=
0
or the Health and Safety Executive [www.hse.gov.uk] It's a shame. The reade=
r
was asked to look up lead glaze on textbook. Nobody was reminded that those
textbook might be outdated.

I'm aware of the Metal Release Limit in Britain [thanks to Janet Kaiser and
by reading clayart] I found a lab who does it in Stoke on Trent. It's =A318 a
test BTW. [If export to the states, 6 tests for each style for FDA, and
extra 6 test for each style to go to California] However, this law is not
imposed on all ware made with Cadmium and Lead, not for the small
productions anyways. It's not like in the States where they make random tes=
t
on wares.

In schools, most students do not know about this. Most of the community
college students/adult learners are people who enjoy working in clay. They
don't know what's in the glaze and they don't care. They treat it as if it'=
s
just paint to decorate the pots. They know a bit of health and safety [ie;
work wet, no food or drinks in the studio], they don't have the opportunity
to encounter hazard as they know it. Then they feed their kids food with
their earthenware or they give the pots away to the in-laws. I have a few
first earthwares that I made - lead frit tin glaze loaded with copper. And
Raku glaze all made with lead bisilicate. [I do love lead glaze though. I'd
make it if I have the right situation]

Most potters here I know *mix* glaze, they don't formulate glaze. They have
recipes from books/teachers/school that they mix. They alter the recipe if
they are experienced. The word 'recipe' sets people's mindset in a certain
direction. Chemistry is a big scary word. To talk about it is like showing
off.=20

I just read an article on encapsulated red stain being food safe. The write=
r
described the process in making it, thus, no cadmium left in the stain. I
know the person who wrote it. He's a nice man. He probably got the
information from the manufacturer. I'm not sold though. If there's no
cadmium left, where's the red come from? I think it's marketing. Little
reading that I did, I know that a lot of stuff goes on in the kiln in such
high heat.=20

There are many informations out there - in bits and pieces. They are all
very vague: Like: badly formulated glazes are susceptable to acid solutions
such as tea, fruit juice and so on...[partial quote ceramic review] But
where is the action plan?

Only in MC6G, where I found easy to follow step-by-step intructions on how
to test and formulate stable glaze, but you all know that. :-)))

Regards
May
London UK

mailtoandrew@FSMAIL.NET on wed 12 may 04


Hello Stacey,

With the lemon, or vinegar, test being simple and easy it is worth
recommending.

However whilst discoloration suggests problems exist the lack of it does
not demonstrate a safe glaze. It is an indicative rather than definitive
procedure.

Regards,

Andrew

Ron Roy on wed 12 may 04


So - every potter should know the difference between a durable and an
unstable glaze.

How many potters do you know who can tell the difference.

If we are to do the educating then it is time we became educated.

Who is going to educate the potters?

So every shop keeper must have to know as well?

And how do we deal with those who don't know and don't care?


RR


>>And what should potters do in the meantime - besides just keep
>>on doing what comes naturally?
>>
> Take responsibility! Every potter an educator!
>
>--
>Lee in Mashiko, Japan http://mashiko.org
>http://potters.blogspot.com/ Commentary On Pottery

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513

wayneinkeywest on wed 12 may 04


If they will not be educated, then they will at least make a great
organic additive to the next few batches of clay.
Sorry if that sounds harsh, but in this country (US) at least, there
is no longer any excuse for ignorance, as any of 200,000 product
liability suits has proven.

Where did i put that shovel.....
Wayne Seidl
Key West, Florida, USA
North America, Terra
Latitude 81.8, Longitude 24.4
Elevation 3.1 feet (1m)
----- Original Message -----
From: "Ron Roy"
To:
Sent: Wednesday, May 12, 2004 9:25 PM
Subject: Re: Food safe ware? - leaching



> And how do we deal with those who don't know and don't care?
>
>
> RR

Ivor and Olive Lewis on thu 13 may 04


Dear Wayne,
What would the legal profession do for a living without the
proliferation of ignorance.
Best regards,
Ivor Lewis. Redhill, South Australia
<<, there is no longer any excuse for ignorance, as any of 200,000
product liability suits has proven. >>

Lee Love on thu 13 may 04


Ron Roy wrote:

>And what should potters do in the meantime - besides just keep
>on doing what comes naturally?
>
Take responsibility! Every potter an educator!

--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ Commentary On Pottery

Lee Love on thu 13 may 04


mailtoandrew@FSMAIL.NET wrote:

>
>that does not present health hazards. The information and knowledge to
>achieve this is available ... books, lectures, magazine articles,
>discussions on ClayArt,
>
>

I assumed that because the title of the post is about leaching,
that you would approve of a lead glaze that didn't leach. As Karl
Platt has explained to us, this is possible.

My personal solution is to not use lead in my glazes.


--
Lee in Mashiko, Japan http://mashiko.org
http://potters.blogspot.com/ Commentary On Pottery