kosmas g ballis on wed 6 aug 97
Dear Clayarters,
I am curious to see what some of the viewpoints are on the use of
leaded glaze on sculptural/ non-functional clayware. There seems to
be a lot on the subject of functional ware; of course, where food
and it's consumer comes in contact, but not too much on its application
in the non-functional...
I've researched plenty... But I would like some opinions...
Thanks for the discussion!
Kosmas Ballis
cobbeldi on thu 7 aug 97
Kosmas--we used lead in glazes way back in my college days (mid-70's).
Lead can produce some very beautiful and unusual glazes. My question is
this--given the toxicity of lead to the potter, why would you want to
expose yourself to the hazards? If I knew then what I know now, I would
never have used the stuff. No matter how clean I am in the studio,
clay/glaze dust leaves its imprint on everything, so it would stand to
reason that if I used lead in my glazes, lead dust would also float around
the studio. I would think that the cost for building a sterile room just
for lead glazes would be out of the range of most potters. So I guess what
I am trying to say is that for my own health I would want to avoid lead in
glazes on non-functional pieces.
Debra in Alabama
----------
> ----------------------------Original message----------------------------
> Dear Clayarters,
> I am curious to see what some of the viewpoints are on the use of
> leaded glaze on sculptural/ non-functional clayware. There seems to
> be a lot on the subject of functional ware; of course, where food
> and it's consumer comes in contact, but not too much on its application
> in the non-functional...
> I've researched plenty... But I would like some opinions...
> Thanks for the discussion!
> Kosmas Ballis
>
Bill Aycock on thu 7 aug 97
Actually, in this case, as in early industrial pottery in England- the main
problem is the danger to the one doing the work, not to the user/viewer.
Pb compounds (white lead is probably the WORST) are hard to control, and
their dust (when making the glazes) is BAAAAD. I had a cat (many years
ago) that slept on top of a bag, in the storage area, that had dust. The
vet saved him, using BAL, but it was touchy.
The additional danger area, that most people dont realize, is that the Pb
glazes tend to Fume (Volatalize) at any firing temperature most of us use.
The fumes get out, and the dust lands everywhere. The lead compounds coat
the kiln walls, tend to degrade the elements, and can come out of the kiln
later, when it is fired again, even though there is no Pb in the new firing.
Monona will probably jump in here, and anything she is likely to say will
be mild, compared to my opinion of the danger.
Bill- ranting away , on Persimmon Hill where there are no Pb compounds in
the shop-studio, even frits, (that I know of).
At 08:31 AM 8/6/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Dear Clayarters,
> I am curious to see what some of the viewpoints are on the use of
>leaded glaze on sculptural/ non-functional clayware. There seems to
>be a lot on the subject of functional ware; of course, where food
>and it's consumer comes in contact, but not too much on its application
>in the non-functional...
> I've researched plenty... But I would like some opinions...
> Thanks for the discussion!
>Kosmas Ballis
>
>
Bill Aycock --- Persimmon Hill --- Woodville, Alabama, US 35776
--- (in the N.E. corner of the State) ---
also -- W4BSG -- Grid EM64vr
baycock@hiwaay.net
Lauren Ball on thu 7 aug 97
I am curious to see what some of the viewpoints are on the use of
leaded glaze on sculptural/ non-functional clayware.
Kosmas Ballis
The problem with Lead glazes is that they are hazardous to the =
potter/sculptor. Few of us have the ability to maintain the required clean
rooms to prevent contamination. Even small amounts of contamination are =
serious because they are cumulative. Personally I would like to make
Lead glazed ware and donate it to politicians. But even the fumes given off=
during firing are hazardous, and will attach Lead to the next
batch of pots. The fumes can also leak out of a kiln and contaminate the =
studio. If you have an outdoor fired kiln, the Lead will attach
itself to smoke particles and settle out in your garden. It's just too =
risky. I personally don't even trust frit's unless used under strict
control with constant monitoring of the studio environment.
Lauren
Barbara Lewis on thu 7 aug 97
Kosmas: I am not an expert on the use of lead, but I know of a situation
that had dreadful results. When working with lead, it appears that you have
to be very careful when glazing and firing the work. Hazards of lead
exposure are not only limited to ingestion from glaze leaching. A clay
artist in the southeastern part of the country was producing mass quantities
of slip cast work for sale at Wal-Mart. . . She got pregnant and had some
routine blood work done. Her lead exposure level was in the highest
category, she should have been near dead. They couldn't chelate her (to try
to remove some of the lead) because she was pregnant. Her baby was born
physically okay, but at the age of 5 she is having learning disabilities and
major problems with impulse control. The clay artist has alzheimers-like
symptoms and is no longer able to do her work. There is a suit against the
manufacturer of the glaze because labeling was not accurate. When testing
the glaze they found that it had a higher lead content that had been
advertised in the literature and the label. The woman had been spraying her
glazes. Anyway, she is in extremely bad shape -- brain damage, severe
depression, and MS-like symptoms as well. The lead attaches to the long
bones in the body and even though lead is being chelated from her blood, the
bones continue to release lead. A tragedy. This information I have given
is reliable. Barbara
At 08:31 AM 8/6/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Dear Clayarters,
> I am curious to see what some of the viewpoints are on the use of
>leaded glaze on sculptural/ non-functional clayware. There seems to
>be a lot on the subject of functional ware; of course, where food
>and it's consumer comes in contact, but not too much on its application
>in the non-functional...
> I've researched plenty... But I would like some opinions...
> Thanks for the discussion!
>Kosmas Ballis
>
Ron Roy on fri 8 aug 97
I agree with most of the points made by other posters on this subject.
Lead glazes (including those made with lead frits) always volatilize, to
some degree, and the lead condenses onto surfaces inside the kiln as it
cools. This does mean it can re-volatilize during subsequent firings. My
point is - if you are making any functional work and firing it in that kiln
that ware will be contaminated to some degree - as mentioned by others. If
you are doing functional work you need an uncontaminated kiln to fire it
in.
I should mention as well the Canadian laws are being updated to conform
with American laws: Ware which can be used to contain food must be able to
pass lead leaching tests - those that can't must be labeled (block capital
letters 3mm high) permanently - DANGER - CONTAINS LEAD - DO NOT USE FOR
FOOD and in the Canadian version - in both official languages.
The alternative to the above is to have a design feature which makes it
unusable for food - like a hole or mounting hook.
Same deal for Cadmium.
So if the sculptural work can be used for food - lets say a decorative
platter - then the law applies.
>----------------------------Original message----------------------------
>Dear Clayarters,
> I am curious to see what some of the viewpoints are on the use of
>leaded glaze on sculptural/ non-functional clayware. There seems to
>be a lot on the subject of functional ware; of course, where food
>and it's consumer comes in contact, but not too much on its application
>in the non-functional...
> I've researched plenty... But I would like some opinions...
> Thanks for the discussion!
>Kosmas Ballis
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Fay & Ralph Loewenthal on fri 8 aug 97
Are Cadmium glazes volatilized at below 750C? I am
doing some testing with these glazes on glass. They are
melting and look terrific, but is it safe to be around the
kiln while firing? Gosh I hope I am not fumigating myself.
Ralph in PE SA
Ron Roy on sat 9 aug 97
Hi Ralph,
My library has failed me on this one but you are wise to be concerned - it
does but I don't know where or when.
I can say though - you are way braver than I to use it.
If you are fumigating yourself look for flue like symtoms - and worse.
>----------------------------Original message----------------------------
>Are Cadmium glazes volatilized at below 750C? I am
>doing some testing with these glazes on glass. They are
>melting and look terrific, but is it safe to be around the
>kiln while firing? Gosh I hope I am not fumigating myself.
>Ralph in PE SA
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
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