Bun Bun on sun 18 may 03
Does anyone know how to use the raw mineral Galena in a glaze?
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Earl Brunner on sun 18 may 03
Galena is or contains lead. Who do you want to kill?
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bun Bun
Sent: Sunday, May 18, 2003 6:32 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Lead Glazes?
Does anyone know how to use the raw mineral Galena in a glaze?
_________________________________________________________________
J. B. Clauson on sun 18 may 03
Galena is lead ore - which means it is primarily lead with a lot of other
materials mixed in. How you use this material in a glaze (assuming you
would use lead) would depend on the other minerals contained in the ore. If
you insist on using it, you could have a laboratory analyze it for you and
then do your calculations. Or, you could do it by guess and by golly with
experimentation.
Just don't use it near me or near any children and any sane adults! If you
do glaze with this material, be sure to mark the ware "Not food safe. Glaze
contains lead".
Seriously, lead poisoning is a sneaky, insidious b------! It first robs you
of your energy, then you IQ eventually leading to irreparable brain damage
and will eventually rob you of your life. We potters have been taking the
rap for the fall of the Roman Empire for centuries because of the lead
glazes so popular during that period (So, who knew back then?). Yes, it
produces beautiful reds - but at what price!
Jan C.
Janet Kaiser on mon 19 may 03
Errr.... Do you really want to know, Bun Bun? I mean, is this a
hypothetical, historical question or do you really propose using it? Are
you looking to provocate, because the mere mention of lead will make some
people faint around here! Although it occurs in everywhere around the
world, I am faintly surprised you have access to it as a commodity, unless
you are located in a country where it is still in common use? Or have
inherited an old country pottery with ancient bags full of Galena still
hanging around?
From a UK point of view we can only talk in historical terms. I believe the
last raw lead sources disappeared from supply lists in the 1960s. It
heralded the end of a long tradition. Medieval potters used Galena in
(mostly) once-fired, low temperature work. Lead is a flux and fused with
the clay to produce a glaze. It would "eat" any thin layers of slip from
the decoration and you can see this in some museum pieces if you look
carefully.
Otherwise it was in combinations such as 95% lead and 5% clay. All my
earthenware recipes call for lead bi or trisillicate, but only because I am
a dinosaur. Nobody used Lead Carbonate or White Lead even then, nor Red
Lead, Galena (lead sulfide) or Lithage (lead monoxide?) although the
impurities could add depth to the glazes which we were no longer achieving
with the sillicates. The disappearance of lead was one factor in the
upsurge of interest in stoneware glazes, such as Celadons and the dreaded
Dolomite, which was really the "in" glaze here back then. Lots of pretty
matt pinks and mauves! A far cry from the "honey" and browns of the
traditional lead "country pottery" glazes associated with earthenware...
Michael Cardew started out at Winchcombe using Galena... The local doctor
apparently used to check the workers once a month -- for lead poisoning.
They would show their teeth. If the gums were black they would have had
lead poisoning, which is irreversible. Ray Finch (a Cardew pupil) told me
all this at Aberystwyth in 2001.
Once lead poisoning is so advanced as to produce black gums, you just about
have time to arrange your own funeral. Glazers in The Potteries only lived
a few months from the day they took that job. Everyone knew they were
signing their own death warrant... Excellent wages of course.
Which is why I am not going to impart my limited knowledge. Yes, I know how
to use Galena, have recipes and firing temperatures etc., BUT it would not
be very public spirited of me to tell you. Do not be cross, but I do not
think it would do you or anyone else a service.
Sincerely
Janet Kaiser
*** IN REPLY TO THE FOLLOWING MAIL:
>Does anyone know how to use the raw mineral Galena in a glaze?
*** THE MAIL FROM Bun Bun ENDS HERE ***
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TRUTH is too precious to tell every fool who asks for it...
****** This post was sent to you today by Janet Kaiser *******
The Chapel of Art / Capel Celfyddyd
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Tel: ++44 (01766) 523570 URL: http://www.the-coa.org.uk
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Janet Kaiser on mon 19 may 03
Yes, Earl! Not "contains" though. Galena IS lead.
A lead ore : Lead Sulfide : PbS
Although it contains impurities such as copper and silver.
Only slightly less toxic than Lithage or White Lead.
We used to have open sacks of the stuff in college back in the olden
days... Even then it was not being used because we were all into stoneware,
but we used to sweep it back and into the sacks whenever they fell over...
Sincerely
Janet Kaiser
*** IN REPLY TO THE FOLLOWING MAIL:
>Galena is or contains lead. Who do you want to kill?
*** THE MAIL FROM Earl Brunner ENDS HERE ***
**********************************************************************
TRUTH is too precious to tell every fool who asks for it...
****** This post was sent to you today by Janet Kaiser *******
The Chapel of Art / Capel Celfyddyd
8 Marine Crescent, Criccieth LL52 0EA, Wales, UK
Tel: ++44 (01766) 523570 URL: http://www.the-coa.org.uk
**********************************************************************
claybair on tue 20 may 03
In a previous thread on lead glazes someone
brought up the issue of lead contamination in the kiln.
If I recall correctly there was never an answer as to how
long it would take to eliminate it. Anyone?
Gayle Bair
Bainbridge Island, WA
http://claybair.com
Sabine Wolf on tue 20 may 03
> From a UK point of view we can only talk in historical terms. I believe
the
> last raw lead sources disappeared from supply lists in the 1960s. It
> heralded the end of a long tradition. Medieval potters used Galena in
> (mostly) once-fired, low temperature work. Lead is a flux and fused with
> the clay to produce a glaze. It would "eat" any thin layers of slip from
> the decoration and you can see this in some museum pieces if you look
> carefully.
I have a glaze book, just a few years old, with some recipes with more lead
than lead monosilicate can give you, so the recipes use Pb3O4 (mennige), a
powder with a orange-red colour. And it was not such a huge problem to get
this stuff here in the town (Berlin). I know three ceramic suppliers here,
the one sells you lead silicates only if you bring the proof that you have
a business due to legal reasons, the second does the some and sells you lead
silicates only in 50kg bags but the third, a pottery division of a hobby
craft store has thing like Pb3O4 (not officially anymore, but I saw it on
the shelf) and rather seldom used oxides like antimony oxide, so I bought
100g of Pb3O4,100g antimony oxide and 1 kg lead mono silicate without any
qestions, the only thing I had to do was to write my name and my adress in a
poison book. 100g is not much, I bought it more for the completeness of my
material collection than to produce a lot of glazes out of Pb3O4.
Tschau,
Sabine
Edouard Bastarache on tue 20 may 03
Hello Gayle,
35 years ago, I learned that firing the kiln 3 times above the
volatilization temperature of lead on 3 different days
was the thing to do to rid the contaminated kiln of
lead.
Naturally, good ventilation during the process is
mandatory, and keep out of the kiln room.
Later,
"Ils sont fous ces Quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
----- Original Message -----
From: claybair
To:
Sent: Tuesday, May 20, 2003 12:23 PM
Subject: Re: Lead Glazes?
> In a previous thread on lead glazes someone
> brought up the issue of lead contamination in the kiln.
> If I recall correctly there was never an answer as to how
> long it would take to eliminate it. Anyone?
>
> Gayle Bair
> Bainbridge Island, WA
> http://claybair.com
>
>
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