Bill Edwards on sun 4 jan 04
I made a statement to such in regards to other
chemicals beig used without having any clue as to what
it is or how to use it, just follow whatever a recipe
says and it must be ok. We can use those product
information sheets and MSDS sheets at every level of
use if we compound materials at all. IMHO
The only way you will convince anyone who has made
their minds ups about what they know and what they do
is to physically test it, have professional opinions
in writting and the method of testing used and the
amount of extraction or materials found during
testing.
I would then send this information and all my
statements to the person responsible as well as their
employers and if they have a commitee who makes
decisions, a copy needs to go there with all the
details and a request in writing for payment.
Make sure you are getting a real positive result from
a lab using certifiable techniques first. They are
often some mis-leading things that happen with home
tests but its a good way to at least get the
information you need to help make such a decision.
You have made it rather clear to the person who has
decided to continue on, so whats left is factual
reporting and responsibility through records that
reflect the found results.
http://www.deh.gov.au/atmosphere/airquality/lead/ceramics.html
claybair
Subject: Continuing saga - A safe leaded glaze?
Bill Edwards
=====
http://www.geocities.com/tallapoosarivergallery/index.html (Coming soon)
http://www.tallapoosariverpottery.com/
"Anyone whose panties get in a bunch over what I have to say from my
tiny corner oughta order some bigger roomier panties....!" A candle for Arti
Bill Edwards
PO Box 367
Camp Hill, Alabama. 36850
__________________________________
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Paul Lewing on mon 21 nov 11
On Nov 21, 2011, at 3:15 PM, Eva Gallagher wrote:
Hi - I think because of its very low melting point, 621F, I think you
will
always get lead fumes even at cone 018 -not as much as in 05 but still
some
that will then condense on the rest of the pot. I thought that old kilns
that were used for eathernware often would have lead on the insides that
would volatilize and recondense on whatever was in the kiln every time
it as
fired.
That's true if the lead has not been fritted. Fritted lead does not
volatilize at china paint temperatures. I forget which source book I
found that information in when I was researching my book, but I know
it to be true. I tested some of my kiln furniture that has been in
more than a thousand china paint firings, and there is no trace of
lead on them.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
Paul Lewing on mon 21 nov 11
On Nov 21, 2011, at 3:34 PM, John Britt wrote:
Here is a post from Edouard in the archives - on fumes :
Basic lead carbonate (C2H2O8Pb3) is unstable under the following
conditions : if heated it decomposes at 400 C and emits lead monoxide,
carbon monoxide and carbon dioxide.
Red lead (Pb3O4)) is unstable under the following conditions : if
heated to decomposition (over 500 C), there is release of oxygen and
emission of toxic fumes of lead.
Yellow lead ((Pb) is unstable under the following conditions: if
heated at 300-400 C it transforms into lead tetraoxide.
None of those are used in china paints.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
Rimas VisGirda on mon 21 nov 11
Lili had posted something a few days ago regarding lead in majolica glazes =
that I started to reply to and got sidetracked, I thought her post was righ=
t on the money. Lead free overglazes and china paints also lack the luster =
and beauty of the leaded variety. The lead free paints typically need to be=
fired much hotter
and don't have the range of the leaded ones; they also tend to be flatter a=
nd not as smooth -from my experience with screening decals as well as
screening directly onto clay. -Rimas
Paul Lewing on mon 21 nov 11
On Nov 21, 2011, at 6:52 AM, Rimas VisGirda wrote:
Lili had posted something a few days ago regarding lead in majolica
glazes that I started to reply to and got sidetracked, I thought her
post was right on the money. Lead free overglazes and china paints
also lack the luster and beauty of the leaded variety. The lead free
paints typically need to be fired much hotter
and don't have the range of the leaded ones; they also tend to be
flatter and not as smooth -from my experience with screening decals as
well as
screening directly onto clay. -Rimas
Not only that, but I had several colors of one brand of lead free
china paints tested when I was writing my book, and they had lead in
them! I called the tech person for that company and she had no idea
why they would have tested positive for lead release. She also said
when I asked her if they now would have some tested since I had told
her that and she said no. They didn't have near the lead that regular
china paints have, but they did have some.
Rimas is right. Everyone agrees that the lead free china paints are
not as nice as the regular ones, and in fact, the older ones that have
more lead than the modern ones are even nicer. Too bad about that one
small issue with lead. Under about cone 4, it's the perfect ceramic
material in almost every way.
But I do need to say a couple of other things about lead in china
paints.
First, china paints are FAR less dangerous than lead glazes, for three
reasons. Number one: there's almost none of it there. Typically, you
are putting out china paint in quantities of less than a teaspoon, and
it's an incredibly thin layer on the work. Number two: there is no
dust. Number three: it does not volatilize in your kiln.
Since china paints have no stabilizer portion like other glazes
(they're meant to go on a fired glaze surface so they don't need
alumina to work with clay) that portion is taken up with more
colorant. While a glaze typically has less than 8% colorant, possibly
as high as 15% in the case of iron, china paints often have 20-40%
colorant. None of these heavy metals is exactly benign, so here's my
opinion about lead in china paint, and it's worth exactly what you're
paying for it.
Using lead free china paints to avoid exposure to lead is pointless.
Because of the other stuff that's in there, you're going to take all
the same precautions anyway, so why give up the good stuff?
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
Lee on mon 21 nov 11
On Mon, Nov 21, 2011 at 11:28 AM, Paul Lewing wrote:
> Using lead free china paints to avoid exposure to lead is pointless.
> Because of the other stuff that's in there, you're going to take all
> the same precautions anyway, so why give up the good stuff?
John Baymore corresponded with a tech at the manufacturer to figure
out which, that were not labeled "lead", actually had no lead. I
always forget which ones he came up with, but you could ask him.
--=3D20
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Paul Lewing on mon 21 nov 11
On Nov 21, 2011, at 11:55 AM, Lee wrote:
John Baymore corresponded with a tech at the manufacturer to figure
out which, that were not labeled "lead", actually had no lead. I
always forget which ones he came up with, but you could ask him.
I did. Different company.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
John Britt on mon 21 nov 11
Paul,
My thoughts are that you can't tell if lead glazes leach more than china =
=3D
painted=3D20
glazes unless you test them. Even though you only put on small amounts - =
=3D
you=3D20
are putting it directly on the surface, so if you are making functional w=
=3D
ork it is a=3D20
thin layer right where the food is.
Just my thoughts,=3D20
John Britt
Paul Lewing on mon 21 nov 11
On Nov 21, 2011, at 12:54 PM, John Britt wrote:
My thoughts are that you can't tell if lead glazes leach more than
china painted
glazes unless you test them. Even though you only put on small amounts
- you
are putting it directly on the surface, so if you are making
functional work it is a
thin layer right where the food is.
True, but there is just almost no material there in the china paint.
It's so thin you can se through it. There just isn't as much lead to
leach as there is with a lead glaze. And I always tell everyone, you
don't put it where it comes in contact with food.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
John Britt on mon 21 nov 11
Paul,
I am with you on the" no contact with food surfaces". Then there is no
worry for the consumer, only for the potter. But I will still argue
that even though there is a small amount in china paints, the fact
that the veneer is on the surface makes it more vulnerable to
leaching.
Take care,
John Britt
johnbrittpottery@gmail.com
http://ncclayclub.blogspot.com
www.johnbrittpottery.com
Eva Gallagher on mon 21 nov 11
Hi - I think because of its very low melting point, 621F, I think you will
always get lead fumes even at cone 018 -not as much as in 05 but still some
that will then condense on the rest of the pot. I thought that old kilns
that were used for eathernware often would have lead on the insides that
would volatilize and recondense on whatever was in the kiln every time it a=
s
fired.
Eva Gallagher
http://newfoundoutpotter.blogspot.com/
http://www.valleyartisans.com/gallagher/Gallagher.htm
Eva Gallagher
----- Original Message -----
From: "John Britt"
To:
Sent: Monday, November 21, 2011 3:54 PM
Subject: Re: get the lead out
Paul,
My thoughts are that you can't tell if lead glazes leach more than china
painted
glazes unless you test them. Even though you only put on small amounts - yo=
u
are putting it directly on the surface, so if you are making functional wor=
k
it is a
thin layer right where the food is.
Just my thoughts,
John Britt
John Britt on mon 21 nov 11
Here is a post from Edouard in the archives - on fumes :
Basic lead carbonate (C2H2O8Pb3) is unstable under the following
conditions=3DA0: if heated it decomposes at 400 C and emits lead monoxide,
carbon monoxide=3DA0and carbon dioxide.
Red lead (Pb3O4)) is unstable under the following conditions : if
heated to=3DA0decomposition (over 500 C), there is release of oxygen and
emission of=3DA0toxic=3DA0fumes of lead.
Yellow lead ((Pb) is unstable under the following conditions: if
heated at=3DA0300-400 C=3DA0it transforms into lead tetraoxide.
Later,
Edouard Bastarache=3DA0Irreductible Quebecois=3DA0Indomitable Quebeker
Sorel-Tracy=3DA0Quebec=3DA0edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
John
johnbrittpottery@gmail.com
http://ncclayclub.blogspot.com
www.johnbrittpottery.com
Eva Gallagher on mon 21 nov 11
So am still confused. So is lead monoxide a toxic lead fume or does the lea=
d
make it too heavy? And what form are the toxic fumes of lead from the red
lead - in the form of gaseous lead molecules or also lead monoxide?
Eva Gallagher
http://newfoundoutpotter.blogspot.com/
http://www.valleyartisans.com/gallagher/Gallagher.htm
---- Original Message -----
From: "John Britt"
To: "Eva Gallagher"
Cc:
Sent: Monday, November 21, 2011 6:34 PM
Subject: Re: get the lead out
Here is a post from Edouard in the archives - on fumes :
Basic lead carbonate (C2H2O8Pb3) is unstable under the following
conditions : if heated it decomposes at 400 C and emits lead monoxide,
carbon monoxide and carbon dioxide.
Red lead (Pb3O4)) is unstable under the following conditions : if
heated to decomposition (over 500 C), there is release of oxygen and
emission of toxic fumes of lead.
Yellow lead ((Pb) is unstable under the following conditions: if
heated at 300-400 C it transforms into lead tetraoxide.
Later,
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
John
johnbrittpottery@gmail.com
http://ncclayclub.blogspot.com
www.johnbrittpottery.com
John Britt on tue 22 nov 11
Paul,
Glad to hear about the testing of the kiln. I get questions a lot about d=
=3D
ecals and=3D20
china paints these days and glad to have some facts to pass on.
Thanks,
John
Des & Jan Howard on tue 22 nov 11
John
I can see how some lead compounds can "fume".
What is the situation with lead bisilicate frit &
glazes containing lead bisilicate frit?
Des
On 22/11/2011 10:34 AM, John Britt wrote:
> Here is a post from Edouard in the archives - on fumes :
> Basic lead carbonate (C2H2O8Pb3) is unstable under the following
> conditions : if heated it decomposes at 400 C and emits lead monoxide,
> carbon monoxide and carbon dioxide.
> Red lead (Pb3O4)) is unstable under the following conditions : if
> heated to decomposition (over 500 C), there is release of oxygen and
> emission of toxic fumes of lead.
> Yellow lead ((Pb) is unstable under the following conditions: if
> heated at 300-400 C it transforms into lead tetraoxide.
--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850
02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624
marci Boskie's Mama =3D^..^=3D on wed 23 nov 11
I may be thinking wrong about this since I dont do functional ware...
but arent liner glazes used , for example, on mugs where the glaze
on the outside is leachable. Quoted from the Digitalfire website:" It
is common to glaze food surfaces of utilitarian ware with a white or
transparent glaze called a 'liner glaze'. This is done to avoid
exposing in-glaze or on-glaze metallic colorants to food or drink
(which could leach them away). Liner glazes can be applied in such a
way that they meet the outer glaze at time rim. "
If this is the case, and it's acceptible to have a glaze on the
outside of a mug that will leach bad stuff as long as the glaze on
the inside is foodsafe, then I dont get the beef with china paints.
We dont paint the insides of mugs... only outside surfaces.. and on
pieces that are used for table service, the design is generally
confined to the outside edge . Pieces that are painted allover are
not intended for food. They are painted with the intention that the
piece is a canvas.
China paint is a great medium for painting. The translucence of the
fired paint allows for layered color effects that cant be gotten in
any other medium, even oils. ... and being able to add other effects
to the toolbox, like metallics, interference colors, lusters , glass
fusion etc allow us to obtain effects that cant be gotten by
painting in oil , watercolor, pastel etc.
marci the chinapainter
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