Rimas VisGirda on thu 24 nov 11
=3D0A=3D0AI'm thinking the key-word here is leaching... When lead is in a s=
tabl=3D
e glaze matrix as in glaze or overglaze (which is actually a very, very, ve=
=3D
ry low fire glaze) it won't leach unless attacked by a VERY strong acid, wh=
=3D
ich would tend to decompose (leach) any material it was brought in contact =
=3D
with. Now, if lead is present in a stable glaze matrix, it won't leach out;=
=3D
the some 30 year old test being to put vinegar or lemon juice or orange ju=
=3D
ice in contact with the suspect piece and see if there is "scumming" at the=
=3D
interface, indicating that the (weak) acid is breaking down the glaze and =
=3D
releasing the constituents of the glaze (which might include lead) as in un=
=3D
derfired ware from Mexico which started the frenzy in the 70's to my recoll=
=3D
ection. If I'm not mistaken we eat off of lead glazed items all the time, s=
=3D
uch as restaurant ware at our favorite diner. Correct me if I am wrong, but=
=3D
"testing for lead" is a measure of the lead released under certain=3D0Acon=
di=3D
tions of=3D0Ause and not of the actual lead content in the item. Isn't that=
w=3D
hy industry tests its products to determine if it is stable or if it will "=
=3D
release" lead? So let's consider the maker and the user. The maker, individ=
=3D
ual potter or industry, should be careful with the use of the raw material,=
=3D
lead, as it can be harmful to its workers. The user however should have no=
=3D
fear of lead bearing glazes IF THEY ARE LOCKED INTO A STABLE GLAZE MATRIX,=
=3D
the only problem comes if the glaze is underfired... Now, if a glaze conta=
=3D
ins lead and is in a stable glaze matrix, the consumer CAN consume some of =
=3D
that lead over years of using that dish, especially if the consumer is a ca=
=3D
rnivore as the slicing of the meat against the plate will wear=3D0Aaway som=
e =3D
glaze (or overglaze decoration, as in decal decorated or handpainted ware) =
=3D
much like the soles of our shoes wear away from walking. But my hypothesis =
=3D
is, that amount of lead ingested by slicing ones steak is so insignificant=
=3D
=3D0Astatistically that=3D0Ait makes the whole discussion moot...=3D0A=3D0A=
=3D0ADate:=3D
=3DA0 =3DA0 Mon, 21 Nov 2011 15:54:25 -0500=3D0AFrom:=3DA0 =3DA0 John Britt=
tpottery@GMAIL.COM>=3D0ASubject: Re: get the lead out=3D0A=3D0APaul,=3D0A=
=3D0AMy thou=3D
ghts are that you can't tell if lead glazes leach more than china =3D3D=3D0=
Apai=3D
nted=3D3D20=3D0Aglazes unless you test them. Even though you only put on sm=
all =3D
amounts - =3D3D=3D0Ayou=3D3D20=3D0Aare putting it directly on the surface, =
so if yo=3D
u are making functional w=3D3D=3D0Aork it is a=3D3D20=3D0Athin layer right =
where th=3D
e food is.=3D0A=3D0AJust my thoughts,=3D3D20=3D0A=3D0AJohn Britt=3D0A=3D0A*=
****=3D0A=3D0ATrue=3D
, but there is just almost no material there in the china=3D0Apaint.=3D0AIt=
's s=3D
o thin you can se through it.=3DA0 There just isn't as much lead to=3D0Alea=
ch a=3D
s there is with a lead glaze.=3DA0 And I always tell everyone, you=3D0Adon'=
t pu=3D
t it where it comes in contact with food.=3D0A=3D0A=3D0APaul Lewing=3D0Awww=
.paullew=3D
ingtile.com=3D0A=3D0APaul,=3D0A=3D0AI am with you on the" no contact with f=
ood surf=3D
aces". Then there is no=3D0Aworry for the consumer, only for the potter.=3D=
A0 B=3D
ut I will still argue=3D0Athat even though there is a small amount in china=
p=3D
aints, the fact=3D0Athat the veneer is on the surface makes it more vulnera=
bl=3D
e to=3D0Aleaching.=3D0A=3D0ATake care,=3D0A=3D0AJohn Britt=3D0Awww.paullewi=
ngart.com=3D0A
Wyndham Dennison on fri 25 nov 11
> Rimas
> This has to be one of the sanest, most rational,
> non-hysterical comments on the topic I've read
> or heard of in years.
> Thank you Rimas, thank you.
> Des
>
> On 25/11/2011 1:24 AM, Rimas VisGirda wrote:
>> I'm thinking the key-word here is leaching...
> --
> Des& Jan Howard
> Lue Pottery
> Lue NSW
> Australia
> 2850
I also agree But.....
It's the perception of lead in a glaze not the facts of how lead is
encapsulated into the glaze that has the general public (and some
potters) is a uproar. Customers still ask if pottery is safe to use,
because they have heard that potters glazed with lead 50 years ago, they
believe functional pottery is unsafe to use.
Every now and then there's a news report that something from China in a
Walmart was tested for lead and we get the fall out for months after.
To the general public, the word "LEAD" means poison and death.
So I agree that Lead can be safely used but the perception of the
dangers of Lead out weigh any reasons to use it.
Wyndham
John Britt on fri 25 nov 11
Rimas,
I don't want to get into an arguement about lead and lead release because=
=3D
I=3D20
think it is obvious. Just like smoking. I don't try to convince anyone a=
=3D
bout the=3D20
dangers of smoking because it is obvious.=3D20
But there are so many things I disagree with in your post I have to say=3D2=
0=3D
something.
You say: "I'm thinking the key-word here is leaching... When lead is in =
=3D
a stable=3D20
glaze matrix as in glaze or overglaze (which is actually a very, very, ve=
=3D
ry low=3D20
fire glaze) it won't leach unless attacked by a VERY strong acid, which w=
=3D
ould=3D20
tend to decompose (leach) any material it was brought in contact with. No=
=3D
w, if=3D20
lead is present in a stable glaze matrix, it won't leach out; the some 30=
=3D
year=3D20
old test being to put vinegar or lemon juice or orange juice in contact w=
=3D
ith the=3D20
suspect piece and see if there is "scumming" at the interface, indicating=
=3D
that=3D20
the (weak) acid is breaking down the glaze and releasing the constituents=
=3D
of=3D20
the glaze (which might include lead) as in underfired ware from Mexico wh=
=3D
ich=3D20
started the frenzy in the 70's to my recollection."
So the key words are "When lead is in a stable glaze matrix".. I would a=
=3D
dd the=3D20
significant work "IF". So the problem is ensuring this is the case. Ther=
=3D
e are=3D20
countless cases where this did not occur. (I will cite the Duncan recall!=
=3D
)
You say: " If I'm not mistaken we eat off of lead glazed items all the ti=
=3D
me, such=3D20
as restaurant ware..."
I don't think that this is correct. I know Homer Laughlin is lead-free an=
=3D
d Hall=3D20
China ( which are large suppliers to restaurants).=3D20=3D20
http://www.hlchina.com/
Says lead free on that opening page. I think they have lead free stamped =
=3D
on=3D20
the bottom of the piece too? I am sure some have lead in them but they ha=
=3D
ve=3D20=3D20
very strict standards for lead release which is getting tighter and tight=
=3D
er every=3D20
year. (Which goes to the seriousness of lead and lead release.) Stay away=
=3D
from=3D20
it !
You say " The user however should have no fear of lead bearing glazes IF =
=3D
THEY=3D20
ARE LOCKED INTO A STABLE GLAZE MATRIX, the only problem comes if the=3D20
glaze is underfired..."
The only problem is a major problem. That is why it is to be avoided beca=
=3D
use it=3D20
is almost impossible to ensure that every items is fired correctly!
You say: "But my hypothesis is, that amount of lead ingested by slicing=
=3D
ones=3D20
steak is so insignificant
statistically that
it makes the whole discussion moot..."
This is reducing the serious problem to its most simplistic form! All the=
=3D
cases of=3D20
lead poising and all you can come up with is slicing your steak? Come on=
=3D
. With=3D20
all the pitchers of orange juice, plates of tomato sauce, wine, sauerkrau=
=3D
t, etc.=3D20
We eat lots of very acidic foods and there is no need for lead.
Sorry to disagree on Thanksgiving.
Best, I'm out,
John Britt Pottery=3D20=3D20
John Britt on fri 25 nov 11
Come to think of it....if when everyone went out to eat, they asked the =
=3D
restaurant manager if their dinnerware was lead-free.......it might reviv=
=3D
e the=3D20
American Pottery industry. Go Homer Laughlin!!!
John Britt
Edouard Bastarache on fri 25 nov 11
Dennison,
too many journalists on this planet,,,
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://edouardbastaracheblogs2.blogspot.com/
http://www.facebook.com/edouard.bastarache
----- Original Message -----
From: "Wyndham Dennison"
To:
Sent: Friday, November 25, 2011 10:19 AM
Subject: Re: lead out
>> Rimas
>> This has to be one of the sanest, most rational,
>> non-hysterical comments on the topic I've read
>> or heard of in years.
>> Thank you Rimas, thank you.
>> Des
>>
>> On 25/11/2011 1:24 AM, Rimas VisGirda wrote:
>>> I'm thinking the key-word here is leaching...
>> --
>> Des& Jan Howard
>> Lue Pottery
>> Lue NSW
>> Australia
>> 2850
>
> I also agree But.....
> It's the perception of lead in a glaze not the facts of how lead is
> encapsulated into the glaze that has the general public (and some
> potters) is a uproar. Customers still ask if pottery is safe to use,
> because they have heard that potters glazed with lead 50 years ago, they
> believe functional pottery is unsafe to use.
> Every now and then there's a news report that something from China in a
> Walmart was tested for lead and we get the fall out for months after.
> To the general public, the word "LEAD" means poison and death.
> So I agree that Lead can be safely used but the perception of the
> dangers of Lead out weigh any reasons to use it.
> Wyndham
>
Des & Jan Howard on fri 25 nov 11
Rimas
This has to be one of the sanest, most rational,
non-hysterical comments on the topic I've read
or heard of in years.
Thank you Rimas, thank you.
Des
On 25/11/2011 1:24 AM, Rimas VisGirda wrote:
> I'm thinking the key-word here is leaching...
--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850
02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624
Rimas VisGirda on sat 26 nov 11
Yes, presence of lead can be injurious and unhealthy in a glaze. I see your=
point(s). -Rimas
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