piedpotterhamelin@COMCAST.NET on sat 10 oct 09
Hi=3D20
I received and responded off ClayArt to Mr Hansen's email which he posted o=
=3D
n Clayart; so I=3DC2=3DA0now must publicly respond to all with my reply, al=
thou=3D
gh I haven't heard back from him. See below.=3D20
I was intrigued to learn from a ClayArter=3DC2=3DA0that commercial lead bea=
ring=3D
glaze (the little jars) production was discontinued earlier this year. Fer=
=3D
ro=3DC2=3DA0is listing on their website that=3DC2=3DA0they=3DC2=3DA0supply =
frits and fl=3D
uxes containing lead.=3D20
To Mel and Lilly, I included a link to a scottish potter's site below. She =
=3D
formulates a honey pb glaze and several of her associates (side bar links o=
=3D
n her site) also use it. One (sorry, I only have the memory, not the link) =
=3D
potter stated the the beauty of the lead glaze outweighed all the=3DC2=3DA0=
risk=3D
s!=3D20
Greg Shooner of TurtleCreek Pottery and the Studios of David T. Smith curre=
=3D
lty reproduce redware pottery with a lead glazes (I don't know if they are =
=3D
raw lead or lead frit) and mark the pottery as "decorative and not safe for=
=3D
food". These wares sell for hundreds if not thousands of dollars.=3D20
My wife and I recently examined a circa 1970's industrial ware=3DC2=3DA0tea=
pot =3D
where not just the glaze disappeared from the interior, but the ceramic was=
=3D
pitted as well! That must be one strong tea! I note this as both the studi=
=3D
o potter and the industrial producer has the=3DC2=3DA0 responsibility and a=
vail=3D
able knowledge to produce safe wares. Ignorance is not a tolerable excuse.=
=3D
=3D20
I welcome commentary, insight and criticism of my posts; I would be the fir=
=3D
st to correct myself; your teaching me helps me to teach others.=3DC2=3DA0=
=3D20
Thank you=3D20
Rick=3D20
On Fri, 9 Oct 2009 11:59:16 +0000 (UTC), piedpotterhamelin@comcast.net=3D20
wrote:=3D20
> Hi=3D20
>=3D20
> I am not sure what you meant by "the association between the safe use of=
=3D
=3D20
> modern lead frit and the processes described in this post." What processe=
=3D
s=3D20
> are you referencing in my post?=3D20
>=3D20
> Of course fritted lead doesn't equal raw lead and I=3DC2=3DA0 did state t=
his =3D
in the=3D20
> article;=3D20
>=3D20
> " The=3DC2=3DA0 use of lead=3DC2=3DA0 continues today but under very cont=
rolled c=3D
onditions=3D20
>=3DC2=3DA0 and repeated fired ware testing that are not economically feasi=
ble =3D
for=3D20
> most studio potters." I should have qualified it as fritted lead.=3D20
Daniel Rhodes and Robin Hopper cautioned=3DC2=3DA0 in Clay and Glazes for t=
he=3D
=3D20
> Potter note on page 212;=3D20
"Another reason for using lead-frit is the poisonous nature of the=3D20
> oxide.When lead oxide is fritted with sufficient quantities of other oxid=
=3D
es, in most cases it is rendered nonpoisonous ."=3D20
>=3D20
> As you know, the ratios of lead to silica, alumina and calcium affect=3D2=
0
> solubility as well as this being controlled by temperature and ramp. Frit=
=3D
=3D20
> alone is different than the formulated and fired glaze.=3D20
>=3D20
>=3DC2=3DA0 Richard Zakin said that you could eat spoonfuls of lead frit wi=
thou=3D
t=3D20
> poisoning yourself.=3DC2=3DA0=3D20
=3DC2=3DA0If your issue in my email was with the concern that I have with s=
ome=3D
=3D20
> English, Mexican and Chinese wares, please understand that even on this=
=3D
=3D20
> ClayArt board, there were those who attempted to make functional=3D20
> reproduction redware pottery utilizing lead-frit and possessed not an iot=
=3D
a=3D20
> of formula knowledge. One woman simply wanted a honey glaze=3DC2=3DA0reci=
pe, =3D
she was angry and=3D20
> wanted a one size fits all solution.=3D20
>=3D20
> Rhodes and Hopper cited some parameters for a safe glaze here,=3D20
> http://books.google.com/books?id=3D3DwEOjXDfq5G8C&pg=3D3DPA212&lpg=3D3DPA=
212&dq=3D
=3D3Dfritted+lead+frit&source=3D3Dbl&ots=3D3DsSQwVaS2dP&sig=3D3Deu3XswlNcJW=
dvAoDDLH=3D
6f2EXK5M&hl=3D3Den&ei=3D3D0hjPSs3vIcXl8QbB07CABA&sa=3D3DX&oi=3D3Dbook_resul=
t&ct=3D3Dr=3D
esult&resnum=3D3D5&ved=3D3D0CBUQ6AEwBA#v=3D3Donepage&q=3D3Dlead%20frit&f=3D=
3Dfalse=3D20
>=3DC2=3DA0=3DC2=3DA0=3D20
>=3D20
> This potter noted that she questioned the use of=3DC2=3DA0 chrome=3DC2=3D=
A0 affec=3D
ting=3D20
> solubility; "was really good today and spent the morning mixing up a new=
=3D
=3D20
> batch of my honey glaze, and that's now soaking before I begin to sieve i=
=3D
t.=3D20
> Then I mixed up some trials of new slip colours, it's been on my list of=
=3D
=3D20
> things to do for an age. It'll be interesting to see how they look. Does=
=3D
=3D20
> Chrome react badly under a lead glaze anyone? ( What I mean is will it ma=
=3D
ke=3D20
> it unsafe?)" http://hannahmcandrew.blogspot.com/search?q=3D3Dhoney+glaze =
.=3D
=3D20
>=3D20
> Another redware potter that I personally know acknowledged to me that=3D2=
0
> his glaze was a crappy homemade fritted glaze mixed with a quantity of=3D=
20
> jug commercial glaze poured in. While my point is that there are lazy=3D2=
0
> potters who just don't care to do the work and take blind chances the poi=
=3D
nt=3D20
> I tried to make in my article was;=3D20
>=3D20
> Lead bearing glazes=3DC2=3DA0 can be safe, must be formulated correctly a=
nd t=3D
ested=3D20
> frequently and the latter generally is an inconvenience and expense too=
=3D
=3D20
> high for most studio potters.=3D20
> Historical ceramics utilized fritted lead to protect the factory workers.=
=3D
=3D20
> My readings of the last 33years have given me the understanding that this=
=3D
=3D20
> first occured in the c1770=3DC2=3DA0 English cream and pearlware factorie=
s . =3D
Later,=3D20
> in the 1830's, even American trade journals wrote of lead-free=3D20
> glaze recipes and the use of cuttle glass becomes obvious, although leach=
=3D
=3D20
> testing isn't referred to by any of the American=3D20
> factories. Leach testing for the consumer is discussed in the 1880's with=
=3D
=3D20
> toxicity=3DC2=3DA0 amounts being reduced by the 1980's as noted.=3DC2=3DA=
0=3D20
> What else can I tell you?=3D20
>=3D20
> About Your comment "No footnotes, no citations, merely assertions"=3D20
>=3D20
>=3DC2=3DA0=3DC2=3DA0 I am happy to cite any information that I shared but =
none wer=3D
e given=3D20
> as I simply wanted to be part of an informal discussion. I hope that I=3D=
20
> replied to your satisfaction and welcome your discussion and inquiries.=
=3D
=3D20
> Please instruct me i f you find that I am incorrect in my understanding o=
=3D
r=3D20
> confusing in my statements.=3D20
>=3D20
> Sincerely,=3D20
>=3D20
> Rick Hamelin=3D20
| |
|
