Jiri Minarik on thu 30 dec 99
Last week,while waiting for my clay to be loaded ,I perused a book titled
"Slipware".It is a beautiful book ,surveying some of the leading contemporary
artists working in low fire. The artists covered, come from Canada,USA,UK,
France,Hungary and Netherlands, and every single one of them (with one
exception) uses lead based glazes.It seems that there really is no substitute
for lead if you want softness,color responsivness and glaze fit. Of course I
use lead free glazes but think with nostalgia about some lead glazes that I
had used eons ago before I abandoned them out of concern for my own health
and due to customers' questions about lead content.
Jiri in Berkeley
Paul Lewing on fri 31 dec 99
Jiri, You're really right about lead glazes. I've played with some and
use one particular one on occasion because it makes a color I have just
not been able to come up with any other way.
Yeah, lead makes incredible colors; it's cheap; it's widely available in
most parts of the world; it makes glazes with very long firing ranges,
so you don't have to have a very sophisticated kiln; it makes glazes
that almost seem to be elastic, they have such a wide range of bodies
they will fit.
It just has this ONE SMALL disadvantage....
Paul Lewing, Seattle
Bob Wicks on fri 31 dec 99
Jim:
I'm certainly not the last word authority on lead, but have you tried Lithium
as a substitute? It is adjacent to lead on the periodic table. I agree that
lead is too hazardous to use in our glazes. Checking the periodic table
should give you some new insights. Happy New Year. Enjoy SAFE pottery.
Bob
Bruce Girrell on tue 4 jan 00
Bob Wicks wrote:
>I'm certainly not the last word authority on lead, but have you tried
Lithium
>as a substitute? It is adjacent to lead on the periodic table. I agree
that
>lead is too hazardous to use in our glazes. Checking the periodic table
>should give you some new insights.
Do you mean maybe bismuth? Lithium and lead are very far apart. Looking at
the periodic chart, I would guess that the element most likely to act like
lead would be tin, as it is in the same column as lead and will take on the
same valences. However, I don't know how lead accomplishes its magic in
glazes, so maybe its valences don't matter and maybe the atomic size does
(in which case bismuth would be the next closest). Glaze gurus? What does
lead actually _do_ (chemically) in glazes that traditionally made it so
useful?
Bruce "now you've got _me_ wondering"
Alex Wilson on wed 5 jan 00
<< In a message dated 01/04/2000 7:48:41 AM Central Standard Time,
bigirrell@microlinetc.com writes:
<< Do you mean maybe bismuth? >>
Hello Bruce, I heard a while back that the potteries in India were using
Bismuth Oxide as a replacement for Lead Oxide. Perhaps they have a cheap
source of the stuff; last I checked, it was about the price of gold (also not
far away, valence-wise) here in the 'States. I think I recall its mention in
Parmelee.
But if it were such a good substitute - why are we all, including industrial
operations, using calcium boro-silicate fritts? Aside from the exhorbitant
cost, I mean.
BFN,
Alex, "Can I have my lead back,please, mister?", The Scottish Potter >>
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