Edouard Bastarache on thu 4 apr 02
Hello Paul,
according to A.E.Dodd in Dictionary of Ceramics,
lead silicate comprises a group of lead frits.
"It is a material obtained by fritting lead oxide with
silica in various ratios.
The usual ratio is PbO.2SiO2 and a frit of this
composition is known as "lead bisilicate".
so-called lead monosilicate is approx. PbO.0.75SiO2.
Tribasic lead silicate, 3PbO.SiO2 finds some use in
making lead glasses.
The bilisicate is used in pottery glazes, enamels, etc."
Sorry, I have not found yet any information concerning
the hazardous decomposition products for "lead bisilicate"
in the documentation I have at hand except one MSDS
supplied by our friends at Potterycrafts in the UK.
It is stated there is no hazardous decomposition
products, I found this file on Google.com.
According to Sax's Dangerous Properties of Industrial
Materials, lead silicate PbO.SiO2 does emit toxic fumes
of Pb when heated to decomposition (melting point 766=B0).
So, being a frit, I do not think "lead bisilicate" does behave
like the 3 non-complex lead compounds discussed below,
temperature-wise. I will search some more my
documentation in coming days and let the list know
if I find something.
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
Later,
----- Original Message -----
From: Paul Lewing
To:
Sent: Wednesday, April 03, 2002 11:33 PM
Subject: Re: : lead dangers
> on 4/3/02 3:17 PM, Edouard Bastarache at edouardb@SOREL-TRACY.QC.CA wro=
te:
>
> > 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 hea=
ted
to
> > decomposition (over 500 C), there is release of oxygen and emission o=
f
toxic
> > fumes of lead.
> >
> > Yellow lead ((Pb) is unstable under the following conditions: if heat=
ed
at
> > 300-400 C
> > it transforms into lead tetraoxide.
>
> Edouard, does lead bisilicate also decompose? If so, under what
conditions
> and with what byproducts?
> Paul Lewing, Seattle
>
>
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