Paul Lewing on thu 12 jan 06
I was researching some stuff last night, and looking up the melting points
of various fluxes. I found this: (temps are all C)
lead 327
bismuth 271
lithium 180
sodium 97
potassium 63
boron 2076
What? The melting point of boron is 2076 C? Why is it such an active melter
then?
Paul Lewing
Bruce Lucas on thu 12 jan 06
Paul Lewing wrote:
>What? The melting point of boron is 2076 C?
>
>
That's the melting point of elemental boron
(http://en.wikipedia.org/wiki/Boron). The flux used in glass is as I
understand it boron trioxide (http://en.wikipedia.org/wiki/Boron_oxide),
which has a much lower melting point.
Bruce Lucas
Steve Slatin on thu 12 jan 06
Paul --
We generally use Boron oxide, B2O3 in our glazes. It
melts at 450 C or thereabouts. I vaguely recollect that
pure crystalline boron has a characteristic reaction
with free oxygen or nitrogen at a fairly low temperature
to form BN or B2O3.
John H did some testing last year that seemed to show
that B's principal function was to lower the melting temp
of the glaze overall; I can't remember my how much
he reported the melting temperature changed, but I
remember it as a striking number.
-- Steve Slatin
Paul Lewing wrote:
I was researching some stuff last night, and looking up the melting points
of various fluxes. I found this: (temps are all C)
lead 327
bismuth 271
lithium 180
sodium 97
potassium 63
boron 2076
What? The melting point of boron is 2076 C? Why is it such an active melter
then?
Steve Slatin --
And I've seen it all, I've seen it all
Through the yellow windows of the evening train...
---------------------------------
Yahoo! Photos – Showcase holiday pictures in hardcover
Photo Books. You design it and we’ll bind it!
Taylor, in Rockport TX on fri 13 jan 06
Hey Paul and Ivor and y'all:
I think what Ivor is trying to say in his own sweet way is don't ask why
boron has such a high melting point but rather why boron oxides have such a
lower melting point. And why oh why can't we find a great Gerstley Borate
substitute under the ground? That Ivor is such a stinker.
Compounds of boron:
boron (III) oxide
* Formula as commonly written: B2O3
* Hill system formula: B2O3
* CAS registry number: [1303-86-2]
* Formula weight: 69.62
* Class: oxide
Synonyms
* boron (III) oxide
* boron oxide
* boron trioxide
* diboron trioxide
Physical properties
* Colour: white
* Appearance: crystalline solid
* Melting point: 450=B0C <----Ivor, you're a stinker.
* Boiling point: 2065
* Density: 2550 kg m-3
On Fri, 13 Jan 2006 19:33:49 -0800, Paul Lewing
wrote:
...I don't understand what you mean by that last comment, Ivor. When did I
>ever buy lithium, sodium, or potassium at my ceramic supplier's either?
>They're all oxides, just like the boron, in the forms we buy them in.
Eleanora Eden on fri 13 jan 06
According to Digitalfire:
-Boric oxide has no melting point, but a=20
progressive softening and melting range from=20
300-700C
Eleanora
>Paul --
>
> We generally use Boron oxide, B2O3 in our glazes. It
> melts at 450 C or thereabouts. I vaguely recollect that
> pure crystalline boron has a characteristic reaction
> with free oxygen or nitrogen at a fairly low temperature
> to form BN or B2O3.
>
> John H did some testing last year that seemed to show
> that B's principal function was to lower the melting temp
> of the glaze overall; I can't remember my how much
> he reported the melting temperature changed, but I
> remember it as a striking number.
>
> -- Steve Slatin
>
>
>
>
>Paul Lewing wrote:
> I was researching some stuff last night, and looking up the melting poin=
ts
>of various fluxes. I found this: (temps are all C)
>
>lead 327
>bismuth 271
>lithium 180
>sodium 97
>potassium 63
>boron 2076
>
>What? The melting point of boron is 2076 C? Why is it such an active melter
>then?
>
>Steve Slatin --
>
>And I've seen it all, I've seen it all
>Through the yellow windows of the evening train...
>
>---------------------------------
>Yahoo! Photos =96 Showcase holiday pictures in hardcover
> Photo Books. You design it and we=92ll bind it!
>
>___________________________________________________________________________=
___
>Send postings to clayart@lsv.ceramics.org
>
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>
>Moderator of the list is Mel Jacobson who may be=20
>reached at melpots@pclink.com.
John Hesselberth on fri 13 jan 06
On Jan 12, 2006, at 8:27 PM, Paul Lewing wrote:
> I was researching some stuff last night, and looking up the melting
> points
> of various fluxes. I found this: (temps are all C)
>
> lead 327
> bismuth 271
> lithium 180
> sodium 97
> potassium 63
> boron 2076
>
> What? The melting point of boron is 2076 C? Why is it such an
> active melter
> then?
> Paul Lewing
>
Hi Paul,
The numbers you are quoting are the metal melting points. Using the
appropriate oxide numbers would be more relevant. But it is also
probably true that "fluxing or melting" power is some complex
combination of actual melting of the various materials and
solutioning. So I could speculate that some of the materials we call
fluxes may simply dissolve readily in whatever is already melted and
then contribute to making the resulting melt/solution a stronger
solvent for the more "stubborn" oxides.
Regards,
John
Paul Lewing on fri 13 jan 06
on 1/13/06 4:56 PM, Ivor and Olive Lewis at iandol@WESTNET.COM.AU wrote:
> Come off it Paul. When did you ever buy "Boron" from a ceramic supply =
> house.
>
> Compounds of "Boron" are the Scavengers of the Metallurgical Trades. =
> Compounds of "Boron" are the Cone 6 firer's best friend. Where would =
> they be without a good old boron frit ?
>
> Some how or other you have got your questions mixed up.
I don't understand what you mean by that last comment, Ivor. When did I
ever buy lithium, sodium, or potassium at my ceramic supplier's either?
They're all oxides, just like the boron, in the forms we buy them in.
Paul Lewing, Seattle
Steve Slatin on sat 14 jan 06
Taylor --
Why the lower melting point? It's probably easiest to say 'it just is.'
Why no great GB substitute under ground? That one's easier --
Borates are mostly rather soluble IN WATER. Most of what's
under ground at readily available, economically recoverable depths
is non-soluble. Hence borates are found mostly in desert locations;
ones that have been deserts for (geologically) long times.
As for mineral deposit formation; high heat/pressure is usually
involved. Since borates melt at low temps, they don't precipitate
to mineral deposits in large quantities low down giving the massive
deposits that we sometimes find for other things that then become
economically recoverable ... and higher up towards the surface,
the probability of water intrusion taking the stuff away is higher,
etc. etc.
That's my story, and I'm sticking to it ...
-- Steve Slatin
"Taylor, in Rockport TX" wrote:
Hey Paul and Ivor and y'all:
I think what Ivor is trying to say in his own sweet way is don't ask why
boron has such a high melting point but rather why boron oxides have such a
lower melting point. And why oh why can't we find a great Gerstley Borate
substitute under the ground?
Steve Slatin --
And I've seen it all, I've seen it all
Through the yellow windows of the evening train...
---------------------------------
Yahoo! Photos – Showcase holiday pictures in hardcover
Photo Books. You design it and we’ll bind it!
Ivor and Olive Lewis on sat 14 jan 06
Paul Lewing asked ....
<points
of various fluxes. I found this: (temps are all C)
lead 327
bismuth 271
lithium 180
sodium 97
potassium 63
boron 2076
What? The melting point of boron is 2076 C? Why is it such an active =
melter
then? >>
Come off it Paul. When did you ever buy "Boron" from a ceramic supply =
house.
Compounds of "Boron" are the Scavengers of the Metallurgical Trades. =
Compounds of "Boron" are the Cone 6 firer's best friend. Where would =
they be without a good old boron frit ?
Some how or other you have got your questions mixed up.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
"Boron", by the way, boils at 3700 deg C ; "Lead" at 1760 deg C ; =
"Potassium" at 777 deg C ; "Sodium" at 900 deg C ; "Lithium" at 1360 deg =
C ; "Bismuth" at 1650 deg C . And our old friend "Calcium" melts at 840 =
deg C then boils at 1490 deg C
Ivor and Olive Lewis on sat 14 jan 06
Dear John Hesselberth,
Thank you for supporting the viewpoint that I have steadfastly kept in =
my relevant replies to Clayart over the past six years.
Compounds that decompose to give highly refractory oxides, in the main =
Carbonates of Metals from Group 2 of the Periodic Table and Zinc Oxide, =
make their contribution by altering the physical characteristics of a =
developing liquid derived from Frits, Borates and The Felspar Group when =
they have dissolved in the melt.
John Hesselberth wrote << So I could speculate that some of the =
materials we call
fluxes may simply dissolve readily in whatever is already melted and
then contribute to making the resulting melt/solution a stronger
solvent for the more "stubborn" oxides.>>
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on sun 15 jan 06
Dear Paul Lewing
You ask <When did I
ever buy lithium, sodium, or potassium at my ceramic supplier's either?
They're all oxides, just like the boron, in the forms we buy them in.
Paul Lewing, Seattle..>>
If you were already aware of this, why draw attention to the properties =
of the Elements? Remember this from your original post? <melting point of boron is 2076 C? Why is it such an active melter then? =
>>
I was not aware that oxides of Potassium, Sodium or Lithium were =
available from ceramic suppliers (though they may be in American =
catalogues). Carbonates of these elements certainly are, as are mineral =
compounds and Frits that contain them. Nor is Boron Oxide, though Boric =
Acid is, as is Sodium Borate and again, some frits. All have relatively =
low melting points and a subtle ability to dissolve metallic oxides and =
sequester metallic ions. Perhaps that is what I should have told you.
My comment <> =
Possibly I should have substituted "Concepts" for "Questions". If I =
caused you concern I apologise.
Best regards,
Ivor
Ivor and Olive Lewis on mon 16 jan 06
Dear Taylor, in Rockport TX,=20
Thanks for your support. Boron Chemistry is almost as complex as that of =
Carbon and its compounds and as interesting as Silica and its compounds. =
For those who understand, it may be that the configuration of the =
Valency Electrons of the elemental atoms do not match atom Valency =
Orbitals that makes for compounds that have interesting characteristics.
I am sure there are pockets of Gerstly Borate tucked away in the Mojave =
Desert that could be exploited by enterprising youngsters equipped with =
picks and shovels. After all, mineral borates cover an area 6 km by 1.5 =
km or thereabouts and the beds are upwards of fifty metres thick.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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