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subject: calcining alumina

updated thu 17 jul 03

 

iandol on tue 15 jul 03


Dear Friends,
Perhaps before we discuss "Calcined Alumina" we ought to define =
"Alumina" and "Calcine".
Robert Fournier tell us that Calcining is used to remove Water of =
Hydration.
If you are dealing with Pure Alumina there is no water present. If you =
have bought Aluminium Hydrate then Calcination will eliminate the =
Hydroxyl radicles from the composition.=20
In the Sintering Lab we used Alumina as an adsorbent of residual Oxygen =
in the Hydrogen used for our kiln atmosphere. I was told Pure Alumina =
had a catalytic action which, even at room temperature, was able to =
sponsor the chemical reaction between Hydrogen and Oxygen. We renewed =
the catalytic action when the tanks became saturated with water by =
blasting hot air through them.
Perhaps someone believes that pure aluminium oxide adsorbs sufficient =
water to upset the weighing of a glaze batch.
Best regards,
Ivor Lewis. Redhill, South Australia.

Ababi on wed 16 jul 03


My privet (national) adviser said that the alumina hydrate makes kind of
"bubbles when the hydrogen flies away. Therefore "that matte glaze" I
choose to add to the alumina hydrate will have softer matte.
In the new crystal glazes book they said to use on the pedestals of the
wares a kiln wash based on alumina oxide. I did not have on hand so I
calcined and used. Because I needed more I used the Hydrate and it was
fine at^6 ox.

I paid about 200$ for small business office yet when I start to write in
English it jumps to Hebrew and the other way around!
What is the matter with you Bill?




Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm







Ababi Sharon

Glaze addict

Kibbutz Shoval Israel

ababisha@shoval.org.il

http://members4.clubphoto.com/ababi306910

http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm


-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of iandol
Sent: Tuesday, July 15, 2003 8:25 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Subject: calcining alumina

Dear Friends,
Perhaps before we discuss "Calcined Alumina" we ought to define
"Alumina" and "Calcine".
Robert Fournier tell us that Calcining is used to remove Water of
Hydration.
If you are dealing with Pure Alumina there is no water present. If you
have bought Aluminium Hydrate then Calcination will eliminate the
Hydroxyl radicles from the composition.
In the Sintering Lab we used Alumina as an adsorbent of residual Oxygen
in the Hydrogen used for our kiln atmosphere. I was told Pure Alumina
had a catalytic action which, even at room temperature, was able to
sponsor the chemical reaction between Hydrogen and Oxygen. We renewed
the catalytic action when the tanks became saturated with water by
blasting hot air through them.
Perhaps someone believes that pure aluminium oxide adsorbs sufficient
water to upset the weighing of a glaze batch.
Best regards,
Ivor Lewis. Redhill, South Australia.

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