John Rodgers on mon 26 jul 04
I need to add aomething to a Floating Red glaze to stop it from running
all over. I'm sure alumina is what is needed, but alumina what????
Hydrate or Oxide? I don't have either on hand, must buy it, and
definitely want to get the right stuff the first time.
Anyone know which works? Or maybe something else might be better??
TIA!
Regards,
John Rodgers
Jim V Brooks on mon 26 jul 04
John - try adding some EPK or OM4 clay. I often have to add three to 8
percent to control the flow. Jim in Denton
Scott Paulding on mon 26 jul 04
grolleg works too. in fact, you can just up the amount of whatever the clay is
in the recipe (assuming there is one), and that should work.
from what I've heard, alumina can be absorbed through the skin, so handling raw
alumina hydrate or oxide may be risky.
-scott
--- Jim V Brooks wrote:
> John - try adding some EPK or OM4 clay. I often have to add three to 8
> percent to control the flow. Jim in Denton
>
>
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Ivor and Olive Lewis on tue 27 jul 04
Dear John Rodgers,
A proposition which raises some interesting questions about current
Theory of Glaze Design and Construction.
I suppose one knee jerk reaction is to say "Yes, either of these
materials will work, Or why not just use Kaolin.". If asked why, I
would tell you Alumina in some form or other must work because Frank
Hamer told me Al2O3 is the strongest promoter of viscosity is when I
read my copy of his book. Why Kaolin? Well this is rich in Alumina,
not as Aluminium Oxide but as part of a very refractory material which
dissolves with difficulty in a silicate melt unless the temperature is
very, very high. But I would be hard pressed to give you a
"Scientific" reason for the use of either material.
It will be interesting to read what other people have to say on this
one.
Since I do not know your recipe it might not be a wise move to suggest
removing a percentage of your melting agents,which contain K+, Li+,
Na+, B+++, which are known to increase fluidity. However, omission of
a proportion of some of these compounds might be a better option. But
it is feasible to do this.
Best Regards,
Ivor Lewis.
Redhill,
S. Australia.
----- Original Message -----
From: "John Rodgers"
To:
Sent: Tuesday, 27 July 2004 5:58
Subject: Alumina Hydrate or Oxide
> I need to add aomething to a Floating Red glaze to stop it from
running
> all over. I'm sure alumina is what is needed, but alumina what????
> Hydrate or Oxide? I don't have either on hand, must buy it, and
> definitely want to get the right stuff the first time.
>
> Anyone know which works? Or maybe something else might be better??
>
> TIA!
>
> Regards,
>
> John Rodgers
>
>
______________________________________________________________________
________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your
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> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Ivor and Olive Lewis on tue 27 jul 04
Dear Friends,
Another thought on this one.
Is there any correlation in terms of increase in Cone increments for
each percentage point of Kaolin added to a glaze formulation?
For example, might you need to increase your maturity cone by a value
of one for each percentage of Kaolin added. So, add 4 % and go up from
cone 6 to cone 10 to ensure maturity.
Or would it be prudent to allow more time and slowly back off the
ramp-up as you watch the first witness cone bend? Let the kiln run for
another two hours to ensure the extra chemicals dissolve in the melt,
which they would have to do to change the viscosity.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Snail Scott on tue 27 jul 04
At 03:28 PM 7/26/04 -0500, you wrote:
>...I'm sure alumina is what is needed, but alumina what????
>Hydrate or Oxide?
They'll both do the same thing. Alumina hydrate
is less concentrated than alumina oxide (it
contains more molecules that aren't alumina, so
less alumina per unit weight), but this is
generally reflected in the cost anyway, so try
either.
-Snail Scott
Ron Roy on tue 27 jul 04
Hi John,
Send me the recipe and I'll work out a line blend adding alumina till the
running stops - keeping the ratio the same.
You can use alumina hydrate but it affects the melting more then Kaolin.
Just tell me what material you want to use - alumina - hydared or calcined
or what kaolin.
RR
>I need to add aomething to a Floating Red glaze to stop it from running
>all over. I'm sure alumina is what is needed, but alumina what????
>Hydrate or Oxide? I don't have either on hand, must buy it, and
>definitely want to get the right stuff the first time.
>
>Anyone know which works? Or maybe something else might be better??
>
>TIA!
>
>Regards,
>
>John Rodgers
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Edouard Bastarache Inc. on tue 27 jul 04
Scott,
alumina does not penetrate the skin.
Later,
"Ils sont fous ces quebecois"
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
http://www.digitalfire.com/education/toxicity/
Scott Paulding on tue 27 jul 04
As I said, "from what I've heard." Nobody has actually shown it to me written
down anywhere, but I've heard it from three people who all learned glaze calc
from different places. One mentioned it to me when I was forming balls of kiln
wadding w/ my bare hands (50/50 Alumina Hydrate and EPK), and another was
wearing rubber gloves while working with kiln wadding (the same recipe, I
think), again because she said it can absorb through the skin.
Thanks all for the clarification.
-scott
--- "Edouard Bastarache Inc." wrote:
> Scott,
>
>
> alumina does not penetrate the skin.
>
>
> Later,
>
>
> "Ils sont fous ces quebecois"
> 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
> http://www.digitalfire.com/education/toxicity/
>
>
______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
=====
"I should have been a plumber."
-Albert Einstein
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Ivor and Olive Lewis on tue 27 jul 04
Dear Scott Paulding,
You say <<..from what I've heard, alumina can be absorbed through the
skin, so handling raw alumina hydrate or oxide may be risky... >>
From Whom, Where and When? Then How? and Why risky?
Just inquisitive.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
mailtoandrew@FSMAIL.NET on wed 28 jul 04
Hello John,
When alumina is mentioned as a ceramic raw material this most frequently
refers to calcined alumina, Al2O3, produced from bauxite. Mineralogically
most commercial grades are greater than 98% alpha alumina.
For your application my choice between kaolin or alumina would be the
latter. Reasons ... it is more refractory and will have lower levels of
Fe2O3 and TiO2. However if it is a choice between using kaolin already in
stock and a special order of alumina Id go for the clay.
Scotts mention of a health issue was surprise as Id never heard anything
before despite using it for years. Ive checked a few MSDS and found no
cause for alarm other than it being a nuisance dust and being a potential
skin irritant; it is after all a very good abrasive.
Regards,
Andrew
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