Earl Brunner on tue 16 feb 99
Paul Lewing posted a version of the following recipe on the list last
summer (this current form is the result of a triaxle blend) (Cone 5-6)
Lithium carbonate 9.50
Bone ash 9.50
Nepheline syenite 55.66
EPK 15.84
Red iron oxide 2.35
Rutile 7.15
--------
100.00
The problem is that I have never been able to reproduce the results of
the triaxle.
When I attempted to look at the formula using software, non of the limit
formulas
included Lithium.
Still, with the RO at unity it appears high in alumina and low in silica
Al203 at .57 and Si02 at 2.0
I left the alumina alone, but increased the silica by adding 13.5 Flint
to increase to 2.5, that of course lowered the percentage of each of the
rest of the ingredients a little.
CaO .29 Al2O3 .53 SiO2 2.5
Li2O .36 P2O5 .09
K2O .08 TiO2 .25
Na2O .27 Fe2O3 .04
I want to matt this glaze down some like the original test, It currently
is running off
test tiles. I guess my question is, am I going in the right direction?
With all that alumina, why is it running? And how DO you factor in
lithium? Or Strontium for that matter?
Earl Brunner
Las Vegas, NV
Paul Lewing on wed 17 feb 99
Hi, Earl,
I don't have time to run your new recipe through the software, but
here's a limit formula for lithiom. The only book I've ever seen that
had limits for lithium, lead, or strontium is Richard Zakin's
"Mastering the Craft". He lists them as, for cone 3-7, LiO .05- .2;
PbO .2- .5; SrO 0-.4. For cone 8-10, LiO 0- .2; SrO 0-.7. Lead
is gone at cone 10. so no limit formulas.
I hope this helps.
Paul Lewing, Seattle
David Hewitt on thu 18 feb 99
Earl,
For what it is worth I use the following guide line limit formula for
cone 6 of up to .2 lithium and up to .4 strontium. On this basis your
lithium is high. It is certainly a strong flux. If you wish to make this
more matt, why not consider replacing the lithium with magnesium
carbonate and do a line blend. That is between the original recipe and
one with no lithium carbonate and 9.5% magnesium carbonate. The
coefficient of expansion will be improved in the process. Replacing all
the lithium with magnesium gives me the following analysis:-
K2O 0.09 Al2O3 0.58 SiO2 2.14
Na2O 0.28 Fe2O3 0.05 TiO2 0.28
CaO 0.29 P2O5 0.10
MgO 0.35
On the figures that I use for expansion this reduces the coefficient
from 7.20 to 7.06
David
In message , Earl Brunner writes
>----------------------------Original message----------------------------
>Paul Lewing posted a version of the following recipe on the list last
>summer (this current form is the result of a triaxle blend) (Cone 5-6)
>Lithium carbonate 9.50
> Bone ash 9.50
> Nepheline syenite 55.66
> EPK 15.84
> Red iron oxide 2.35
> Rutile 7.15
> --------
> 100.00
>The problem is that I have never been able to reproduce the results of
>the triaxle.
>When I attempted to look at the formula using software, non of the limit
>formulas
>included Lithium.
>Still, with the RO at unity it appears high in alumina and low in silica
>
>Al203 at .57 and Si02 at 2.0
>I left the alumina alone, but increased the silica by adding 13.5 Flint
>to increase to 2.5, that of course lowered the percentage of each of the
>rest of the ingredients a little.
>CaO .29 Al2O3 .53 SiO2 2.5
>Li2O .36 P2O5 .09
>K2O .08 TiO2 .25
>Na2O .27 Fe2O3 .04
>
>I want to matt this glaze down some like the original test, It currently
>is running off
>test tiles. I guess my question is, am I going in the right direction?
>With all that alumina, why is it running? And how DO you factor in
>lithium? Or Strontium for that matter?
>Earl Brunner
>Las Vegas, NV
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
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