mo cain on sun 19 mar 00
------------------
A little knowledge is a dangerous thing and I certainly have little =
knowledge re
original glaze construction. Perhaps the Glaze Gurus can help. RR was of =
great
help a couple of years ago about my confusion about boric oxide and its =
place as
a flux or glass.
The following two recipes and their formulae are confusing me.
T1-12
Frit 3134 19.50 CaO 0.53=2A
MgO 0.28=2A
N eph Syenite 19.50 K2O 0.03=2A
Whiting 13.00 Na2O 0.17=2A
Talc 13.00 Al2O3 0.34 =
15.16=25
Epk 24.17 TiO2 0.00
Flint 10.83 B2O3 0.16
P2O5 0.00
Total 100.00 SiO2 2.14 =
56.04=25
Fe2O3 0.00
Si:Al 6.27 Expansion 7.28
SP2M
Frit 3134 24.00 18.32=25 CaO =
0.49=2A
=
Li2O
0.13=2A
Spodumene 24.00 18.32=25 MgO 0.29=2A
Barnard clay 8.00 6.11=25 K2O =
0.01=2A
Goldart 8.00 6.11=25 Na2O =
0.09=2A
Dolomite 26.00 19.85=25 TiO2 0.01
Zircopax 10.00 7.63=25 ZrO2 =
0.11
EPK 16.00 12.21=25 Al2O3 =
0.30
13.29=25
Flint 15.00 11.45=25 B2O3 =
0.16
=
P2O5
0.00
=
SiO2
2.03 52.23=25
Totals 131.00 100.00 Fe2O3 0.04
Si:Al 6.67 Expansion 6.22.
The first ( t1-12) fires very well at cone 4 with a nice smooth matte finish=
.
This glaze was developed using Ian Currie's suggested methodology. The =
second
glaze (SP2M) is a modified Zakin glaze and at Cone 4 runs completely off the=
pot
and sticks to the shelf.
Both appear to be within suggested limits for cone 4 and the amount of =
Al2O3 is
almost identical in both formulae. I used my trusty Insight program and the
glazes were fired side by side on the shelf with witness cones
Simply put why does the one run and the other not?
Your guidance and advice will be eagerly awaited and appreciated
Thanx MoCain .
Ron Roy on mon 20 mar 00
Hi Mo,
They are very similar - either you left out some thing - maybe the EPK??? -
better try it again.
the other explanation could be the kind of Spod you use. I am using one
that is available now - from Tanko which is very close to the Ausi Spod
avail in the US.
There was a version from Foote that melted much lower than this current
variety - it's much darker in the powdered form and fires quite glassy and
brown. If that is what you used I would not be surprised by the extra
melting - just melt some on a tile - of it's brown glass (lots of iron)
them get some of the currently available spod.
Perhaps Craig Martel will send you an analysis for the impure foote stuff -
I'm packing for NCECA now and I'm running short of time.
RR
>----------------------------Original message----------------------------
>------------------
>A little knowledge is a dangerous thing and I certainly have little
>knowledge re
>original glaze construction. Perhaps the Glaze Gurus can help. RR was of great
>help a couple of years ago about my confusion about boric oxide and its
>place as
>a flux or glass.
>
>The following two recipes and their formulae are confusing me.
>
>T1-12
>
>Frit 3134 19.50 CaO 0.53*
> MgO 0.28*
>N eph Syenite 19.50 K2O 0.03*
>Whiting 13.00 Na2O 0.17*
>Talc 13.00 Al2O3 0.34 15.16%
>Epk 24.17 TiO2 0.00
>Flint 10.83 B2O3 0.16
> P2O5 0.00
>Total 100.00 SiO2 2.14
>56.04%
> Fe2O3 0.00
>
>Si:Al 6.27 Expansion 7.28
>
>SP2M
>
>Frit 3134 24.00 18.32% CaO 0.49*
> Li2O
>0.13*
>Spodumene 24.00 18.32% MgO 0.29*
>Barnard clay 8.00 6.11% K2O 0.01*
>Goldart 8.00 6.11% Na2O 0.09*
>Dolomite 26.00 19.85% TiO2 0.01
>Zircopax 10.00 7.63% ZrO2 0.11
> EPK 16.00 12.21% Al2O3 0.30
>13.29%
>Flint 15.00 11.45% B2O3 0.16
> P2O5
>0.00
> SiO2
>2.03 52.23%
>Totals 131.00 100.00 Fe2O3 0.04
>
>Si:Al 6.67 Expansion 6.22.
>
>The first ( t1-12) fires very well at cone 4 with a nice smooth matte finish .
>This glaze was developed using Ian Currie's suggested methodology. The second
>glaze (SP2M) is a modified Zakin glaze and at Cone 4 runs completely off
>the pot
>and sticks to the shelf.
>
>Both appear to be within suggested limits for cone 4 and the amount of
>Al2O3 is
>almost identical in both formulae. I used my trusty Insight program and the
>glazes were fired side by side on the shelf with witness cones
> Simply put why does the one run and the other not?
>
>Your guidance and advice will be eagerly awaited and appreciated
>
>Thanx MoCain .
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Craig Martell on tue 21 mar 00
ron roy sezed:
>There was a version from Foote that melted much lower than this current
>variety - it's much darker in the powdered form and fires quite glassy and
>brown. If that is what you used I would not be surprised by the extra
>melting - just melt some on a tile - of it's brown glass (lots of iron)
>them get some of the currently available spod.
>
>Perhaps Craig Martel will send you an analysis for the impure foote stuff -
>I'm packing for NCECA now and I'm running short of time.
Hi:
Here is the analysis for Foote Chemical Grade Spod.
SiO2 63.0%
Al2O3 24.8
Fe2O3 2.0
K2O 1.18
Na2O .60
Li2O 5.70
I've seen other analyses of this material that give the Fe2O3 value at 4.0%
so factor in some variation if you use this material. Also, the
silica/alumina ratio is 4.32.
regards, Craig Martell in Oregon
Hank Murrow on tue 21 mar 00
Dear Mo; As Ron suggests, do a fusion button test; just pack a thimble with
the material in question and set it on a tile and tap it and lift the
thimble off. Fire to your glaze temp. Hey! If that 'dirty' spodumene
doesn't do good things for you, give it to a potter who does "Modified
American Shino". They will love you for it......great firecolor. Hank in
Eugene
>----------------------------Original message----------------------------
>Hi Mo,
>
>They are very similar - either you left out some thing - maybe the EPK??? -
>better try it again.
>
>the other explanation could be the kind of Spod you use. I am using one
>that is available now - from Tanko which is very close to the Ausi Spod
>avail in the US.
>
>There was a version from Foote that melted much lower than this current
>variety - it's much darker in the powdered form and fires quite glassy and
>brown. If that is what you used I would not be surprised by the extra
>melting - just melt some on a tile - of it's brown glass (lots of iron)
>them get some of the currently available spod.
>
>Perhaps Craig Martel will send you an analysis for the impure foote stuff -
>I'm packing for NCECA now and I'm running short of time.
>
>RR
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