Cindy on mon 12 jan 98
Hi, Guys.
I found this glaze on the Glaze Database and wonder how it stacks up?
Volcanic Ash 63.64
Gerstley 36.36
Total: 100.00
Add:
Tin Oxide 7.07
Bentonite 1.01
With the RO Unity turned on, I get:
CaO 0.74
MgO 0.04
K2O 1.01
Na2O 0.21
Fe2O3 0.02
B2O3 1.01
Al2O3 0.05
SiO2 2.88
Weight 308.36
Si:Al 58.75
SiB:Al 79.37
Expan 6.59
That's considerably different from the documentation that was listed with
the glaze. Am I doing something wrong here?
Also, if my levels are correct, is the high boron and low alumina a
problem? If not, I thought I might try it, then, if it works out, add some
rutile, cobalt, and perhaps a bit of manganese. Any thoughts?
Thanks for your help,
Cindy in Custer, SD
Knox113 on tue 13 jan 98
Hi Cindy,
I have been using this as a base glaze for years, with wonderful results. I
find it to be consistantly successful at cone 6 and cone 7 oxidation.
I have never used it alone but in concert with oxides. I'll be happy to share
info with you --just have to find it first. I moved recently and haven't
unearthed the glaze formulas yet. Just found the oxides today!!!
knox in Georgia where it's overcast,rain on the way but in the 60's.
Ron Roy on tue 13 jan 98
Hi Cindy,
First of all this formula is not in unity if it were then the CaO, MgO, K2O
and Na2O would add up to 1.0 - hence the name Seger"unity" molecular
formula.
It is crucial we know which volcanic ash you will use - great plains or Mt.
St. helens. They are different. My calculation uses Mt St Helens.
Note - my calculation says this glaze is short of SiO2 so it's durability
is questionable. The expansion is pretty good for most bodies - but adding
silica will lower it - perhaps too much for some bodies. It's probably a
soft glaze with alll that boron as well.
Untitled Recipe 2
-----------------
Volcanic ash........ 63.64 58.88%
Gers Borate 9/97.... 36.36 33.64%
TIN................. 7.07 6.54%
BENTONITE........... 1.01 .93%
----------
108.08
FORMULA & ANALYSIS
------------------
*CaO........ .54 10.63%
MnO2....... .00 .05%
*MgO........ .23 3.23%
*K2O........ .03 1.06%
*Na2O....... .21 4.52%
Fe2O3...... .07 3.74%
TIO2....... .01 .39%
B2O3....... .43 10.58%
AL2O3...... .34 12.33%
SiO2....... 2.18 46.17%
SnO2....... .14 7.30%
COST/KG 3.71
RATIO 6.37
EXPAN 458.39
WEIGHT 282.70
>Volcanic Ash 63.64
>Gerstley 36.36
>Total: 100.00
>
>Add:
>Tin Oxide 7.07
>Bentonite 1.01
>
>With the RO Unity turned on, I get:
>
>CaO 0.74
>MgO 0.04
>K2O 1.01
>Na2O 0.21
>Fe2O3 0.02
>B2O3 1.01
>Al2O3 0.05
>SiO2 2.88
>
>Weight 308.36
>Si:Al 58.75
>SiB:Al 79.37
>Expan 6.59
>
>That's considerably different from the documentation that was listed with
>the glaze. Am I doing something wrong here?
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
DONPREY on thu 15 jan 98
Ron,
I have about 75 pounds of Mt. Saint Helens ash sitting in the garage. If you
would send me the material analysis I would greatly appreciate it.
I've been following the Clayart list for 3 or 4 months now and do appreciate
the time and care you take to increase the general level of understanding of
the materials we all work with.
Don Prey in Oregon
Ron Roy on fri 16 jan 98
>----------------------------Original message----------------------------
>Ron,
>I have about 75 pounds of Mt. Saint Helens ash sitting in the garage. If you
>would send me the material analysis I would greatly appreciate it.
>I've been following the Clayart list for 3 or 4 months now and do appreciate
>the time and care you take to increase the general level of understanding of
>the materials we all work with.
>Don Prey in Oregon
Hi Don - I got a whole bunch of analysis of Mt St Helens ash from Michael
McDowell - he's on Clay Art so you could find him - he in in Bellingham
Washington - up near the Canadian border.
I jus did an average of them all - it depends where you picked yours up and
how long it was out in the rain - so this is not specific - but it will do
to help you make a glaze out of what you have - don't forget to factor in
the LOI of 0.77
Don't ask me why it totals 101.18 I don't know and can't stop now to try
to make sense of it - i do remember that many of his analysis were over and
some under - it will be good enough for you purpose.
Volcanic ash
------------
SiO2................ 63.74 63.00%
AL2O3............... 17.82 17.61%
TIO2................ .60 .59%
Fe2O3............... 5.46 5.40%
MgO................. 2.48 2.45%
MnO2................ .07 .07%
CaO................. 5.18 5.12%
Na2O................ 4.42 4.37%
K2O................. 1.41 1.39%
----------
101.18
FORMULA & ANALYSIS
------------------
*CaO........ .38 5.08%
MnO2....... .00 .07%
*MgO........ .26 2.43%
*K2O........ .06 1.38%
*Na2O....... .30 4.33%
Fe2O3...... .14 5.35%
TIO2....... .03 .59%
AL2O3...... .73 17.48%
SiO2....... 4.42 62.51%
L.O.I. .77
RATIO 6.08
EXPAN 449.51
WEIGHT 424.62
Notes: Average of Mt St helens ash from West Washington U 6/9/80
Sent by McDowell - see paper in "entered into MDT" file
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
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