Katharina Schulz on fri 31 mar 06
Hi there,
I have been learning the Seger-Calculation in Japan at a glaze class,
and everything
was clear and fine, and I could do all my calculations. But now I am
back in Germany
and I need to calculate my recipes with new ingredients.
But there is a little problem, since the composition of each ingredient
is different, the largest of all problems is that Cornish Stone has a
high percentage on Al2O3 and K2O.
And calculating first NaKO, MgO, CaO to 1, then calculating Kaolin
Al2O3, leaves me
with Cornish Stone for SiO2.
Here would stop the Japanese calculation happily, because the stone
powder used there
has very little of other elements.
But Cornish Stone, which I have to use in Germany, has despite of SiO2
also 11% Al2O3 and 7% K2O, which can't be dismissed! So I remember from
my old schooldays that there was something like interpolation if there
are two unknown variables.
Looking through the internet, I couldn't understand a thing, since it
was too abstract,
and not glaze related so I was totally lost. Is anyone here, who could
help me learning interpolation?
I know most of you would use a program to make the calculation for you,
but I like to understand it myself :)
As an example here is a glaze recipe I have worked on:
=====================================================
0.25 KNaO }
0.4 CaO 0.3Al2O3 3.2SiO2
0.35 MgO
=====================================================
____________________________________________________________________
0.25 KNaO Feldspat - Kali
____________________________________________________________________
KNaO (want)/ KNaO (is) = n Faktor
KNaO (want) 0.25 / KNaO (is) 0.221108143 =
1.130668443 FACTOR
multiply with Factor
SiO2 1.096505824 * Factor 1.239784532
Al2O3 0.182352941 0.206180716
Fe2O3 0.000438322 0.000495597
CaO 0.007130125 0.008061807
MgO 0 0
____________________________________________________________________
0.35 MgO Talkum
____________________________________________________________________
MgO (want)/ MgO (is)
MgO (want) 0.35 / MgO (is) 0.76426799 +
0 =0.457954545
Factor
multiply with Factor
SiO2 0.865224626 * Factor 0.39623355
Al2O3 0.052941176 0.024244652
Fe2O3 0.01377583 0.006308704
CaO 0.016042781 0.007346864
____________________________________________________________________
0.4 CaO Kalkspat
____________________________________________________________________
CaO (want)/ CaO (is)
CaO (want) 0.4 / CaO (is) 0.994652406 +
0.008061807
0.007346864
= 0.396015656 Factor
multiply with Factor
SiO2 0.011647255 * Factor 0.004612495
Al2O3 0.001960784 0.000776501
Fe2O3 0.000626174 0.000247975
====================================================
------------------------------------------------------------------------
----------------------
0.3 Al2O3 Kaolin
------------------------------------------------------------------------
----------------------
Al2O3 (want)/ Al2O3 (is)
Al2O3 (want) 0.3 / Al2O3 (is) 0.811980033 +
0.206180716
0.024244652
0.000776501
= 0.287581676 Factor
multiply with Factor
SiO2 0.811980033 * Factor 0.233510579
Fe2O3 0.003757044 0.001080457
------------------------------------------------------------------------
----------------------
3.2 SiO2 Cornish Stone
------------------------------------------------------------------------
----------------------
SiO2 (want)/ SiO2 (is)
SiO2 (want) 3.2 / SiO2 (is) 1.351081531 +
1.239784532
0.39623355
0.004612495
0.233510579
= 0.992179552 Factor
multiply with Factor
Fe2O3 0.000626174 * Faktor 0.000621277
Al2O3 0.108823529 0.107972481***
KNaO 0.117700842 0.116780369***
!!!!!!!!!!!!!!!!!!!!!!! and here lies the problem
!!!!!!!!!!!!!!!!!!!!!!!!
Cornish Stone has a high percentage of Al2O3 and K2O, how can I
approximate my calculation better? If I would use these numbers, my
glaze result would be totally wrong...
Does any of you do interpolation??
Your help would be very much appreciated :)
Thanks Kathy
Taylor Hendrix on fri 31 mar 06
Mein Gott Katharina! I'm befuddled.
Tell me if I am understanding your delima. You are using your
ingredients to supply oxides to your Segar formula, but by the time
you get to filling your SiO2 you don't have any "room" for other
oxides because you're sourcing silica from Cornish Stone. Did I
understand you correctly?
If so,why aren't you sourcing your SiO2 from flint/silica? Glazers
leave SiO2 to fill last because they have a very pure source for it in
flint.
I don't think of Cornish Stone as a silica source, I think of it as a
flux source.
And you got me on interpolation.
If I were to do pencil and paper calculations from a Segar Formula, I
would use all my percent analysis for all my ingredients to get their
own unity formulas. What's cool is that you can make your ingredient
unity formula based on ANY oxide. It's a preportion thing so it won't
matter. Then calc a molar weight for your ingredient. It is hurting
my brain right now, and I can't imagine what it is doing to yours, but
happily you can turn to Hamer's _The Potter's Dictionary of Materials
and Techniques_ and read the entries for 'calculation'. Great stuff.
Hals- und Beinbruch! (yuck)
Taylor, in Rockport TX
http://wirerabbit.blogspot.com
http://wirerabbitpots.blogspot.com
http://clayartmugshots.blogspot.com
Katharina Schulz on sat 1 apr 06
Sei gegr=FC=DFt Taylor,
thanks a lot!! You have saved me!!!!!!!!!!!!!!!!!!!!!
I never saw flint on my Molar mass list (may be because it is pure
SiO2).
And I was so fixed on that list, that it didn`t came into my mind to
have a look a little further in the delivery magazine. I just know all
the Japanese names for ingredients that I have to learn the European
nomenclature and ingredients new...
and you most certainly helped me a lot and saved me a looooooooot of
time.
Now I know, thanks to you, to use Flint as a silica source... now my
world is again in
proper order ;)
Dir auch noch ein gutes Gelingen
Vielen Dank
Kathy
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Taylor
Hendrix
Sent: Saturday, April 01, 2006 7:08 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Seger Calculation - Interpolation Help!
Mein Gott Katharina! I'm befuddled.
Tell me if I am understanding your delima. You are using your
ingredients to supply oxides to your Segar formula, but by the time
you get to filling your SiO2 you don't have any "room" for other
oxides because you're sourcing silica from Cornish Stone. Did I
understand you correctly?
If so,why aren't you sourcing your SiO2 from flint/silica? Glazers
leave SiO2 to fill last because they have a very pure source for it in
flint.
I don't think of Cornish Stone as a silica source, I think of it as a
flux source.
And you got me on interpolation.
If I were to do pencil and paper calculations from a Segar Formula, I
would use all my percent analysis for all my ingredients to get their
own unity formulas. What's cool is that you can make your ingredient
unity formula based on ANY oxide. It's a preportion thing so it won't
matter. Then calc a molar weight for your ingredient. It is hurting
my brain right now, and I can't imagine what it is doing to yours, but
happily you can turn to Hamer's _The Potter's Dictionary of Materials
and Techniques_ and read the entries for 'calculation'. Great stuff.
Hals- und Beinbruch! (yuck)
Taylor, in Rockport TX
http://wirerabbit.blogspot.com
http://wirerabbitpots.blogspot.com
http://clayartmugshots.blogspot.com
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