Hendrix, Taylor J. on thu 15 apr 04
Howdy doodie:
In the spirit of transparency I here offer an opaque base glaze I have
been testing. This glaze began its life as a Segar formula. Wanting a
glaze with zinc as a flux, I started with this:
CaO 0.3
MgO 0.2
K2O 0.2
Na2O 0.2
ZnO 0.1
Al2O3 0.4
SiO2 4
Using pencil and paper, I figured out the recipe using analysis info
where I could. Below is the glaze I am now playing with and the ideal
unity formula (still don't have the dough for a program) from a demo
program:
Custer 28.3
Neph Sy 11.7
Talc 11.5
Wolly 10.6
Zinc Ox 02.4
OM-4 07.8
Silica 27.4
CaO 0.32
MgO 0.33
K2O 0.13
Na2O 0.12
ZnO 0.10
Al2O3 0.33
SiO2 4.07
[Si:Al: 12.3]
Some room to drop the silica in this glaze as well. I make no claims to
the suitability of this glaze for any work.
My first round of testing was just to see some basic colorant responses
over two of my clay bodies. It didn't shiver off the test pieces so I
went ahead and made some colorant added batches and will have something
to look at about 2:30 tomorrow afternoon. The glaze is not runny at
cone 6, is opaque and crazes on Cinco Blanco from Armadillo. It did
show texture on the darker (Buffalo Wallow) clay body. Behaves okay in
the bucket, with sandy sediment forming quickly. (Talc?) No hard
panning, rather soft pan easily stirred. Sorry no s.g. information for
you. I did add 1% Bentonite to today's batch. Have 4%Cu, 10%Rutile,
and 4%Fe versions cookin' as I type. Oh boy a kiln full of vases; not a
single bowl.
Feel free to make observations if you so desire.
Taylor, in Waco
Paul Lewing on fri 16 apr 04
on 4/15/04 6:15 PM, Hendrix, Taylor J. at Taylor_Hendrix@BAYLOR.EDU wrote:
> In the spirit of transparency I here offer an opaque base glaze I have
> been testing. This glaze began its life as a Segar formula. Wanting a
> glaze with zinc as a flux, I started with this:
Taylor, we're proud of you! You're going to get this yet!
I'd have just one suggestion for you, based on my having done exactly what
you just did a few years ago (although I used software to do the math). I
also wanted a glaze with zinc as a flux, so I made up a Seger formula, and
then made a recipe from that. I managed to get it so right the first time
that I have put that glaze recipe into production and used it ever since
with no changes from that first try.
But here's my suggestion: if you want a glaze with zinc as the flux, go for
it. You've set your ZnO at a relatively low level. It's enough to show
some of the zinc characteristics, but not real strongly. The set of limit
formulas that I use says that at cone 5, the upper limit for ZnO would be
0.25 moles, so when I did mine, I set it at 0.5. I'm not saying you should
set yours that high, but mine works just fine at 0.5, and its response to
colorants is quite different from a more normal glaze. I've never had it
tested for stability, but it passed the vinegar test OK. I could give you
the recipe for mine, but I know neither of us wants me to do that. But if I
were you, I'd kick that zinc up a bit.
Paul Lewing, Seattle
David Hendley on fri 16 apr 04
I love you, man.
A guy who is making the effort to learn glaze formulation using
molecular formulae and calculating batch recipes!
On his own, not in a class!
By hand, with pencil and paper, no less!
Of course, this is how it should be done, and how we learned in
the '70's. In those days, we were excited when cheap and readily
available calculators came on the scene and we could hang up our
slide rules.
Just as you learn to do multiplication by hand before you use a
calculator, every glaze designer needs to know how to do it
with arithmetic before exclusively using a computer.
Taylor will be ceramically well served for the rest of his career
by his working knowledge of glaze chemistry.
David Hendley
david@farmpots.com
http://www.farmpots.com
----- Original Message -----
In the spirit of transparency I here offer an opaque base glaze I have
been testing. This glaze began its life as a Segar formula. Wanting a
glaze with zinc as a flux, I started with this:
CaO 0.3
MgO 0.2
K2O 0.2
Na2O 0.2
ZnO 0.1
Al2O3 0.4
SiO2 4
Using pencil and paper, I figured out the recipe using analysis info
where I could. Below is the glaze I am now playing with and the ideal
unity formula (still don't have the dough for a program) from a demo
program:
Custer 28.3
Neph Sy 11.7
Talc 11.5
Wolly 10.6
Zinc Ox 02.4
OM-4 07.8
Silica 27.4
Ron Roy on sat 17 apr 04
I have heard this before - that it would be helpful to know how to do it by
hand before using a calculator.
In the case of learning to use a glaze calculation program I don't see how
it can help.
I used a slide rule in school to calculate glazes - before calculators -
gave up because I could never get the same answer twice. Yes - I am
mathematically challenged - can't spell worth a damn either, have a
terrible memory and many other short comings. None of which have hampered
my ability of how to understand a glaze.
I could not tell you how to calculate a glaze by hand - in fact would never
stipulate that you should and see it only as a deterrent to actually
deciding to learn about using calculation software and understanding about
glazes.
On the other hand - I have nothing but admiration for those who do
calculations by hand. I just don't think it a necessary step - particularly
when computers do the job so well and so fast.
So please - don't think for a minute that you need to know how to do it by
hand - I can think of nothing that would discourage most of you more.
RR
>Just as you learn to do multiplication by hand before you use a
>calculator, every glaze designer needs to know how to do it
>with arithmetic before exclusively using a computer.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Christy Pines on sat 17 apr 04
From someone who's only been "potting" for 1.5 years, can you tell me why zinc so attracted you?
christy in connecticut who just put up 6 new shelves in my house to hold the results of the salt kiln. makes me smile just to look at them
Paul Lewing wrote:
I also wanted a glaze with zinc as a flux,
Paul Lewing on sat 17 apr 04
on 4/17/04 8:41 AM, Ron Roy at ronroy@CA.INTER.NET wrote:
> I could not tell you how to calculate a glaze by hand - in fact would never
> stipulate that you should and see it only as a deterrent to actually
> deciding to learn about using calculation software and understanding about
> glazes.
I've heard Ron say this before, and I'm always really glad to hear it. I
have at times in my life known how to calculate a Seger formula by hand, but
I couldn't tell you how to do it now. I always tell people in my glaze
workshops this, and then I tell them that I figure if it's OK that Ron
doesn't know how, it's OK for me not to know.
But I do think it's really important to know how those numbers were arrived
at, even if you can't actually do it. It's important to know what they
represent. You don't necessarily need to know the mathematical steps
involved, but you need to know what numbers you'd start with, and how you'd
use them to arrive at the end numbers.
But knowing how to do it mathematically can only increase your
understanding. It may or may not be unnecessary, but it's never a
liability.
Paul Lewing, Seattle
Fara Shimbo on sun 18 apr 04
Hi, Ron and all,
I was taught to make glazes by calculation too, by hand the
hard way (I was much better at using my slide rule as a
lethal weapon than as a calculating device...)
But I've found that as much "fun" (in a warped sort of way)
carefully calculating a glaze is, I have much better success
sitting thinking, "Okay, this is what I want. I'll add ...
let's see ... 50% this ... and okay, 3% this ... and..."
Sometimes I don't know why I'm putting in Ingredient X, I
just feel like this is what I should use.
The glazes I carefully claculate out are fine, the work and
are nice but never spectacular. The ones I just come up with
out of (seemingly) nowhere are often truly amazing.
Maybe there's a Secret Glaze Calculator hidden somewhere in
my brain that Knows These Things. I find that hard to believe
since for just about all other purposes my brain is utterly
useless.
Was just wondering if anyone else out there has this happen...
Fa
--
=============================================================
Fara Shimbo, Master Crystalliere, Certified Public Nuisance
-------------------------------------------------------------
Shimbo Pottery, PO Box 41, Hygiene, CO 80533 USA 720.207.5201
Crystalline-Ceramics.Info ShimboPottery.com Crystallieri.Org
Klysadel.Net TuranianHorse.Org
=============================================================
John Hesselberth on sun 18 apr 04
On Sunday, April 18, 2004, at 10:12 AM, Fara Shimbo wrote:
> Maybe there's a Secret Glaze Calculator hidden somewhere in
> my brain that Knows These Things. I find that hard to believe
> since for just about all other purposes my brain is utterly
> useless.
>
> Was just wondering if anyone else out there has this happen...
Hi Fara,
I bet the reason your calculated glazes are only nice is that you are
staying within traditional 'limits'. While the silica and alumina
limits are important if you want stable glazes, the limits on
individual fluxes should be considered 'open season'. For example if
you want a high calcium glaze don't stop at 0.7 calcium where the
limits stop--push it to .85 or 0.9 or even higher if you can get there
and see what happens. I'm betting, in your more spectacular glazes, you
have done that intuitively. The traditional limits are simply a
collection of 'where most glazes are' and have little, if any,
scientific basis (except for silica and alumina).
John
http://www.frogpondpottery.com
http://www.masteringglazes.com
Ron Roy on sun 18 apr 04
Hi Taylor,
Hey - thats pretty good - I get the following from your recipe.
CaO 0.34
MgO 0.31
K2O 0.13
Na2O 0.12
ZnO 0.10
Al2O3 0.33
SiO2 4.07
[Si:Al: 11.9]
As you can see - it's probably our analysis of Talc and/or wollastonite
that differ, I'mm not surprised that the clay analysis is off - OM#4 is all
over the place - always has been.
I'm pretty sure it will not be transparent though - not enough zinc to melt
it properly at cone 6. Do a line blend adding ZnO now to get the right
amount of fluxing.
The MgO is near the upper limit and it is a stiffner so it may interfer
with the transparency.
Expansion is good - this will not craze on most cone 6 clays . I have
calculated all the expansions for our glazes and have ritten them below
each recipe - they will serve as a good guide to getting the expansions
right for your glazes.
My hat is off to you - RR
>In the spirit of transparency I here offer an opaque base glaze I have
>been testing. This glaze began its life as a Segar formula. Wanting a
>glaze with zinc as a flux, I started with this:
>
>CaO 0.3
>MgO 0.2
>K2O 0.2
>Na2O 0.2
>ZnO 0.1
>
>Al2O3 0.4
>SiO2 4
>
>Using pencil and paper, I figured out the recipe using analysis info
>where I could. Below is the glaze I am now playing with and the ideal
>unity formula (still don't have the dough for a program) from a demo
>program:
>
>Custer 28.3
>Neph Sy 11.7
>Talc 11.5
>Wolly 10.6
>Zinc Ox 02.4
>OM-4 07.8
>Silica 27.4
>
>
>CaO 0.32
>MgO 0.33
>K2O 0.13
>Na2O 0.12
>ZnO 0.10
>
>Al2O3 0.33
>SiO2 4.07
>[Si:Al: 12.3]
>
>Some room to drop the silica in this glaze as well. I make no claims to
>the suitability of this glaze for any work.
>
>My first round of testing was just to see some basic colorant responses
>over two of my clay bodies. It didn't shiver off the test pieces so I
>went ahead and made some colorant added batches and will have something
>to look at about 2:30 tomorrow afternoon. The glaze is not runny at
>cone 6, is opaque and crazes on Cinco Blanco from Armadillo. It did
>show texture on the darker (Buffalo Wallow) clay body. Behaves okay in
>the bucket, with sandy sediment forming quickly. (Talc?) No hard
>panning, rather soft pan easily stirred. Sorry no s.g. information for
>you. I did add 1% Bentonite to today's batch. Have 4%Cu, 10%Rutile,
>and 4%Fe versions cookin' as I type. Oh boy a kiln full of vases; not a
>single bowl.
>
>Feel free to make observations if you so desire.
>
>Taylor, in Waco
>
>______________________________________________________________________________
>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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Earl Krueger on sun 18 apr 04
On Sunday, Apr 18, 2004, at 07:12 US/Pacific, Fara Shimbo wrote:
> The glazes I carefully claculate out are fine, the work and
> are nice but never spectacular. The ones I just come up with
> out of (seemingly) nowhere are often truly amazing.
Fara,
Just curious. Have you ever tried, through calculation,
to determine what makes your amazing glazes amazing?
In other words, are they amazing because you are pushing
the limits on some component or another, or are they
amazing because they fall right in the middle?
Would be interesting to know.
Earl K...
Bothell, WA, USA
Ron Roy on mon 19 apr 04
Hi Fara,
Yes I do think some of us are better at mixing materials together and
getting more interesting glazes - certainly David Shaner was one of the
best.
As Earl K said - calculating those made up glazes will give you an even
better idea about where to go next time.
Your technique when calculating probably involves using published limit
formulas and that tends to make glazes have a similarity. What you need are
new limits - you will find them in your "made up" glazes.
Notice the high calcium mattes in our book - Calcium Oxide is way over the
limits.
Some one once said on ClayArt - I want unusual glazes - without realizing
that calculation can be used to get anything you are interested in and
includes the understanding which leads to even better results - no mater
what kind of glazes you want.
RR
>I was taught to make glazes by calculation too, by hand the
>hard way (I was much better at using my slide rule as a
>lethal weapon than as a calculating device...)
>
>But I've found that as much "fun" (in a warped sort of way)
>carefully calculating a glaze is, I have much better success
>sitting thinking, "Okay, this is what I want. I'll add ...
>let's see ... 50% this ... and okay, 3% this ... and..."
>Sometimes I don't know why I'm putting in Ingredient X, I
>just feel like this is what I should use.
>
>The glazes I carefully claculate out are fine, the work and
>are nice but never spectacular. The ones I just come up with
>out of (seemingly) nowhere are often truly amazing.
>
>Maybe there's a Secret Glaze Calculator hidden somewhere in
>my brain that Knows These Things. I find that hard to believe
>since for just about all other purposes my brain is utterly
>useless.
>
>Was just wondering if anyone else out there has this happen...
>
>Fa
>--
>=============================================================
>Fara Shimbo, Master Crystalliere, Certified Public Nuisance
>-------------------------------------------------------------
>Shimbo Pottery, PO Box 41, Hygiene, CO 80533 USA 720.207.5201
>Crystalline-Ceramics.Info ShimboPottery.com Crystallieri.Org
>Klysadel.Net TuranianHorse.Org
>=============================================================
>
>______________________________________________________________________________
>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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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