Martin Howard on tue 9 oct 01
We need formulas, not recipes, whether weighed in parts which add up to 100,
or done with potter's percentages, or parts by volume.
When you put recipes on Clayart you automatically cut out those of us who
have different RMs or the same named RMs but obtained from different
locations.
Recipes do not travel. Formulas do.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
This web-site is about to be updated.
vince pitelka on tue 9 oct 01
> We need formulas, not recipes, whether weighed in parts which add up to
100,
> or done with potter's percentages, or parts by volume.
> When you put recipes on Clayart you automatically cut out those of us who
> have different RMs or the same named RMs but obtained from different
> locations.
> Recipes do not travel. Formulas do.
Martin -
With all due respect, this is not a practical or wise suggestion. Formulas
allow you to compare and reproduce the main glaze oxides, but they do not
take into consideration the trace minerals in many of the raw materials.
You cannot duplicate the glaze unless you have the recipe. Then at least
you have a shot at substituting appropriate materials for ones which are not
available to you, which will get you a hell of a lot closer to the original
glaze than calculating back from the formula using your raw materials. That
will likely give you a very different glaze. The ideal is to have both
recipe and formula, but given the choice of one or the other, you will have
better luck with the recipe.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Martin Howard on wed 10 oct 01
Vince advises me to put up with recipes appropriate materials for ones which are not available to you>
We have had many instances on the list of potters following the recipes and
coming up with something completely different. I did one which completely
ruined a bucket of glaze! One of many of course.
No, Vince, sorry to disagree with you, but I will stick to formulae, plus my
RMs which are all analysed.
Your way works within the continent of North America where you can all get
the same RMs and speak the same language:-)
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
This web-site is about to be updated.
David Hewitt on wed 10 oct 01
I agree with Vince that the recipe is the starting point in
communicating a glaze, but it is indeed a help if we also have the
analysis based on the user's raw materials. We can then decide if we
wish to adjust the recipe to suit our sources.
After the firing temperature or cone and the firing atmosphere, the next
most important thing is the clay body that the user uses. This can make
a vast difference to the outcome of the glaze.
I am assuming that a description of the glaze has been given at least in
terms of shiny, matt etc. and a colour description. All factors which
are to some extent subjective judgements and open to different
interpretations. They are necessary, however, as we cannot transmit
images with a Clayart message.
Transporting glazes is not straight forward and just giving a recipe
leaves a lot to be desired. I have tried to set out these points on my
web site under the heading 'Transporting' Glazes and if anyone ask me
for details of the glazes I illustrate I try to give the maximum
information on the above lines.
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
vince pitelka on wed 10 oct 01
> Vince advises me to put up with recipes > appropriate materials for ones which are not available to you>
> We have had many instances on the list of potters following the recipes
and
> coming up with something completely different. I did one which completely
> ruined a bucket of glaze! One of many of course.
> No, Vince, sorry to disagree with you, but I will stick to formulae, plus
my
> RMs which are all analysed.
> Your way works within the continent of North America where you can all get
> the same RMs and speak the same language:-)
Martin -
I am certainly sympathetic to this problem, and I can understand your
dissappointment when a bucket of glaze gets ruined. But isn't it always
standard practice to test a small quantity of a new glaze before mixing up a
large quantity? The chemical analysis of any North American raw material is
readily avaialable online, and if you have the recipe you can use those
chemical analyses to comparison shop among your available raw materials in
order to find the closest substitute, and you can also easily calculate a
formula if you prefer that. At least that way you stand a chance of getting
a glaze which is close to the original, whereas with the formula alone you
will rarely get a glaze which is very close to the original. Of course, a
good way to come up with new variations on a glaze is to calculate back from
the formula, trying different raw materials combinations to supply all the
glaze oxides, but it does not sound like that is your intent here. I am
sorry, but I cannot see how working from a formula without the recipe could
be any advantage at all.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Earl Brunner on thu 11 oct 01
All this talk about Seger formulas vs. recipe. If I see a glaze that I
like or want to try, I want the recipe. I want to know what was used on
the sample I'm seeing. If I don't have some of the materials, than my
second choice is, "Do I want to try to get the same result with
substitutions?"
A good case in point would be Gerstley Borate. As it has become less
available and the supply runs out, we turn to our favorite glazes that
have it as an ingredient and try to find a replacement. Anyone that has
done this over the last year or so will tell you that substitutions
don't always yield the same results. Even if the finished product looks
similar, there are different problems, (in this case we often have
turned to frits, w/cost & settling problems).
If we are just pulling formulas out of the air without any visual to
see, we may be wasting a lot of time and effort.
--
Earl Brunner
http://coyote.accessnv.com/bruec/
bruec@anv.net
Martin Howard on thu 11 oct 01
Vince you are talking me round to your point of view.
But let's have both formulae and recipes (with a statement of just where
those RMs came from).
Then I need some more cone 1-2 glazes to work on. Quite rare on Clayart.
Of course we should always test, test, test before making a big batch.
But some of the descriptions on Clayart were so enticing that enthusiasm
overcame other thoughts:-)
Result, buckets of glaze that need some detailed work before they are of use
again.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
This web-site is about to be updated.
Alisa og Claus Clausen on thu 11 oct 01
I have to wonder.
Isn't is it more or less true that no matter what you have on a piece of
paper or the back of your hand, you must mix the glaze, see what you get on
your clay, in your kiln, and then figure out what you need to do?
Tony H, John H, Tom B. Ron R. and a few others have my greatest respect and
admiration and everything else superlative positive with regards to glaze
formulation and sharing information.
They also say (to a degree or more so) that glaze recipes to not travel
well. That was, as I understand it, the basis for Tony's 20 x 5 recipe. A
jumping off recipe so those who try, can tinker around and get the glaze
they want from this ground recipe. I appreciate that theory. I use 20 x 5
just as it written for a clear. It works for my clay. I add all kinds of
additives for colors and surfaces.
I am an American educated ceramist that lives in Scandinavia. I have only
recipes. I have different materials at hand than I had in the USA. I use
recipes from Ababi in Isreal, from all over the US, from South Africa and
more. How do they work? Some work with the materials I have that are
called the same, but mined in different areas. Some work with a slightly
educated guess on a sub. Some work but they I do not like them. Some do
not work because they have a fault like crazing, and I would not accept
that as an "effect".
I started up my studio here a few years ago with deadpan premixed
glazes. I had to do something to get on with it.
(My favorite Mel-ism). I did not wah wah because no one came and said,
here, Alisa, 10 great glazes with recipes including materials you can dig
up in your back yard. I started testing 100 gram batches of everything I
thought looked reasonable. It takes time, costs money in materials and I
had to get really organized with my day, space and budget. However, after
ca. 300 tests, over 100 worthwhile to report to Clayart, I have a
reasonable pallet of glazes.
I wonder how many ClayArters use recipes successfully, not because they
struck gold with the first try, but test and adjust all the time to get the
results they need with their materials, their clay and their kiln.
I will bet many, many.
I am no glaze academic. But, by testing, studying results, researching
materials and their effects, advice from Clayart, books, etc, I am coming
along quite nicely, thank you very much!! My guessing gets more academic
with each kiln load.
So, all this rambling. Martin, you are not going to get spoon fed. You
are not going to get a formula and it is going to be a wonderful working
glaze each time, every time. You know that. You can try recipes with your
materials and get to work to adjust to your needs. No one is being cut out
by recipes. You are cutting yourself short by turning a blind eye to
recipes. How can I have success as an American in Denmark with American
recipes? I am not cut out, I am cutting myself in by biting the challenge
because I have a need. Decent glazes.
You are entitled to your opinion, that is of course all right. But we have
been around this block already. Being stubborn sometimes gets in the way
of opening great possibilities.
For now and for the foreseeable future ( I am repeating myself from the
last round of this discussion)
I send recipes and my results, as objectively as possible. I am pretty
sure some people find this useful.
I have always used any recipe primarily as a jumping off point. Sometimes
it is bingo, sometimes it is garbage, sometimes I need to try it out on a
different clay, different application and sometimes I need to work it out.
My only advantage is that I like to test. I think it is interesting. I am
born the "working child". I got to have my pile at the end of the
day. These tiles look like little marchers in a glaze parade.
Great day today, Autumn, sunny and crispy! I am going to "harvest" the
Ginko leaves today.
Best, all the best, regards, Alisa in Denmark
Mike Gordon on thu 11 oct 01
Vince,
Where would one look on line for raw material analysis? Is there one
place or do you go by material name,etc.? Mike Gordon
Marianne Lombardo on thu 11 oct 01
I turned to mixing glazes from scratch because the commercial jars of glazes
were not working well for me at ^6. They were pinholing, cratering, and
colours were totally different from the colour samples. Commercial glazes
are expensive. If they don't work anyway, what was the point in buying
them. My money is better spent learning a bit of glaze chemistry and
experimenting with mixing my own. At least now, most of my surprises when I
open the kiln are good surprises! And it's exciting and fun. I'm not a
chemist and there is no way I could understand a "formula", but give me a
"recipe", now that's different. At least it makes a bit of sense. When I
cook meals, I follow a basic recipe but also have learned to make my
own changes, depending on my tastes and needs. Same theory for glazes. My
Christmas "wish list" to my family is a glaze software program so I can
learn more.
Seriously, glazes recipes don't seem to travel all that bad at all. Maybe
the results aren't exactly the same as the person originally posting, but
all in all I have, with a lot of help from my friends here in Clayart, now
have half a dozen glazes that work consistently for me that I like. And a
few more
that I still need to work on. Lots of testing needed of course. Now I've
learned to test on a very small pot of some sort that I can use if good or
throw out if not good. Right now I'm trying to learn how to tone a high
shiny gloss down to a more satin, less shine gloss.
I enjoy seeing postings from people that have tested recipes, and learning
about their results. It gives me the encouragement to try them for myself.
I do not expect to get the same results, but if I do, and if I like it,
that's wonderful and I label that recipe as a keeper. A keeper for me,
maybe someone else won't like it or get the same results.
Glaze layering seems to me to be the real magic. Alisa taught me how to
layer glazes. With her help, I've learned a few combinations that work well
for me. Twice-firing as well - some amazing results. Learning that was
accidental. I had some pots I didn't like and experimented with reglazing.
Glaze a pot with a nice brown, like Tenmoku Gold II and fire to ^6. Then
reglaze using 20x5 with 12% tin oxide and fire again to ^6 with slllooowww
cooling - wow! Swirly browns and whites in a lovely satin gloss. Looks
great on large bowls, not so good on a mug. Shapes of the pots seem to have
a lot to do with it. My assumption is that the glaze sits still a bit
longer on a gradual curved shape, and flows faster on a vertical surface.
????
Alisa, what are Ginko leaves?
Marianne
going outside now to rake up some leaves, harvest my squash, and the green
tomatoes...
Cindy Strnad on thu 11 oct 01
Formulas are fine, if you've got the raw material
analysis and a copy of a good glaze software on
your computer. If you don't, please don't feel you
can't post simply because you don't have glaze
software. Most of us appreciate your input. You'll
get comments as to the likely stability of your
glaze--it's a good thing. We like you and
appreciate your sharing.
I don't have the analysis (because I haven't taken
the trouble to request it), but I do have Insight,
so I post the formulas when I'm copying from
Insight because it makes some people feel better.
Of course, if they've got Insight, they can get
pretty much the same numbers from their program
that I get from mine. At any rate, their numbers
will be as good as mine, even if they're slightly
different. Unless you input the analysis for each
bag of spar, etc., it's just a rough guess anyway.
So, fair notice: the numbers in the formulas I
post with my glazes are standardized. I have not
copied down the analysis into Insight for every
bag of raw materials I buy. I could, but I don't
want to.
If you fire at ^2, then get some glazes formulated
for ^2, test them, and post the results. I'm sure
lots of people out there would like to know. I
don't fire at ^2. While I'm willing to share
knowledge I already have, I'm not going to test a
bunch of ^2 glazes as research for someone else
who is capable of doing the research himself. I
expect a lot of us feel the same way.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com
vince pitelka on thu 11 oct 01
> Where would one look on line for raw material analysis? Is there one
> place or do you go by material name,etc.? Mike Gordon
Mike -
Just go to http://www.digitalfire.com/education/material/index.html - this
is Tony Hansen's wonderful ceramic materials database at the Digitalfire
website. Just enter any material in the search box and it brings up
description, chemical analysis, etc.
As you know, Tony sells his Insight and Foresight software, his Magic of
Fire book, and various other products at the Digitalfire website, but there
is also an enormous amount of great information about materials, base
glazes, glaze formulation, etc.
Best wishes -
- Vince
vince pitelka on fri 12 oct 01
> This is because - if you have the recipe you have the formula - all same
if
> you have the formula you have the recipe.
Wow, here it is, the moment when I disagree with Ron Roy, whose opinions on
all things glaze related I hold so dearly. If you have the formula, you do
not have the recipe, because you have no way of knowing how thorough and
accurate the sender was in preparing the formula from the recipe. If you
have the recipe, you can prepare the formula yourself. Otherwise, the
formula leaves out so much.
> The key here is having the analysis for the materials.
Exactly.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
David Hewitt on fri 12 oct 01
Mike,
That is correct, but it will give you a typical analysis. For many
purposes this is OK, but my own experiences last year showed me that one
should be wary of what one buys as it is not always the same.
Last year I bought some talc from a different supplier which resulted in
a quite different result when used in any glaze. Subsequently I got an
analysis sheet from the new supplier and the original supplier. This
clearly showed very significant differences.
The second example I came across was with Black Iron oxide.
If you really want to know what you are using get an analysis sheet from
your supplier. Any good supplier should be happy to let you have this.
If you are interested, full details about the talc and black iron oxide
can be found on my web site under 'Raw Materials - Do you know what you
are buying'.
David
In message , vince pitelka writes
>> Where would one look on line for raw material analysis? Is there one
>> place or do you go by material name,etc.? Mike Gordon
>
>Mike -
>Just go to http://www.digitalfire.com/education/material/index.html - this
>is Tony Hansen's wonderful ceramic materials database at the Digitalfire
>website. Just enter any material in the search box and it brings up
>description, chemical analysis, etc.
>
>- Vince
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Ababi on fri 12 oct 01
..Following Earl Brunner
---------- Original Message ----------
>All this talk about Seger formulas vs. recipe. If I see a glaze that I
>like or want to try, I want the recipe. I want to know what was used
on
>the sample I'm seeing. If I don't have some of the materials, than my
>second choice is, "Do I want to try to get the same result with
>substitutions?"
>A good case in point would be Gerstley Borate.
>Earl Brunner
>http://coyote.accessnv.com/bruec/
>bruec@anv.net
..>All this talk about Seger formulas vs. recipe.
I did not take part in this thread. I thought: "They will discuss, and
I will do. Tony Hansen blue with materials he never seen Cindy dark
brown on clay never passed the English Canal Steve Mils violet with a
feldspar that did not pass the Sues canal and so on.
This morning from 07:00 O'clock I started to watch the temp going down,
287C, 286C 285C. In 16:00 I opened the kiln grabbed the hot test tiles
and drove home on my mini tiny electric cart.
The first time I made Fall Creek Shino
>A good case in point would be Gerstley Borate. As it has become less
>available and the supply runs out, we turn to our favorite glazes that
>have it as an ingredient and try to find a replacement. Anyone that
has
>done this over the last year or so will tell you that substitutions
>don't always yield the same results. Even if the finished product
looks
>similar, there are different problems, (in this case we often have
Here is the original recipe:
Cone: 6
Color: Opaque Tan-breaking red
Testing: Tested
Surface texture: Shiny or Glossy Glaze name: Fall's Creek Shino
Firing: Oxidation
Glaze type:
Recipe: Percent Batch
Gerstley Borate 18.69 18.69
F-4 Feldspar 9.35 9.35
Alberta Slip 56.07 56.07
Lithium Carb 6.54 6.54
Silica 9.35 9.35
Totals: 100.00 % 100.00 gm
Also add:
Zircopax 9.35 9.35
Tin Oxide 4.67 4.67
The way it is written, probably from the Ceramic Web.
My version
Falls2
GERSTLEY BORATE..... 17.2 15.06%
LITHIUM CARBONATE... 6.3 5.54%
SILICA.............. 15.2 13.36%
RED CLAY............ 38.6 33.83%
FRIT 3110........... 10.6 9.27%
DOLOMITE............ 6.3 5.54%
WOLLASTONITE........ 2.1 1.89%
ENGLISH KAOLIN CC31. 3.7 3.21%
ULTROX.............. 9.4 8.20%
TIN................. 4.7 4.10%
========
114.0
CaO 0.38* 7.64%
Li2O 0.25* 2.65%
MgO 0.18* 2.55%
K2O 0.07* 2.43%
Na2O 0.12* 2.72%
TiO2 0.01 0.42%
ZrO2 0.14 6.27%
Al2O3 0.28 10.11%
B2O3 0.22 5.44%
SiO2 2.64 56.88%
Fe2O3 0.05 2.87%
Si:Al 9.55
SiB:Al 10.33
Expan 6.58
"My" red clay has 7% Iron
Very nice indeed.
Today I was disappointed, but for nothing. Reading these two recipes,
brings me to the calculation that the substitution I made this time -
for
the G B was successful. The problem was that I did not add
the Zircopax 9.35 and the Tin Oxide 4.67 So I got a clear glaze.
My red clay is similar to yours redart.
So here Falls3
FALLS CREEK SHINO3
==================
LITHIUM CARBONATE... 6.87 6.87%
SILICA.............. 13.45 13.45%
RED CLAY............ 42.75 42.75%
LAGUNA BORATE....... 16.96 16.96%
FRIT 2120........... 7.48 7.48%
TALC................ 5.14 5.14%
WOLLASTONITE........ 7.34 7.34%
========
100.00
CaO 0.38* 8.42%
Li2O 0.25* 2.92%
MgO 0.18* 2.83%
K2O 0.07* 2.64%
Na2O 0.13* 3.12%
TiO2 0.02 0.49%
Al2O3 0.28 11.14%
B2O3 0.22 6.03%
SiO2 2.49 59.27%
Fe2O3 0.05 3.14%
Text1 11.44
Si:Al 9.03
SiB:Al 9.82
Expan 7.02
I used frit 2120 because it has lower cost 3110 is fine
Now through Insight Fall Creek4>>> Back to the USA:
FALLS CREEK SHINO4
==================
LITHIUM CARBONATE... 6.7 5.83%
SILICA.............. 6.4 5.58%
LAGUNA BORATE....... 15.4 13.46%
TALC................ 4.5 3.98%
WOLLASTONITE........ 7.0 6.16%
FRIT 3110........... 13.3 11.61%
REDART.............. 41.7 36.59%
EPK KAOLIN.......... 5.1 4.43%
ULTROX.............. 9.4 8.24%
TIN OXIDE........... 4.7 4.12%
========
114.1
CaO 0.38* 7.70%
Li2O 0.25* 2.64%
MgO 0.18* 2.55%
K2O 0.07* 2.26%
Na2O 0.13* 2.86%
TiO2 0.02 0.48%
ZrO2 0.13 5.95%
Al2O3 0.28 10.13%
B2O3 0.22 5.42%
P2O5 0.00 0.10%
SiO2 2.64 57.01%
Fe2O3 0.05 2.92%
Si:Al 9.56
SiB:Al 10.34
Expan 6.59
From Ababi Having a screen saver with a picture of "Falls Creek fall
from state park Tennessee" Something to do with this lovely glaze?
So their might be life after the GB!
Ababi Sharon
Kibbutz Shoval- Israel
officially Glaze addict
sharon@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
Ron Roy on fri 12 oct 01
>You cannot duplicate the glaze unless you have the recipe.
This is not true - I have made glazes substituting materials - using the
formula - in fact I do it every day it seems. If you have accurate analysis
you may even have the trace elements as well.
I have made series of glazes - same glaze with completely different
materials that all behave the same.
Now I am not saying it is foolproof - I admit to having had to learn the
hard way the little tricks that help the process. Particle size is a
consideration as well.
The point in the long run is - If you have even semi accurate analysis for
your materials and theirs you can do it from the recipe OR the formula.
This is because - if you have the recipe you have the formula - all same if
you have the formula you have the recipe.
The key here is having the analysis for the materials. The trick to having
good analysis is the sticky point here. Not all the analysis for Cornwall
stone are the same because there are different kinds, not all the analysis
for Gerstley Borate are the same so you have to make adjustments and that
is where the skill comes in.
When you get an analysis from a book or a data base you must assume it is
wrong for a number of reasons - typos are one - authors get them from other
books and then the typo gets repeated - the person typing numbers into the
data base is tired and bored and gave up double checking a hundred
materials ago - I say go to the mine but even then double check till you
are reasonably certain you have the right one, or two or three. In the case
of GB - you should have at least three to give a range. I got some bad
numbers from a frit company once - has sodium and potassium numbers
reversed. I caught it because I was cross checking a data base - In the end
- I have to say - don't trust anyone. I guess that makes my data base
better than theirs.
In either case - recipe or formula - if the analysis are not right for the
materials you are dealing with - you have to figure it out.
The one thing you must have is a way of calculating the formula - and the
best way to do that is with calculation software.
RR
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Ron Roy on wed 17 oct 01
My statement was in responce to the flat out statement that you cannot
duplicate a glaze from the molecular formula - That is not true.
As I have explained - accurate analysis are the key.
I have done it many times - well thousands of times - like all those GB
recipes for instance.
RR
> If you have the formula, you do
>not have the recipe, because you have no way of knowing how thorough and
>accurate the sender was in preparing the formula from the recipe. If you
>have the recipe, you can prepare the formula yourself. Otherwise, the
>formula leaves out so much.
>
>> The key here is having the analysis for the materials.
>
>Exactly.
>
>Best wishes -
>- Vince
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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