Paul Lewing on tue 8 apr 08
On Apr 8, 2008, at 5:28 AM, Jim Brideman wrote:
I have several recipes that fire beautifully at a cone 8 that I
would like to try to convert to a cone 6.
You've gotten some good advice on this already, and I think I might
have a tidbit or two to add. You'll need some proficiency with your
glaze program and a set of limit formulas. As John said, you
probably are going to have to add additional flux, but to see if you
can get away without doing that here's what you do. You want to
keep all the fluxes exactly the same in the unity formula, and you
want to keep the alumna/silica ratio the same. This should ensure
that the surface stays the same degree of gloss or matte and the
color response stays the same. What you want to do is reduce both
the alumina and the silica, as I said keeping the ratio the same.
How much. you ask? Here's where your limit formulas come in.
Look at where the values for the alumina and the silica fall in a set
of limit formulas for cone 3-8 or so. If the value of the silica,
for instance, falls at the top of the limits, you want to take it
down to about the middle, because cone 6 would be about the middle of
that range. So for instance, if your limit formulas say you may have
2.0- 3.5 silica and at cone 8, your glaze has 3.0, you'd probably
want to take it down to about 2.8 or 2.7. That would mean that if
your original glaze had .30 alumina (just to make the math easy) your
Al:Si ratio is 1:10. so you'd need .28 or .29 in your cone 6
version. Make sense?
Often you find, especially if you're trying to make a glaze go down
more than two cones, that you can take out all of the alumina or all
of the silica, and you still haven't reached your target. Then you
do need to add additional fluxes. But the more new elements you add,
the less similar the new glaze will be to the old one. And, of
course, no matter what you do to a glaze, you very likely will change
the COE. Just as a general rule of thumb, what often works to reduce
the firing temperature of a glaze a cone or two is to replace the
feldspar with nepheline syenite. That's always worth a shot.
Good luck.
Paul Lewing
www.paullewingtile.com
Jim Brideman on tue 8 apr 08
Hi, I apologize if this is covered somewhere in the archives as I couldn't find it if it is. For a little background, I have MC6 and the Glazemaster software. I have several recipes that fire beautifully at a cone 8 that I would like to try to convert to a cone 6. I have tried firing them as they are at a cone 6 and the results are unsatisfactory. What I have seen here on clayart are specific recipes that have been converted but I would like to learn how to do this on my own using the software and some testing.
I understand that I would be looking at the unity formula of the original and trying to match it with the new recipe, but what would a logical sequence of steps to take in an attempt to do this? Sorry if this is a pretty basic question. I guess what I am looking for would be a step by step sequence to follow as a guideline or is it just a matter of substituting the current flux with a Frit for example and then matching the rest of the numbers?
Thanks in advance.
John Hesselberth on tue 8 apr 08
On Apr 8, 2008, at 8:28 AM, Jim Brideman wrote:
> Hi, I apologize if this is covered somewhere in the archives as I
> couldn't find it if it is. For a little background, I have MC6 and
> the Glazemaster software. I have several recipes that fire
> beautifully at a cone 8 that I would like to try to convert to a
> cone 6. I have tried firing them as they are at a cone 6 and the
> results are unsatisfactory. What I have seen here on clayart are
> specific recipes that have been converted but I would like to learn
> how to do this on my own using the software and some testing.
>
> I understand that I would be looking at the unity formula of the
> original and trying to match it with the new recipe, but what would
> a logical sequence of steps to take in an attempt to do this?
Hi Jim,
Moving a glaze a couple cones, like you want to do, can usually be
done without too much change in aesthetics. Moving farther can be
problematical.
If your cone 8 glazes already have some boron or zinc in them
increasing one of them is the first thing I would try. Most cone 6
glazes have roughly 0.2-0.3 B2O3 or ZnO -- one or the other, usually
not both. So look at your cone 8 glazes--if they are typical they may
well already have about 0.1-0.2 boron or zinc-- and adjust them
upward using glaze calculation software. About 0.05-0.06 of boron or
zinc per cone seems about right.
If they have no boron or zinc then they are probably cone 10 glazes
that have been "stretched" down to cone 8 and it is time to add one
or the other. Boron is most commonly used in North America. Zinc is
most commonly used in Europe. But be aware that zinc sometimes
affects color (e.g. muddy browns) in ways you may not like.
The other aspect to look after is how much the COE changes. Adding
boron will lower it. If you are already on the low side you might
want to make some minor adjustments in other oxides to bring it back up.
When I am trying to do this I always go a little beyond where I think
I need to be and then do a 5 part line blend to zero in on what I want.
I hope this helps get you started. Good luck.
John
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Jim Bridgeman on wed 9 apr 08
Thank you very much.
Jim Bridgeman on wed 9 apr 08
I think I accidently hit send before I finished typing.
Thank you very much. Here is my attempt at converting using the software
only. This is my first attempt at doing any conversions, so any feedback
or concerns anyone has would be greatly appreciated. I know that this is
just a small step with actual tests still to come.
The recipe I am trying to convert is on the bottom...the version I came
up with is on top.
Recipe Name: 382rev.nobar.(modified to cone 6)
Cone: 8 Color: brown
Firing: Oxidation Surface: Semimatte
Amount Ingredient
46 Feldspar--G-200
8 Whiting
4.5 Strontium Carbonate
7.5 Zinc Oxide
.5 Talc
9 Ball Clay--Old Mine #4
22 Flint
97.5 Total
Additives
10 Ilmenite--Powdered
Unity Oxide
.076 Na2O
.176 K2O
.017 MgO
.325 CaO
.101 SrO
.305 ZnO
1.000 Total
.357 Al2O3
.003 Fe2O3
3.127 SiO2
.004 TiO2
8.8 Ratio
75.5 Exp
Comments:
-----------------------------------
Calculations by GlazeMaster=99
www.masteringglazes.com
------------------------------------
Recipe Name: 382 revised with no barium cone 8
Cone: 8 Color: brown
Firing: Oxidation Surface: Semimatte
Amount Ingredient
47 Feldspar--Potash
9.5 Whiting
7 Strontium Carbonate
6 Zinc Oxide
2.5 Talc
10 Ball Clay--Old Mine #4
18 Flint
100 Total
Additives
10 Ilmenite--Powdered
Unity Oxide
.072 Na2O
.158 K2O
.062 MgO
.337 CaO
.146 SrO
.226 ZnO
1.000 Total
.326 Al2O3
.004 Fe2O3
2.874 SiO2
.005 TiO2
8.8 Ratio
76.4 Exp
Comments:
-----------------------------------
Calculations by GlazeMaster=99
Eleanora Eden on wed 9 apr 08
I just read Paul's excellent post and highly recommend the suggestions
he's made.
I have a chart of limit formulas that covers the whole range from ^010
up to ^12. It says Matrix.lim at the top, I either took it off his website
or had a test copy of Matrix glaze tech program and got it from there.
Handy chart. He gives a range, not a specific figure, for alumina and
silica. For alumina, ^6 is .21-.57 and ^8 is .25-.61. For Silica, ^6 is
1.9-4.2 and at ^6 it is 2.25-4.45.
Hope this helps.
Eleanora
>On Apr 8, 2008, at 5:28 AM, Jim Brideman wrote:
> I have several recipes that fire beautifully at a cone 8 that I
>would like to try to convert to a cone 6.
>
>You've gotten some good advice on this already, and I think I might
>have a tidbit or two to add. You'll need some proficiency with your
>glaze program and a set of limit formulas. As John said, you
>probably are going to have to add additional flux, but to see if you
>can get away without doing that here's what you do. You want to
>keep all the fluxes exactly the same in the unity formula, and you
>want to keep the alumna/silica ratio the same. This should ensure
>that the surface stays the same degree of gloss or matte and the
>color response stays the same. What you want to do is reduce both
>the alumina and the silica, as I said keeping the ratio the same.
>How much. you ask? Here's where your limit formulas come in.
>Look at where the values for the alumina and the silica fall in a set
>of limit formulas for cone 3-8 or so. If the value of the silica,
>for instance, falls at the top of the limits, you want to take it
>down to about the middle, because cone 6 would be about the middle of
>that range. So for instance, if your limit formulas say you may have
>2.0- 3.5 silica and at cone 8, your glaze has 3.0, you'd probably
>want to take it down to about 2.8 or 2.7. That would mean that if
>your original glaze had .30 alumina (just to make the math easy) your
>Al:Si ratio is 1:10. so you'd need .28 or .29 in your cone 6
>version. Make sense?
>Often you find, especially if you're trying to make a glaze go down
>more than two cones, that you can take out all of the alumina or all
>of the silica, and you still haven't reached your target. Then you
>do need to add additional fluxes. But the more new elements you add,
>the less similar the new glaze will be to the old one. And, of
>course, no matter what you do to a glaze, you very likely will change
>the COE. Just as a general rule of thumb, what often works to reduce
>the firing temperature of a glaze a cone or two is to replace the
>feldspar with nepheline syenite. That's always worth a shot.
>Good luck.
>Paul Lewing
>www.paullewingtile.com
--
Bellows Falls Vermont
www.eleanoraeden.com
Veena Raghavan on sun 13 apr 08
Would love to see how this is done, so I hope you will post it on Clayart.
Thanks in advance.
Veena
In a message dated 4/13/2008 4:50:44 PM Eastern Daylight Time,
ronroy@CA.INTER.NET writes:
>
>
> Hi Jim,
>
> Send me one of the recipes and I'll show you how to do it.
>
> If there is zinc then do a line blend increasing that.
>
> If there is boron then do a line blend increasing that - just keep
> everything else the same including the silica/alumina ratio.
>
> There is a lot more to this but you will learn as you go - and remember -
> when you are looking for something - don't ignore all the other things that
> will happen along the way.
>
> RR
>
VeenaRaghavan@cs.com
Ron Roy on sun 13 apr 08
Hi Jim,
Send me one of the recipes and I'll show you how to do it.
If there is zinc then do a line blend increasing that.
If there is boron then do a line blend increasing that - just keep
everything else the same including the silica/alumina ratio.
There is a lot more to this but you will learn as you go - and remember -
when you are looking for something - don't ignore all the other things that
will happen along the way.
RR
>Hi, I apologize if this is covered somewhere in the archives as I couldn't
>find it if it is. For a little background, I have MC6 and the Glazemaster
>software. I have several recipes that fire beautifully at a cone 8 that I
>would like to try to convert to a cone 6. I have tried firing them as
>they are at a cone 6 and the results are unsatisfactory. What I have seen
>here on clayart are specific recipes that have been converted but I would
>like to learn how to do this on my own using the software and some
>testing.
>
>I understand that I would be looking at the unity formula of the original
>and trying to match it with the new recipe, but what would a logical
>sequence of steps to take in an attempt to do this? Sorry if this is a
>pretty basic question. I guess what I am looking for would be a step by
>step sequence to follow as a guideline or is it just a matter of
>substituting the current flux with a Frit for example and then matching
>the rest of the numbers?
>
>Thanks in advance.
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on tue 15 apr 08
Hi Jim,
The bottom one is a cone 8 glaze and your conversion (top one) is the cone
6 version?
If so you will need less alumina and silica to have it melt at a lower
temperature - or introduce some fritted boron or any kind of frit for that
matter - because frits are already melted they help melt the glazes faster.
If you want the glaze to look the same it's better to keep the alumina
silica ratio the same - you have increased it in yours.
My #1 would be to raise the zinc by 2 and lower the Old Mine and silica by
1 each. The problem with that is the expansion is probably too high.
My #2 would be to sub in some spodumene for the some of the spar - like
this - to get the expansion down.
-----------------
G 200 SPAR.......... 20.00
AUSI SPOD........... 21.00
WHITING............. 9.50
STRONT CARB......... 7.00
ZINC OXIDE.......... 8.00
TALC................ 2.50
OM-4................ 8.00
SILICA.............. 24.00
----------
100.00
FORMULA & ANALYSIS
------------------
*CaO........ .28
MnO2....... .00
*Li2O....... .15
*MgO........ .06
*K2O........ .07
*Na2O....... .03
*ZnO........ .28
Fe2O3...... .00
TIO2....... .00
AL2O3...... .32
SiO2....... 2.66
P2O5....... .00
*SrO........ .13
RATIO 8.36
EXPAN 424.83
WEIGHT 260.52
Expansion is down to a reasonable level - ratio is the same as the original
- and more zinc for melting.
If #2 does not melt properly add more zinc and/or introduce a frit. Start
with 3134 and add a little at a time.
Any questions?
I don't keep a copy of the glazes I work on so if you need more include all
of this.
RR
>Thank you very much. Here is my attempt at converting using the software
>only. This is my first attempt at doing any conversions, so any feedback
>or concerns anyone has would be greatly appreciated. I know that this is
>just a small step with actual tests still to come.
>
> The recipe I am trying to convert is on the bottom...the version I came
>up with is on top.
>
>Recipe Name: 382rev.nobar.(modified to cone 6)
>Cone: 8 Color: brown
>Firing: Oxidation Surface: Semimatte
>Amount Ingredient
>46 Feldspar--G-200
>8 Whiting
>4.5 Strontium Carbonate
>7.5 Zinc Oxide
>.5 Talc
>9 Ball Clay--Old Mine #4
>22 Flint
>97.5 Total
> Additives
>10 Ilmenite--Powdered
>Unity Oxide
>.076 Na2O
>.176 K2O
>.017 MgO
>.325 CaO
>.101 SrO
>.305 ZnO
>1.000 Total
>.357 Al2O3
>.003 Fe2O3
>3.127 SiO2
>.004 TiO2
>8.8 Ratio
>75.5 Exp
>Comments:
>-----------------------------------
>Calculations by GlazeMaster=99
>www.masteringglazes.com
>------------------------------------
>
>Recipe Name: 382 revised with no barium cone 8
>Cone: 8 Color: brown
>Firing: Oxidation Surface: Semimatte
>Amount Ingredient
>47 Feldspar--Potash
>9.5 Whiting
>7 Strontium Carbonate
>6 Zinc Oxide
>2.5 Talc
>10 Ball Clay--Old Mine #4
>18 Flint
>100 Total
> Additives
>10 Ilmenite--Powdered
>Unity Oxide
>.072 Na2O
>.158 K2O
>.062 MgO
>.337 CaO
>.146 SrO
>.226 ZnO
>1.000 Total
>.326 Al2O3
>.004 Fe2O3
>2.874 SiO2
>.005 TiO2
>8.8 Ratio
>76.4 Exp
>Comments:
>-----------------------------------
>Calculations by GlazeMaster=99
>
>___________________________________________________________________________=
___
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here:
>http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.c=
om
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
| |
|
