Glaze Calculation Software - understanding what they are showing.

[Min]

@Pyewackette tagged me in  this thread with what I think is a really good question.  "@Min Really what I'm looking for are materials to help me understand what the calculators are showing me." 

Given that some of us likely use glaze calc for different reasons; perhaps it's to swap out a material and keep the UMF the same or make a matte glaze more glossy or looking at ratios or to simply look at oxide levels, or … ? I thought it would be good to start a thread on this and not just give my thoughts in the other thread. What features of the glaze calc software do you use that are the most useful? Do you use more than one feature? How helpful do you find it? Would you explain what the feature(s) you use are showing and why that’s useful.

Another question I would ask would be do you think it's important to have a basic understanding of which materials supply which oxides before you started using glaze calculation software or did you pick that up more so after you started using it?

Edited April 25, 2022 by Min

[neilestrick]

I've forgotten half of what I knew about glaze formulation, because I just don't do much of it any more. But when I do need to do some tweaking of a glaze, I use glaze formulation software. I've used Hyperglaze since I started making pots in 1992, and it has worked well for me. Back then it was the only system for Mac users and I never found a good reason to switch to anything else. I first learned to calculate UMF by hand, which I think is a great way to understand what's happening when the software is making those calculations for you, but unless you're pretty comfortable with math it will most likely make things more confusing. A good understanding of the materials is more important IMO.

Even if you're not super knowledgable about glaze formulation, the software (whatever brand) is a great way to catalog your glazes in a format that gives you lots of information beyond just the simple recipe. It will also calculate batch sizes, which is a big help for folks who aren't handy with math.

I rarely calculate a glaze from scratch. It's just not necessary with all the glaze recipes available on the interwebs, plus I have a database of like 800 recipes that I've built up for the last 30 years. Instead, I find something that's close to what I need and tweak it as necessary. I was trained to work with the UMF, so that's what I do. Most of my tweaks involve substituting ingredients to use what I keep in inventory, and adjusting melt, glossiness, and COE.

I think the best way to begin to understand glaze formulation is to first find a good book or online tutorial on the subject that lays it out in simple terms- fluxes, stabilizers, glass formers. When I was in school we did not have such a book, only more technical tomes that were somewhat difficult to understand. But in the last 20 years there have been some great ones that make it easier to understand. From there you just have to jump in and start doing it. Test, test, test. In my 2 1/2 years of grad school I ran about 3,000 test tiles, and that really built on the foundation the books gave me and made me fluent in the glaze language. Glaze formulation has come a long way since I first learned it, and we're much more aware of the benefits of making durable glazes, whereas we used to be far more focused on jsut safety and leaching. I think glaze safety is probably the most difficult thing to learn, but again the newer books address that much better than the old classics.

[Callie Beller Diesel]

I started out with more material knowledge, because my first glaze chem instructor taught the class more like cooking than like chemistry. I drove the man nuts because I wanted more scientific answers, and he didn’t have them to give me.

I started off with Clay and Glazes for the Potter, and did a few longhand UMF calcs. I’ve always had a good grasp on proportion and ratio math, which is all we’re really working with. I didn’t get too in depth with the math then, because I did’t have easy access to materials analyses to do them for everything. This was also around 2000-2001.

I really disliked making so many test tiles, because while there’s something to be said for the hands on method, repeating the same thing that’s been done and documented so well somewhere else seemed like a waste of time. But I didn’t really know where to access that information. Where I’m at, no one was really using glaze software in my earlier days. It existed and I knew other people used it, but no one I knew personally did. 

I enjoy chemistry and I wasn’t satisfied with what I knew, so about 10 years ago I sat through all of Tony’s tutorials on Insight, and figured out how to use it. I still have a subscription there, but at the time I found the learning curve on the software steep. I found Glazy much easier to figure out, but at this point I don’t know if that’s because I already knew materials and how to use one glaze calc software already. Both those programs do have manuals that teach you how to use them. 

That said, I like Digitafire’s database better, because it’s got more materials provenance and links to some additional information.

I think if I was starting out all over again, I’d want to start with a high school understanding of chemical reactions being a matter of proportions between the individual molecules, and the idea that if a glaze falls within certain proportional ranges, it *should* behave in a certain way. Also, acknowledging that the math will narrow down your test field, but not eliminate it entirely. I’d then move to Glazy as a software, but go and read about each material in my chosen glaze on Digitalfire to understand what was going on more. I’d also add Hamer and Hamer to the reference list. If I wanted to go beyond that, I’d take Matt Katz’s course.

[Min]

I started out with learning materials first also. My instructors were old school at didn't use glaze calc software so it was the old calculator and pen and paper method of working out UMF (unity molecular formula). I remember there was a lot of moaning and groaning about having to do math in art class and honestly we didn't spend much time on it. (If anyone is interested in how to do this there is a good video here explaining it.) Fast forward a few years and I became aware of Insight, can't remember what year it was but the program came on a floppy disc and I've used it since then. Insight underwent a couple major changes since and I now use it on a Mac. Regardless of using a software program or not having an understanding of what materials contribute to a glaze is going to speed up the learning process. Lots of good materials source information available either online or in texts.

Circling back to @Pyewackette's question of what a program shows. Given that I use Insight I'll use that as an example. Insight doesn't include Stull Charts but like Callie said thats available for free with Glazy.

So just touching on the basics of what software will display and what can be changed. (I'm not going to explain in detail what each section means, that info is easily searched also.) I pulled a cone 6 clear recipe off Glazy that had a lot of materials as a demo glaze.

Red box - this is the recipe, it can be totalled to whatever amount you want to mix up a batch. The amounts of each material can be increased or decreased.

Blue box - I have set this program to show "Auto Unity" this is a UMF.  There are other options on which unity is used but I won't go into that here.

Under the "Ratios" heading there are:

Orange Box: this is the Si:Al (silica to alumina) ratio. Generally speaking if a glaze is high in silica in this ratio it will be low in alumina therefore one would expect the glaze to be glossy. Reverse that and have a glaze low in silica and high (relative) in alumina and it will probably be on the matte side. There are other contributing factors to what makes a glaze gloss or matte though but for a straight forward glaze without a surplus of calcium, zinc, strontium, barium etc can also matte up a glaze. (getting back to knowing your materials)

Green Box: this is the SiB:Al (silica + born to alumina) ratio. Boron can gloss up glazes even with high alumina amounts so this can be handy to see. 

Black Box" this is the R2O:RO (alkali metal fluxes to alkaline earth fluxes) There is wiggle room here but a flux ratio of 0.3 : 0.7 is often a sign of what will be a durable glaze. (with qualifications) Good article by Linda Bloomfield here, includes an abbreviated Periodic Table showing which elements are useful to potters and explains the alkali fluxes and alkaline earth fluxes.  

Under Expansion header is the Purple Box. This shows the COE (Coefficient of Thermal Expansion) sometimes called CTE. This can be useful to see for fully melted gloss glazes. As a true matte glaze will have some oxides that separate out from the glaze matrix it does't work for matte glazes. I find it is super useful when trying to reduce crazing (or shivering) in a gloss glaze.

Gray Box: this is showing the LOI (loss on ignition). Shows how much will burn out of the glaze during firing. This can matter in glazes that have pinhole issues. 

Format will be different with other programs and might or might not include the same info.

I'm just going to add one simple quick demo of how this type of software is useful. Using the same glaze recipe I'm going to pretend I'm out of Wollastonite but I do have Calcium Carbonate (aka Whiting). I know Wollastonite contains calcium + silica and Calcium Carbonate contains calcium.

First recipe: "Marc's Clear ^6" is how it appears above. 

Second recipe: I replaced the Wollastonite with Calcium Carbonate in exactly the same amount. Have a look at he Unity though, it's thrown the numbers off. Most noticeably the calcium is higher and the silica is lower. To fix this I need to lower the Calcium Carbonate and increase the silica.

Third recipe: I've lowered the Calcium Carbonate so the calcium (CaO) is the same as in the original formula. I then bumped up the silica to match original formula. This changed my total from 100 so I re-totalled it to 100. Have a look at the Unity formulas now. See how the first and third formulas are identical? As are the ratios. You can also see that by swapping the Calcium Carbonate for the Wollastonite the LOI has increased.

This is just one simple demo of what you can use glaze software for.  For fun try plunking a recipe into Glazy and do a simple change like this one and see what you come up with.

 

Edited April 26, 2022 by Min

[Pyewackette]

Wow!  So much to take in, LOL!  I have to get a notebook and start taking notes.  

Hope I haven't lost my math chops.  Diffy-q was a looooong time ago ... Chemistry, even longer LOL!

[Clay17]

Great post Min, easily understood and well written.

18 hours ago, Min said:

You can also see that by swapping the Calcium Carbonate for the Wollastonite the LOI has increased.

How can the increase of LOI effect this glaze?

[PeterH]

11 minutes ago, Clay17 said:

How can the increase of LOI effect this glaze ?

LOI (Loss on Ignition) https://digitalfire.com/oxide/loi

Edited April 27, 2022 by PeterH

[Pyewackette]

@Callie Beller Diesel I'm afraid I have the same mindsight - its not enough for me to know something works.  I want to know WHY it works that way, and why it doesn't work when it fails.  Apparently that's not the norm. But I feel like without the background of the whys and wherefores, it's just stumbling around in a dark room with a blindfold on and your ears plugged. 

I seriously do need to get a notebook and start taking notes like I'm in class.  I have so many things bookmarked that I can't easily find something I already read, nor adequately associate related information.  

Just right this second I think I'll just take a nap.  I have a long drive there and back again tomorrow, nap again Sunday, and start fresh Monday.  Plans!  I love 'em!

[Hulk]

On why, some of the sources that have helped me (and still are):

This forum, there's a variety of "takes," dedicated knowledgeable contributors, where just about everything pottery has an archive.

Several books, some periodicals, pick one, that'd be Susan Peterson's The Craft and Art of Clay; her unity section was the "oh, I get it now, thanks" for me.

Tony Hansen's articles (digitalfire.com) so helpful, e.g.
Concentrate on One Good Glaze (digitalfire.com)
I'll say there's an argument for trying several glazes as well, where one gets direct experience with more materials - more time, expense, and learning.
Crazing in Stoneware Glazes: Treating the Causes, Not the Symptoms (digitalfire.com)
High Gloss Glazes (digitalfire.com)
Bringing Out the Big Guns in Craze Control: MgO (G1215U) (digitalfire.com)
G1214Z (digitalfire.com)
That last is "Silky Matte" with links to other matts, etc., do you hear me there.

Just using the software - I'm using Hesselberth's GlazeMaster* - each number has meaning, row and column.

Mixing up glaze batches and trying them. I keep up with recycling clay and cleaning up fairly well, but have avoided circling back on doing something with abandoned glaze batches...

*Looks like there are ways to read Apple Books on non Apple devices; I'm a getting my own copy of his book and port it to my reader!

Edited April 30, 2022 by Hulk
naps are good!

[PeterH]

6 hours ago, Hulk said:

Several books, some periodicals, pick one, that'd be Susan Peterson's The Craft and Art of Clay; her unity section was the "oh, I get it now, thanks" for me.

Cheaply available second-hand, adjust this search for your location and currency
https://tinyurl.com/mw873skd

I found the  second half of Ian Currie's book - which examines several important glazes -- very interesting. Especially as it reflects that there are many mechanisms that make glazes interesting. Online at https://wiki.glazy.org/t/ian-curries-stoneware-glazes/367

[Callie Beller Diesel]

@Pyewackette if you have a few dollars to spend on it, Rose and Matt Katz have several colleges level online glaze course that goes as in depth as you could like at Ceramic Materials Workshop, There are bundles, and options that allow you to do a lecture-only version for somewhat less money. They also have a podcast called For Flux’s Sake that has some good free info too. 

[Retxy]

for hyperglaze users, why do excesses of different oxides present with negative numbers and in red in the unity formula? I am not sure why an excess would produce a negative number, unless i am missing something with the scientific notation? I feel rather stupid. and also, why must I be forced to use the calculation function instead of manually adjusting the ingredients myself? Is there a way around this?

 

Thanks SO much! If there is a better place to post this, please let me know. 

 

 

[Hulk]

Hi Retxy,
Was curious enough to find this video clip collection HyperGlaze - glaze software for artists but not enough to watch them, or install the software.
My guess would be the presentation reflects the limit set, and the limit set is likely configurable.
Perhaps someone who uses the software will yet reply, bump!

I'm using GlazeMaster; it has a compare to limit formulas view, which I do look at, if not very often. I'm using the unity/weight/mole view more.
Am also using Glazy (Glazy.org an online glaze resource) R2O:RO ratio calculator; adjusting the ratio seemed key to resolving my low expansion liner glaze issues. 

[neilestrick]

15 hours ago, Retxy said:

for hyperglaze users, why do excesses of different oxides present with negative numbers and in red in the unity formula? I am not sure why an excess would produce a negative number, unless i am missing something with the scientific notation? I feel rather stupid. and also, why must I be forced to use the calculation function instead of manually adjusting the ingredients myself? Is there a way around this?

 

Thanks SO much! If there is a better place to post this, please let me know. 

 

 

Are you working in the Glaze Calculator section?

When you put in an ingredient that fulfills the requirements for certain oxides, but overloads other oxides, it shows as a negative number because it's showing how much you still need to fulfill. Needing a negative amount means you have too much of it.

As for the calculate button, that's just how the program works. It's doing the work for you. If you want a certain material to only supply a portion of what it could use, then you can put a precent in the 'Use' column as a decimal.

Materials need to be put into the calculator in order from most complex to least complex, and starting with your source of Boron, or it will be forced to overload oxides. If you put silica in first, it will fulfill all the silica, and then if you put in feldspar next it will over-fill the silica as it fulfills the other oxides that feldspar has. Here is the order in which you need to put things in:

1. Source of Boron, either a Frit or Gerstely Borate or equivalent

2. Feldspar or other Frits

3. Any material that contains 2 oxides, such as Wollastonite or Dolomite

4. Materials that only contain 1 oxide, such as Whiting, Magnesium Carb, Zinc Oxide, etc.

5. Clay

6. Silica

If you do things in this order, you'll have very little overloading of any single oxide, at least not enough to matter.

[Min]

I wonder why Hyperglaze makes it more difficult than it needs to be in regards to order of materials added? Seems like it would rely on people having knowledge of materials before using the calc. If an oxide is needed to be overloaded, like for a magnesium matte for example, do you just ignore the overload? Seems like the program was written when Limit Charts were more widely used.

[Retxy]

8 hours ago, neilestrick said:

Are you working in the Glaze Calculator section?

When you put in an ingredient that fulfills the requirements for certain oxides, but overloads other oxides, it shows as a negative number because it's showing how much you still need to fulfill. Needing a negative amount means you have too much of it.

As for the calculate button, that's just how the program works. It's doing the work for you. If you want a certain material to only supply a portion of what it could use, then you can put a precent in the 'Use' column as a decimal.

Materials need to be put into the calculator in order from most complex to least complex, and starting with your source of Boron, or it will be forced to overload oxides. If you put silica in first, it will fulfill all the silica, and then if you put in feldspar next it will over-fill the silica as it fulfills the other oxides that feldspar has. Here is the order in which you need to put things in:

1. Source of Boron, either a Frit or Gerstely Borate or equivalent

2. Feldspar or other Frits

3. Any material that contains 2 oxides, such as Wollastonite or Dolomite

4. Materials that only contain 1 oxide, such as Whiting, Magnesium Carb, Zinc Oxide, etc.

5. Clay

6. Silica

If you do things in this order, you'll have very little overloading of any single oxide, at least not enough to matter.

This helps more than words can say. THANK YOU SO MUCH!!! 

[Retxy]

7 hours ago, Min said:

I wonder why Hyperglaze makes it more difficult than it needs to be in regards to order of materials added? Seems like it would rely on people having knowledge of materials before using the calc. If an oxide is needed to be overloaded, like for a magnesium matte for example, do you just ignore the overload? Seems like the program was written when Limit Charts were more widely used.

I agree and I hardly know what I am doing. I tried to use the USE column to force what I wanted but it didn't work for me. I have been using glazy for the calculations then entering the recipe into hyperglaze to get an estimated COE for the glaze, which I haven't found a way to do in glazy. Also, hyperglaze does not do r20:ro, so even when I am using hyperglaze calculator to figure things out for me, I still have to enter it into glazy to get these, because I tried to manually calculate but was too... ahem  dumb... to figure out how. Also tried to calculate coe manually and was getting huge numbers. so hyperglaze has helped with that!

I am going to try what @neilestricksuggested, and see if this will make a difference for me. I kept wondering why the program would stop calculating when there were still two ingredients left in the list of the recipe after using sort, but now I see this was just because I had met the limits. At least i think!

 

Thanks again so much for all being willing to share their knowledge. so very appreciated

[Bill Kielb]

3 hours ago, Retxy said:

estimated COE for the glaze,

You won’t find an estimated COE in Glazy because at best it indicates a trend among similar glazes with similar chems. Fired COE or the melted glaze will end up to be it’s own COE not necessarily resembling the calculated. IMO, not useful to design with and often encourages flux substitution. There are those that report success with it as a trend indicator though as they are adjusting their glazes to fit their clay. The tendency is to start substituting lower expansion fluxes for higher. It’s a method, is it best? I am not sure really.

if you can afford I would suggest the Katz course. Even if the online version as it takes a materials approach which I think can be simpler in many respects to some of the traditional stuff you are working with now. Besides you will learn cone theory, a bit about colors and of course glaze defects as well as boron and of course a bit about Stull. Very helpful in IMHO and it will answer some of your current questions.

Edited June 20, 2022 by Bill Kielb

[Min]

1 hour ago, Bill Kielb said:

You won’t find an estimated COE in Glazy

Unless it’s been recently removed it is available at the Patron level on Glazy.

Just like Stull charts it’s another tool in the toolbox that many people find useful.

[Bill Kielb]

9 minutes ago, Min said:

Unless it’s been recently removed it is available at the Patron level on Glazy.

Hmm, thanks! Been a member for a long time, never have seen it. I’ll check!  Yes, it is a tool some folks really like.

[neilestrick]

22 hours ago, Min said:

I wonder why Hyperglaze makes it more difficult than it needs to be in regards to order of materials added? Seems like it would rely on people having knowledge of materials before using the calc. If an oxide is needed to be overloaded, like for a magnesium matte for example, do you just ignore the overload? Seems like the program was written when Limit Charts were more widely used.

When we say overloaded, it's not referring to limit charts. It's overloading what's needed in that particular glaze's unity formula.

[Min]

17 minutes ago, neilestrick said:

When we say overloaded, it's not referring to limit charts. It's overloading what's needed in that particular glaze's unity formula.

Just had a brief look at what HyperGlaze can do, I really like the function of it that shows if a glaze is likely to melt at the temperature given. Have you found that to be fairly accurate?

"The Glaze Limits card offers some of the most unique features of HyperGlaze - the ability to look at glazes in a more visual format. Here the glaze is represented by the light blue bars of the graph, while the limit formula for this type of glaze is represented by the colored bars behind. The light blue bars (your glaze) can be easily dragged up and down using the mouse to adjust each oxide. Keeping the tops of the light bluebars within the limits (colored bars) ensures that the glaze will likely melt at the temperature given. The flux oxides (RO section) automatically readjust to maintain unity when any oxide is changed. Silica and Alumina can be linked to stay in in a specific ratio when adjusting. Custom limits are available and can be added by the user. The firing cone for the glaze can be automatically changed to adjust the fomula of the glaze to melt at higher or lower temperatures. And now the percentage analysis is visible all the time, too."

[neilestrick]

1 hour ago, Min said:

Just had a brief look at what HyperGlaze can do, I really like the function of it that shows if a glaze is likely to melt at the temperature given. Have you found that to be fairly accurate?

"The Glaze Limits card offers some of the most unique features of HyperGlaze - the ability to look at glazes in a more visual format. Here the glaze is represented by the light blue bars of the graph, while the limit formula for this type of glaze is represented by the colored bars behind. The light blue bars (your glaze) can be easily dragged up and down using the mouse to adjust each oxide. Keeping the tops of the light bluebars within the limits (colored bars) ensures that the glaze will likely melt at the temperature given. The flux oxides (RO section) automatically readjust to maintain unity when any oxide is changed. Silica and Alumina can be linked to stay in in a specific ratio when adjusting. Custom limits are available and can be added by the user. The firing cone for the glaze can be automatically changed to adjust the fomula of the glaze to melt at higher or lower temperatures. And now the percentage analysis is visible all the time, too."

For the most part, yes. I think the limit for MgO is a little low- I have several good glazes that are beyond that limit- but it's a pretty handy function for plugging in a problematic glaze and seeing very quickly where things might be out of whack. I've used Hyperglaze for almost 30 years, and it has served me well. It does seem to calculate COE differently than Digitalfire, but since I only use Hyperglaze I've got a good baseline for comparing glazes.

[Callie Beller Diesel]

 

1 hour ago, neilestrick said:

It does seem to calculate COE differently than Digitalfire

It’ll be different in Glazy too. Sometimes wildly different. (They made the paid version free in May to encourage people to donate their patreon money to Ukrainians, so I was able to poke at the expanded access stuff a bit.)

For anyone not familiar, It’s not that the glaze software creators are doing bad math, it’s that the source numbers they have to use are pretty variable to begin with. You can measure an individual material’s COE with a dilatometer and get different values at different points in the firing. Change the firing, and you get different results again. Also, some materials like lithium and, I suspect, magnesium don’t expand linearly, and that messes with things too. Since it’s hard to get a pinpoint value, they have to either use a range, or base the math on an assumed set of conditions. It makes for funky finished glaze math. 

The one pottery supplier in Canada that I  know is still providing recommended glaze COE values for their clays  states that the numbers he uses are derived from Insight, but not everyone reads the fine print. I’ve seen it lead  to frustration. Calculated COE numbers are fine as long as you’re using the same measuring tool, much like a tape measure in a really precise carpentry project. If you switch tape measures, things aren’t going to line up the way you want them to.

 

 

[Min]

2 minutes ago, Callie Beller Diesel said:

The one pottery supplier in Canada that I  know is still providing recommended glaze COE values for their clays  states that the numbers he uses are derived from Insight, but not everyone reads the fine print.

I can see why this would be a problem! Claybodies are not supposed to melt. COE figures are based on a fulled melted glaze, with matte glazes since some of the oxides precipitate out of the glass matrix so even with a matte glaze the figures are not accurate. Clay bodies can't use COE figures from a glaze calculator to determine COE, need to use a dilatometer and even then the figures are only going to be somewhat accurate as the results are based on firing ramps that would need to be replicated fairly accurately. Dilatometer findings might get you in the ball park but still the old test, test, test. 

Where the makers of glaze calc programs get their data from is going to influence the COE (and all the other figures). We saw this with Custer feldspar for quite a few years. Garbage in garbage out.