Glaze Calculation Software - understanding what they are showing.

[Callie Beller Diesel]

Arg. Sorry. I worded that funny. It’s PSH, and they provide a suggested number for the glazes to be used on the clay body, not for the clay body itself. 

Here’s a link to their clay specs sheet, so you can see what I mean.  

Their fine print reads:

COE: coefficient of expansion information supplied is based on the crazing behaviour of 10 quality control glazes fired to cone 06, cone 6 or cone 10 having COE’s ranging from 6.29x10 e-6/*C to 8.87 e-6/*C as determined by Insight glaze calculation software. Fully fused glazes having a lower COE (as determined by Insight) than the value indicated are not expected to craze. While this information is useful in assessing glaze suitability. It is not definitive; actual testing under user firing conditions is strongly advised. 

 

That’s a LOT of caveats. 

[Min]

Thanks Callie! I read it wrong. Like you said a lot of caveats and very much open to debate! Starting with was there flux continuity between all glazes in a given range...

[Hulk]

GlazeMaster also calculates COE, which I've found handy when looking to reduce/eliminate crazing (in that one glaze, not so much for comparing different glazes*), where tweaking oxides brought the number down this much, which reduced crazing that much, hence gaining an idea how much more tweaking required, or perhaps major changes necessary, even starting over.

Any road, going through a few rounds of tweaking oxides, then starting over, bringing in a bit of lithium (via petalite) got me close, then a bit more petalite, a bit more talc, a bit more zircopax, voila!
I found the calculated COE numbers were helpful to the process.

*however, once fired and examined, then correlation/comparison can be made, where this glaze COE number appears about equal to that glaze COE number based on the craze pattern...

[Retxy]

On 6/20/2022 at 11:50 AM, 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."

 

I have found those little toolbars indispensable actually. They give me soemthing to shoot for at the very least, along with the hard and fast rules that I learned in MC6. I really like this fucntion. I haven't figured out if there is a custom levels area yet, which would be useful if there is a set of parameters that one likes to reuse often, but if its there I will find it.

 

 

On 6/20/2022 at 1:15 PM, neilestrick said:

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.

 

have you found that when going by the COE given by hyperglaze that  the glazes you produce with it generally do well on your clays? I would think that would be testament enough.  I don't know if you get your ware professionally tested, or if COE calculation can even be ordered with tests for durability (pretty sure those are two different processes) but it would be so cool if you have data. 

 

THANKS SO MUCH EVERYONE. This community is a lifesaver