Short description of Glaze Limits and Stull diagram (Free Online Glaze Class Pt. 3)

Short introduction of various ceramic glaze limits, brief overview of various glaze softwares and Stull diagram. This the the third video in the series.

[@kevinh5024]

Thank you for posting these. I've never really grasped the bigger picture of the Uni-molecular System. This has really clarified things a lot for me. Its awesome! I truly appreciate it. You are Mr Glaze, and a great teacher. Thanks again.

[@Neldidellavittoria]

This is flabbergasting. I see I need to study it and to start doing a lot of experimenting and sampling just to begin to understand it. Thank you very much indeed for all the time you put into doing these videos!

[@johnbrittpottery]

No you are fine as you are! Some people just like a more scientific approach so I'm trying to provide that to them but it's not necessary for you to live a fulfilling life

[@Neldidellavittoria]

@@johnbrittpottery Oh, I know. But it does spark my curiosity. Thank you for a very nice reply. :)

[@createlovehappy]

Mesh size totally matters. When I was an intern learning how to be the glaze tech, I sieved with 80 instead of 60 and the glaze acted differently in our kiln. It wasn’t disastrous just noticeably different.

[@alisaliskinclausen2474]

This lesson gives me confidence about my use of limits for durable glazes at cone 6 ox., which I got from John Hesselberth and Ron Roy's research for their book Mastering Cone 6 Glazes. So far has worked pretty well for me to predict results for tests. Silicon Boron ratio would be helpful from Insight. Watching this video multiple times, I have learned that I can continue to use the same limits but should learn how to plot and interpert them using Stull since I am using glazy now. I also thought Stull was something recently developed and now have much more information on that. Watching this, it seems like there are different languages for glaze analyses. Matrix, Insight and GlazeMaster and I should use the one I like, which is Insight. I would prefer not to use Stull, but I want to keep my glazes in one place now, glazy, instead of storing them mulitple sites. Now I know it is not all different information, but different ways of reading it. Is that right?

[@johnbrittpottery]

You got it Alisa. You can use whatever to inform your practice. I have one coming ...hopefully after Thanksgiving...to show how to understand Stull with practical examples. Firing now.

[@EarthNationCeramics]

this is alot of info, i love it. would you mind going a little deeper on the cone system? i liked the example of .5/5.0 means cone 5 how would you know the cone of something that is silica11/21 alumina? is there math behind it? would you show us how to calculate it?

[@johnbrittpottery]

Calculated by moles.

[@YAYKUTTEL]

Good to hear the criticisms youve been airing in a slightly more public forum.

[@johnbrittpottery]

I am not hiding...believe me. I just had to devote time to doing this..got more coming. I just find it confusing ..not for the experts..but for beginners..which is 80 -90% of the people on Glazy and if they don't explain it ...it is extremely confusing.

[@YAYKUTTEL]

@John Britt I for one thing have never heard about limits. I think starting on Stull is good, but i agree there isnt a whole lot of other resources that teach it that way. Ive been kicking around writing a book on my stull experiences at cone 10R but, i am but a lowly undergrad. Especially when i feel like i learn something new every firing. Thats anith aspect i wholly agree with; the most important thing about glazing is the process, specific gravity, firing cycle, thickness, flocculation (this has been the big part of glaze development for me)

[@johnbrittpottery]

@@YAYKUTTEL yes, you got it! Chemistry is one thing! Then mixing, choice of materials is next,as you never get oxides in real life. So sieving, ball milling, floc and defloc, sp.gr., etc. Then application and that involves bisque firing. One two or three coats, sprayed, dipped or brushed? Flocc. deflocc, etc Then there is firing and cooling, soaking. reduction, salt, soad, wood, Saggars etc. Then you have refiring, acid baths, decals etc. VERY COMPLICATED! Anyone who claims to know everything and excludes other information is cheating you.

[@juliepeel1794]

How are the limits arrived at? What are the criteria? Do the different limits have different applications or are they just matters of opinion?

[@johnbrittpottery]

Yes...you may have to read some of the papers I listed. John Hesselberth has a history of limits.

[@johnbrittpottery]

miles. Birkett owns Hyperglaze a glaze software, and he has about 30 limits for various glazes. Like shinos. Kaki, etc

[@juliepeel1794]

@@johnbrittpottery Thanks for taking the time John, I'll take a look

[@johnbrittpottery]

Co.plicated...hard to explain in this little box...thought I explained in videos...but maybe not.

[@pietermostert4593]

Some time ago I wrote an article on the Glazy wiki about understanding the Stull chart, which I hope covers some of your criticisms of how it's used in Glazy: wiki.glazy.org/t/understanding-the-stull-chart/857 I'd be interested to hear what you think. I've tried to keep things relatively simple, so someone who doesn't understand the UMF can understand it. My plan is to add another article that looks at silica-alumina charts for a selection of flux bases, to give an idea of the sort of variations in the chart that can occur.

[@johnbrittpottery]

Just saw it thanks. I think I saw an earlier version. It it good. Nice job! I have the same problem you are addressing ...someone who doesn't know UMF and seeing the stull chart without description. Not sure why they don't put in the top loop ...probably too much like a limit !;-)

[@johnbrittpottery]

Not sure why your comment didn't come to me...just happened to see it. If I don't respond, I am not ignoring you , maybe can't see it.

[@pietermostert4593]

@@johnbrittpottery I guess unless someone recreates Stull's experiment with a larger range of values, we won't know where the top loop is. I'd be interested to see what it actually looks like. I've drawn it rounded, but some of the fusion diagrams in de Montmollin's book are quite pointy.

[@pietermostert4593]

@@johnbrittpottery Don't worry, I also only got a notification about your comment when I logged into youtube. There's probably a setting somewhere you need to change.

[@johnbrittpottery]

@@pietermostert4593 I will draw what I have in another video...like a U shape.