I want to say THANK YOU! THANK YOU! for writing this book. It is exactly what I was looking for! I studied at a 4 year institutions--7 semesters in the ceramics department and I was taught how to calculate glazes with the empirical formula but that was it--no expansion stuff, etc. I wanted more than anything to have a knowledge base to create safe glazes, resolve problems like crazing, and the list goes on. In reviewing parts of your book many of my questions have already been answered. I absolutely love the way you address crazing--and yes, I did try many of the suggestions that were in that CM article and they didn't work. Now I know why. I have a lot to learn but am elated with what I have learned so far.
I've got Insight, I'm doing it right. I'm boiling the water, and shuffling the ice. I'm telling my glazes, "behave and be nice!" Don't craze, don't crack, don't mark, don't make me go back and recalculate! Three minutes boiling, Three minutes ice. They're still acting real nice. Three minutes boiling, Three minutes ice, Wow, still acting nice. Third time boiling, Third time with ice. I did it, they still look nice. Get out the Dazor, look at them real close, Put them almost right up to my nose. I tested them, I did what I could. I tried to make them craze, but they never would. I tested my glazes, I did it just right, I tested for cracks, crazes and marks. I did it all with Insight!!
Despite my having told them about Insight, they still mix up large batches of "baby-poop" glazes that craze.
My glaze is a lithium and strontium glaze and I substituted boraq 2 for gerstely. I first substituted it 1 to1, and the glaze came out too shiny. I reduced the boraq2 by about 10% and it came out almost perfectly, now a little on the dry side. I think 7% will be perfect. For white, I use zircopax. Interestingly, with boraq2 it comes out slightly whiter. For black, I use mason stain 6650 (Cobalt free) and the color is exact. This week I will test my other colors. For me, the texture of the glaze is very important. Almost all of my work is lustred, and I find that the texture in my gerstley glaze helps the metals to adhere better. I suppose it is similar to paving a street-- roughing up the surface before laying the asphalt. The boraq2 has the same surface as the gerstely. Again, Thanks for you help. I just tested for crazing--so far so good. I think you have created my gerstley substitute.
Food safety of our product has suddenly come to our attention. The biggest health problem I think we have is crazing (maybe some leaching). We need a way to solve this yesterday.
I have been using Insight to get smooth, matt glazes without crazing on various sculpture clays for cone 10, 6 and 03. I also use Insight to substitute Canadian materials for the English ones in my glaze recipes. Insight seems to be a robust program and I am glad that I chose this one. But I still am leaning how to use it fully. Also, I find the educational section of your website informative and it is very generous of you to share your expertise with the the rest of us. Thank you so much for your kind assistance.
I just opened the kiln this morning and for the first time in my 30+ years. Total silence. There was not even one ping of crazing. It is said that some time the most monumental events go by in a whisper, but this one needs a shout: THANK YOU, Tony Hansen and all your team at Digitalfire for your persistent vision to put a technically valuable glaze chemistry tool, INSIGHT, in the hands of potters.
Your Magic of fire was a waker upper, had to read it a few times this past few months just to give my head a shake. Yes, I am having crazing issues, and its past time to get away from Gerstly Borate. Just purchased numerous frits and actual commercial stains. After 30 years in the biz, I am going to do this!
I've been reading your entire book on the Glaze Dragon - I'm only at page 77 but I feel much more knowlegeable about glazes and I can't wait until I gained the experience from making and firing glazes so I will have the ability to nail down the mechanism of a glaze effect and bring those mechanisms at will into any glaze I make... I will stick to one glaze or two that I can adjust rather driving myself crazy with hundreds of glazes...
The current problems that prompted me to look for software are not exotic. Cornwall stone is $84 USD, G-200 is $14, so how much of what can we substitute to convert our favorite matt blue ^10 glaze? Why do some glazes craze sometimes and not others? Besides that I find the chemistry fascinating. We have recipes that work very well. I'd like to understand why. The math I find tedious; I did similar analysis for a course on ruminant nutrition, solving for protein, energy, calcium and potassium. Insight will allow me to explore the chemistry without spending so much time on the calculations.
The software installed great. I bought it specifically due to a crazing issue and to help with the fear of understanding glaze chemistry more fully. The video tutorials are useful. Insight as an invaluable tool to this quest of course, sort of a working course that goes at the users pace but which allows them to create their own recipes and truly understanding the chemistry behind them.
My partner in crime (wife) is concerned about crazing and we are both concerned about leaching of toxins into someone's dinner...... so we have a keen interest in stability.
So far your site has been a blessing in that I don't feel I have to go anywhere else to get my information, you have it all (at least as far as I can see now) right here in one place. I am new to glaze formulation but not to ceramics. Recently I have had a crazing problem with a certain clay body I am using and as of today I feel confident I can solve it using information on your website. It is I who want to thank you for making such a clear and concise information depository that can be used by all, especially those new to glaze chemistry.
I have just recently been contacted by a customer due to small lines in her bowl. I am now terrified residual crazing could be happening to lots of functional pieces I have sold! Nightmare! I have a terrible feeling in my stomach. Could anyone tell me if it is the glaze and if there is anything I can do to alter the recipe?
Go look at Tony Hansens page and look at Insite. Incredible amounts of information. He has a great explanation of .. Shivering ---and the opposite----- Crazing. Cause and solution.
I am pulling 8 more tests out of the school kilns next week and will then start downloading images. The program has completely revamped our glazes. Every single glaze has been run through Digitalfire and I have only had 2 or 3 that were not successful. I have fixed crazing, changed feldspars, and downsized the chemicals we will be using, saving the college thousands of dollars. The head of our department is finally starting to see the light! He is finally on board! I have been working on the new glazes since last October and finally I can see great progress and nearing the end of huge task! Can't thank you enough!
I have used Insight for the last 4 years. Love it. Great usefulness in comparing one glaze formula to another in terms of Coefficient of expansion for crazing and shivering analysis.