Sunday, February 22, 2009

Testing, Throwing, Painting

I've spent the past few days throwing a few cups in order to test my liner glazes. If you're interested in 'how' to test your funtional ware for stability, I would suggest going over to Clayart's forum or for the detailed how-to's. I have completed the 'freezing/plunging in boiling water' method and so-far-so-good - no crazing!

A word of caution - Be careful when doing any type of 'shock' testing on your ware. Any number of things can happen i.e. popping, shivering (when sharp slivers of glazes literally fall off the clay-body), exploding, or whatever.

Because I consider myself a novice in ceramics, and most certainly a novice in the science of glazing, I don't think I should go into 'details' of how I tested. I would not want, in any way, to be responsible for someone's misinterpretation of my testing procedure (yeah, that's right, I'm chicken - Wuh Oh, this is sounding like the subject of my last post!). Instead, I would encourage anyone interested in the subject to go to the above sites. You can get enough info from the forum on how to test. And if you need more info, you can always join their listserve and ask for help. Ron Roy is a regular contributor to Clayart's listserve and I see John H.'s posts on there often also. A lot of times potters will specifically ask for Ron or John's help on a technical problem they're having. These 2 guys, as well as the entire listserve community are a sea of information. Have to admit, I quit subscribing to the listserve a few years ago, because I didn't like getting so many e-mails from them, even if only weekly. Once I got the e-mail I felt obligated, or just too curious, to run through it to see if there was anything I may be interested in - one more thing (like the WWW) to get side-tracked by. For me, it is much more convenient to go there for any particular subject I'm interested in. Saves time and uneccessary e-mails/reading. I go to that site for anything and everything concerning a problem/question I may have regarding ceramics.

Also, the potters there mention how the American Society for Testing and Materials ASTM (ASTM C 554-93) suggests testing for thermal shock, which will be my next step. I could not find on their site exactly where they explain the procedure on how to perform this test, but was able to pick up enough info in my Mastering Cone 6 book AND at to do the test; but I'll perform that test using cups, not test tiles. It involves heating the ware in the oven to a certain degree, then quenching in room temp. water, which is a more rigorous test than the first (again, be sure you research how to do this test before actually doing it and proceed with caution!).

And alas, on painting, just playing around with a mini watercolor (4.5" x 5") of a fallen oak leaf. I really want to get back to painting. Gotta make the time...


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