Friday, February 26, 2010

fail and pass

Yesterday I walked into my studio to find Bethanie, the kiln, flashing “FAIL” on her control panel. Not a good way to start the day especially since the kiln was filled with orders that were in their glaze firing. The pieces did not reach the necessary high temperature, and look all shriveled up and color-less.

Bethanie’s “fail” message pretty much summed up the day to follow: I had another failure casting the large boat vases I have been working on for months. Huge cracks formed on the sides, as the porcelain was not shrinking off the mold evenly. Sigh. That was my fourth attempt. Coincidentally, a potter from Austen, TX wrote me asking for my advice on her plate molds. Her pieces were forming huge cracks as they dried in the molds, too. Needless to say, I did not have a solution for her, but wait, maybe I do now...

Today I walked into my studio to find the vases dried off the mold perfectly! Tears of relief welled up as I popped open the molds. Here is the result, next to it’s wooden original. Whew.

How did I finally achieve this, you are asking? Simply by dusting the mold with a light coating of Nepheline Syenite (no, it’s not something you find on the ingredient list of Twinkies, but a genuine mineral). This trick was suggested by my former professor at RISD, Larry Bush, so I can’t take the credit. My somewhat uneducated guess is that the fine particles of Neph Sy allow the porcelain to slide along unhindered as it dries and shrinks in the mold. Oh happy day.

As for Bethanie’s “fail” message, once I stopped hyperventilating, I looked it up in the manual. It meant that I needed to replace the thermocouple. All that drama for a simple fix. If any Skutt Kiln techs read this, please consider programming something like “time to change that pesky thermocouple, don’t panic” instead of “FAIL” into the control panel. Gentler wording might prevent a heart attack... just puttin’ it out there.