Saturday, July 14, 2012

Up From Underneath - 91398B

Up From Underneath - 91398B 

The slow cooling factor of these platters was a direct result of the way they were fired. Imagine the inside of most kilns... a big giant empty chamber surrounded by bricks.... all the fire surrounding the ware on thick shelves. When fired this way, these platters would crack right down the center as they were heating due to the massive thermal shock (the difference between the temperature of the edge of the platter vs the center of the platter). If they were heated too fast, CRACK! Since there are no real windows in kilns, you couldn't tell which platters had cracked, and which had spilled their glaze contents all over the shelves. For the first few months of making these, the loss rates were almost 90%. The cleanup mess was insane. 

To slow down the extreme heat, I decided to create a "muffle" for the ware. By building a baffle of bricks that surrounded the platters, the flame had to heat up the bricks (huge and heavy) before they could begin heating the platters. The upside to this was that cracking dropped dramatically. Unfortunately, by adding all of this excess brick, the firing times increased enormously. From a typical twelve hour cooling time (after a 9 hour firing)... my firing times jumped to 16 hours of firing and over 24 hours of cooling. Within a few months, my firing times extended into days instead of hours. Cooling times extended sometimes for three or more days. 

One of the effects of this radically slow cooling was that the fluid glazes had ample time to recrystallize and form fascinating geological formations. Some of these crystals were so spectacular. Other times, the glazes made the most simple, almost boring, flat shields of matte crystal formations. In this platter, you can see the crystal patterns formed over a fluid glaze underneath. What I initially hoped for is almost impossible to describe. I wanted snowflakes of peach floating on a blue watery field. Due to the extended cooling time, the titanium that was seeding the glaze solution spread and formed thick icy sheets of titania crystals. Looking back at this platter, I wish I had been able to experiment more with this style of glaze. So many opportunities, right under the skin.

More glaze experiments at Glaze Tectonics!

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