Sunday, July 31, 2011

The Joy of Metal Clay: A word about firing & my current project

Firing the project that I am currently working on reminded me of some important firing tips. If you remember from last week I am making a pendant made up of two domed squares. I fired this piece (in haste, it was a long day so I wasn't thinking as clearly as I usually).

I placed it in the kiln not really thinking about the best way to support it. I just placed it on a bed of vermiculite and turned on my kiln. This is the result:



The domed pieces collapsed together!





I forgot one of the key instructions I give my students: Think about how GRAVITY will work on you piece!!!! What I mean in this statement is to look at you piece and think about supporting it so that when it is heated that the molecules are sintering it doesn't collapse. I find this hard to explain in writing. But let me try.




For the piece in question the problem is that when it is placed flat in the kiln even though there is some vermiculite on the one side the gravity will still pull and flatten it. If I have placed it upright, as it illustrated below the force of gravity is pulling down on it and the domes don't flatten.


More simply if you think about a simple one sided domed piece. If you put on the shelf with the edjes of the dome on the kiln shelf (think like a turtle) the shelf with act with friction and stop it from collapsing. If you put it the shelf with the edges upward (like a turtle on his back) gravity will pull and it will flatten slightly.










When things go wrong, not all is lost. After yor piece is fired and before you polish it you can often try and shape it back. For the piece in question, I slid a pair of scissors into the edges and rotated them to spread apart the flattened edges. Voila!


















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