Friday, July 9, 2010

Wedging Clay and Throwing a Slab

At right is a diagram of how i 'throw a slab.' It's similar to wedging the air out of a body of clay, and creates a large smooth slab without the use of any mechanical equipment. For this process, you will need to wedge or throw your clay on a wooden board (appx. 18"x 24")upon which you've stretched some unprimed, raw canvas. If you attempt to do this on a slick surface, the clay will simply stick like pie dough on an unfloured surface and you'll have to scrape it up and start again. Starting with a cube of clay (no more than a pound or two), simply lift it up with one hand to about 12" to 15" above the surface of the board, and throw it straight down, turning each lift so that it maintains a cube shape, to be sure any air bubbles have been driven out. Once you're confident that the clay is sufficiently de-aired, then continue to lift and throw it down, but confine your 'turns' to two sides, and throw the clay down at a slight angle, so that it begins to spread out like a pancake. Don't try to do it too fast or the clay will tear or crack. Every time you pick up the slab to flip it over, grab an adjacent edge, so that the clay is driven out evenly from the cube's original center. It's a lot simpler a motion than i can draw in a single diagram, and it takes practice to get the feel of what's going on. I will try to make a demo video for a later post. Please don't hesitate to email me with any questions or suggestions if this seems unclear. --A footnote: i work with slab-built cones because i HATE to hollow out a solid sculpture, and if you fire a solid chunk of ceramic clay any thicker than about 1" or 2" it's highly likely your piece will explode from the expansion of chemical water trapped in the greenware that turns to steam in the high temperatures of a kiln. Building with slabs is a bit different, but well worth the practice, so Good Luck!!

Next post will document a rabbit head from slab-built cone to finished bust.

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