Monday, September 26, 2011

Making Ceramic Pottery: Trimming


Trimming excess clay off the bottom of a pot not only makes the pot lighter in weight but also refines the shape and adds interest to the pot. A footring (or foot) is a raised circle of clay at the base of a thrown pot on which the pot will stand and is a typical end product of trimming. Sometimes trimming a foot can actually take longer than throwing the pot!

To trim a foot you must wait until the pot has air dried a bit to the leatherhard stage (clay is no longer malleable, but will crack or distort if pressure is applied). Trying to trim a foot onto a pot that has just been throw will end in utter disaster since the pot will collapse under its own wet weight. 

Trimming: this is a plate that's been turned upside down so that I can trim and add a foot to the bottom.
The device with the black tabs is an ingenious device called a Giffin Grip, best purchase ever! It snaps onto the wheel head and the tabs slide in to center and hug the piece so it can be trimmed.  The old school way uses wads of clay to hold the pot in place, and they never stay!!
Trimmed plate with a foot. In addition to adding the foot, I've also rounded out the bottom of the plate to remove extra clay and make it more pleasing to the eye.
These are the tools used to trim - as you lean the sharpened metal edge of the trimming tool against the clay (while the wheel is spinning) ribbons of unwanted clay are removed from the pot. The flat metal tool is pressed against the clay to produce a smooth surface.

Next time: Glazing. How those pots become colorful.

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