Making Ceramic Pottery: Trimming

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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Making Ceramic Pottery: Throwing on the Wheel

Wheel Throwing

 

My preferred technique for making pottery is throwing on the wheel. Throwing  is the term used to describe how the rotating wheel ‘throws’ the clay outwards while the potter uses their hands to control and mold the clay against this force.  Keeping the clay in the center of the wheel (centering) may appear effortless, but it is a skill that takes great patience and lots of practice! 

Throwing a ceramic piece on the wheel starts out with centering of the clay. Repeatedly bringing the spinning clay up into a cone and pushing it back down until the lump of clay spins evenly and without any wobble (indicating it's off center). Water is used to lubricate the clay so that it spins smoothly in your hands.

 

Opening up: a process of pushing down in the middle of the centered clay and pulling out, creating a mouth

Pulling up: repeatedly pulling up on the clay while the wheel in spinning; the wall of the cylinder gets thinner as the vessel gets taller as you can see in the following pictures

And now to finish the piece - the desired shape is formed, edges and walls smoothed out.

Finishing: in this case I have narrowed the opening of the cylinder to create a small, narrow opening, like you might see on a jug or a luminary (which is what this will be). Here I'm using a wooden tool called a rib to push against the clay and smooth its surface.

Once I’m satisfied with the vessel I’ve created, I can either cut it off by sliding a fine wire between the bottom of the pot and the wheel head, remove it from the wheel and leave it to dry completely, or trim the bottom to create a footring (or foot). A foot is a raised circle of clay at the base of a throw pot on which the pot will stand.

Here are examples of freshly thrown pieces. Here you can see some ring holders, plates, and a small bowl (cylinder). The plates are sitting on ‘bats’. A bat is a piece of pressboard that can be taken on and off the wheel head allowing you to move the piece without cutting it off.

Before the pieces I've thrown can be trimmed they must firm up a bit by drying to what's called the 'leatherhard' stage. At this point the clay can still be marred if you push your fingernail into it but it's not so soft that you can distort the shape with the push of a finger. 

Next time I will show you how to trim a foot.