Trimming is a term for shaving clay at the base of a piece. Trimming works
best when the clay is leather hard. Trimming finishes the shape of the piece as
well as finishes the base to the correct thickness.
Here is how to do it:
Turn the piece to be trimming over. Be careful not to set it down too hard
and dent the top.
Spin the wheel slowly to make sure the piece is centered. If not, adjust
accordingly.
Place balls of clay around the top of the piece (the part connected to the
wheel) to hold it in place while you trim.
If the piece has a handle or something that obstructs your ability to flip
the pot over, use a post to elevate the piece from the inside.
With the wheel spinning, draw two lines with the needle tool as to where the
inside and outside of the foot will be.
Trim the inside of the base and outside of the foot to an appropriate
thickness.
A piece with too thick a base will feel heavy and odd to hold. Too thin of a
base will be too weak, and crack in the firing.
A good thickness is approximately 1/8 of an inch thick.
To measure thickness, tap gently on the base of the pot. If it is a light
sound, the base is thin and halt trimming. If the tap feels like you are hitting
a lot of clay, keep going.
Use a sponge and your finger to smooth the area that was trimmed.
Gently remove the pot from the wheel, making sure not to damage the top, and
place it to dry until bone dry to fire it.