Once the pot is centered, it must be secured to the bat or wheel. This can be accomplished in several ways. For some very practiced potters, they are able to hold the pot in position using a finger on the top (erstwhile bottom) of the upside-down pot. For potters who do not do a lot of trimming, this may not work.
One of the most common methods of securing the pot is to hold it in the centered position with one hand. With the other, place a wad of clay up against the pot and smear downward (with no pressure going inward against the pot itself) to attach the damp clay to the bat. Rotate the wheel one quarter turn and repeat, still holding the pot in place. Place and attach the second clay wad. Repeat for the third and fourth wads of clay.
Another possibility is to center a pad of clay on the bat, prior to trimming. Use a metal rib to remove all excess moisture before re-centering the upside-down pot on it for trimming. Once the pot is centered, gently press the pot down into the clay pad slightly.
Difficult shapes such as wide bowls and platters, or vases with long necks are usually best trimmed using a clay or bisque chuck. To make a chuck, throw an opened cylinder of clay, wide enough to match the inner floor for a wide form, or just wide and tall enough to support the shoulder of a thin-necked vase. Remove all excess moisture from the chuck, inside and out. Place the on or into the chuck and press down slightly.
Another option, especially if you do a lot of trimming, is to invest in a tool such as the Giffin Grip. This tool self-centers the pot and secures it to the wheel head for trimming.
