This method allows you to uniformly wedge very large pieces of clay for large pots.You also can add water (or softer clay) to pieces of clay that have become too stiff, or even mix. 3 sept. 2014 · Wedge definition, a piece of hard material with two principal faces meeting in a sharply acute angle, for raising, holding, or splitting objects by applying a pounding or driving force, as from a hammer.