From the outside this seems like a fairly pointless exercise. “I’m about to spend a whole bunch of time working on a lump of clay before I do an real work on the lump of clay? What’s that all about?”  I hear you cry…

If you are working clay directly out of the bag, it probably is largely pointless. It’s easier to see the point when you aren’t using dress clay and have to mix several different bits of clay all with different moisture levels.  Air bubbles are also a concern…  But there is a secondary purpose to wedging that may or may not be apocryphal, but in my early experimentation seems to bear out.  

The analogy for me is softening butter for pastry work. If you make croissants, after you make the bread dough, you have to insert the butter that is cold, but workable. If you don’t, the butter either melts into the dough and you simply end up with bread, or the butter is too hard and it rips the dough and unpredictable things happen. The best way I have found to prepare the butter is basically to hit it with a stick. If you beat up the butter, what you end up doing is fracturing the structure of the water and fat in such a way that the bits of butter slide past each other and the butter will fold nicely. It seems that something similar goes on with the clay. If you wedge it properly,  basically kneading it, you force any incidental bindings between the bits of clay to break up.  Given that clay particles are apparently platelike, orderly kneading and twisting of the clay will arrange those plates in a regular grain. That this may or may not help with throwing is something that I cannot personally attest to, but it is the popular opinion. If someone has a handy electron microscope, maybe we can find this out…