SteveC, a lip on the inside and outside of the spinning bowl at the top to stop the migration of the heavier particles of gunk.
Look at the drawing at the beginning of the thread. It shows a shaded area in the bowl under lip that represents the oil (my take on the drawing) this lip prevents the gunk from leaving the bowl, but allows the oil (lighter than the gunk) to flow out.
I do not understand the physics of it but the heavier particles are trapped under the lip and then cleaned out.
Edited by Lu47Dan (03/19/11 05:21 AM)
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