Has anyone seen this gadget, SIFDIS:
They claim that no tapping of the basket is necessary. They argue it will separate the contact from portafilter body. Simply sieve then tamp.
I can understand that the sieving will eliminate absolutely all clumping (like sieving flour in baking) and the water should have an even pathway after tamping. Whereas a clump may not break up after a tamp and not allow the water to distribute through the bed? Is this part of the thinking for WDT?
Another thought regarding distribution - vibration excites the particles and potentially splits them up. When the vibration stops, the particles settle in an evenly distributed fashion. Industry uses this technique for all sorts of things.
That’s my 2 ideas. Feel free to tear these limb from limb.