Yeah, i think that makes sense. The little bubbles will get pinned to the outside surface, and shaking them can disturb them enough to get them to let go (just like bubbles on the side of a glass of sparkling water ( water “with gas” for those in Europe). If you dont bang those loose, when you apply pressure some (a lot?) of the bubbles will just get pushed into the pores, causing problems just like that air was never pulled out of the pores. Letting the system sit under pressure would reduce those clinging bubbles ... but banging on them is faster Great observation/ idea - i would not have thought of that!