You rock the plate, not shake it. As the ether and alcohol evaporate during draining of excess collodion, you rock the plate to stop the formation of ridges on the plate. The evaporation of the solvents is constant.... So any hesitation will result in a ridge, or wave in the pour. Pouring a plate is a deliberate and 'by feel' action, keeping the collodion moving and not hesitating, or going back over a covered area, and draining consistently will normally result in a 'clean' pour, with few ridges. The rocking also helps keep the drip edges/corner to not be as thick, and more even with the rest of the plate. Hope that helps?