High Speed Camera Studies of Ink Misting.

We have continued our studies of the behavior of ink in motion on an ink distribution system. This current film is the result of our continuing efforts to investigate the origin of ink mist. Rupture of ink filaments as a source of ink mist has been confirmed, but the studies indicate that the phenomenon is more complex than had been realized. The ridging shown in previous work has been studied further. Attempts to investigate the effect of cavitation and entrapped air on the ink emerging from the nip have been made. There is some evidence that the type of ridging which occurs may influence the behavior of the ink in the nip. A somewhat spongy, porous mass of ink comes out of the nip when the viscosity and rotational speed are high, and this may be responsible for the short, shred-like filaments and irregular shaped particles which we observed. The paper is presented as a moving picture of oil inks running on an Inkometer at normal film thickness and speeds comparable to normal press speeds. The pictures were taken with a Fastax camera at speeds of up to 8,000 frames per second.