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Summary:
Many laboratory methods involve pure ink and dry surfaces, but actual presses require that we understand the interaction of emulsified inks with dry and wetted coating surfaces. In a previous paper, we found that on coated papers ink tack buildup of emulsified ink is faster than the pure ink and pre-wetted surface by fountain solution sets ink faster than the dry surface. Here, the effect of ink emulsification on gloss dynamics on plastic film, clay-based coated papers, and a series of well-characterized model coatings varying in pore volume, pore size, and binder type is examined. A novel glossmeter is used to measure the dynamics of the ink gloss right after printing. Emulsified inks differing in fountain solution content from 1% to 30% are prepared in laboratory. ESEM (Environmental Scanning Electron Microscope) is used to examine the microstructure of emulsified inks, which is found to be a more useful way to view the real droplet size of the emulsion compared with the conventional method with optical microscope. In the initial stages ink emulsification enhances the film leveling. In the final stages, ink setting increases for emulsified ink and final gloss decreases. The leveling speed of the ink film depends on the content of fountain solution and coating properties. Increasing the content of fountain solution increases the leveling of ink film. Finer pore coating sets ink faster and can reduce the difference between pure ink and emulsified ink in film leveling. The gloss is lower on pre-wetted surfaces than dry surfaces for both pure ink and emulsified ink. Ink films level faster on the coated paper than on the plastic film even when ink penetration into paper can slow down the leveling.