The Effect of Carbon Black Concentration and Ink Viscosity on the Performance of Water-Based Inks

Water based inks containing the same vehicle system have been studied to determine the effect of changing carbon black concentration and/or viscosity within those ranges normally encountered on flexographic newspaper presses. Inks containing 13-17 percent by weight carbon black with viscosity in the range of 8 to 14 seconds as determined with No. 3 shell cup Viscometer were printed on a Windmoeller and Hoelscher Journalflex press at the Providence Journal, Providence, Rhode Island. Proofs were evaluated for print density, cleanliness of halftones, smoothness of solids, contrast, and wet or dry rub resistance. Inks containing 13-17 percent by weight carbon black with viscosity in the range of 8 to 14 seconds as determined with No. 3 shell cup Viscometer were printed on a Windmoeller and Hoelscher Journalflex press at the Providence Journal, Providence, Rhode Island. Proofs were evaluated for print density, cleanliness of halftones, smoothness of solids, contrast, and wet or dry rub resistance. The results of these evaluations indicate that increasing carbon black concentrations and/or increasing viscosity generally increased print density contrast and smoothness of print but produced less clean halftones and, in some cases, poorer rub resistance.