Operation Digital Output

Q. What plate characteristics chiefly affect package printing?

A. At least three. First, exposure speed and resolution. The photopolymer emulsion on ordinary conventional plates is a single coating that varies in thickness. As a result, single-coated plates are relatively slow to expose. That loses precious time in prep. Single-coat plate resolution is also low, due to lack of definition in "dot" images. Dual-coated plates have thicker emulsions that expose faster and have a higher profile and dot definition. Next is a plate's ink and water balance. How much water a plate requires is determined by the graining of its aluminum base. Most conventional plates are electrochemically grained. These need more water than plates that are brush-grained. Water affects a job's color consistency, drying, coating and turnaround. Excess water leads to ink emulsification, dilution and toning. So, the less water a plate needs, the better (or faster) these become. A plate that requires minimum water and prints at highest image resolution ensures top image quality and color consistency. It also saves drying time and permits faster delivery. Finally, there is durability. A plate image formed in a heavier, dual photopolymer emulsion coating will run longer than the same image in a thin, single-coat emulsion.