Several studies have been published on Ink Jet Computer-To-Plate. Some authors described a “Mask approach”, where they jet a fluid that block UV radiation on a conventional photopolymer plate, and further UV expose and process the plate. Some recent studies described “Direct imaging” on the plate substrate. The main concern for direct imaging is to control resolution by limiting spreading of the droplets (poor wetting) whereas obtaining excellent adhesion of the image to get high press run-length during printing. A way to partially achieve both requirements could be to jet a hot melt fluid onto the plate substrate directly: spreading is controlled by fluid phase-change. The drawbacks are a 10 to 20 times thicker image than on a conventional plate and low press run-length because of poor resistance properties of the wax-based fluid. In this study, a cationic copolymer (resp. anionic), partially neutralized by formic acid (resp. amonia) is solubilized in water and jetted through a piezo Ink Jet printer on a basic (resp. acidic) plate substrate. Water is evaporated and the copolymer forms the image area of the printing plate. The purpose of this paper is to show how to reconcile good image resolution (or “poor wetting”) and long press run-length (or “good adhesion”) by an Acid-Base interfacial matching approach.