Abstract: High photo resolution of over 100 lines is obtained for solder masks of thicknesses greater than 0.002 in. (0.005 cm) with liquid photopolymers of special compositions deposited from mesh screens over printed wiring board traces and photoexposed with a phototool image in contact with the photopolymer. Special interrelated properties of the liquid photopolymer interacting in an explicit process of screen depositing two adjacent liquid polymer layers include freedom from volatiles, a paste-like viscosity permitting use with mesh screens of about 60 mesh to obtain a uniform thickness layer free of bubbles and mesh marks, solder mask insulator and heat resistance characteristics, an ability to photo flash through a phototool image in contact with one layer surface and the other surface exposed to air to polymerize through a significant thickness of about one-third of the layer thickness, photo response to polymerize to a depth of about 0.02 in. (0.