Materials for Black & White Printing

The printing material is a paper or other base with a light-sensitive coating. Until comparatively recently, the base for black-and-white material was always a particularly pure form of paper coated with barium sulphate and other additives called baryta paper. Its disadvantage is that paper is a highly absorbent material needing a large volume of water to wash it free of the chemical solutions in which it is immersed during processing. The Resin coated versus fibre based papers solution was to coat both sides of the paper with a plastic sheet before laying down the emulsion. The solutions penetrate only the thin emulsion layer and are washed out with comparative ease. The advantage of RC material is too important to be dismissed lightly. The complete absence of an absorbent base is a tremendous step forward, totally eliminating the hazard of incomplete washing because of chemicals trapped in the material fibers. The consequent reduced washing times and rapid drying is at least a useful bonus. There are disadvantages for the small darkroom. The material tends to float on the surface of solutions and needs to be pressed down occasionally. That has to be done with care because the surface is fragile and easily damaged when wet. The special ink is required to mark the back of prints. The material is sensitive to direct heat, which can melt the coating.