Drying is one of the most important processes of printing. During printing, ink must be fluid to be able to transfer to substrate, but it is expected to dry or solidify as soon as possible. Though it is very difficult to realize such a quick change from a fluid state to a solid state, various means have been developed. In this article, we explain the state of the art of drying, including inks, substrate and drying equipments for major printing processes, sheet-fed offset, web offset and packaging gravure printings.

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The dynamic surface tension of fountain solution is essentially important in discussing surface chemical interactions between ink and fountain solution during lithographic printing process since the fountain solution in general contains some surfactants that can be expected to exhibit the time dependence of the surface tension. In actual printing process, the fountain solution surface is subjected to continuous deformation on dampening rollers and printing plate as well as at the printing nips. This paper describes the dynamic surface tension of a model fountain solution including dodecyl pentaethylene glycol C₁₂H₂₅O (CH₂CH₂O)₅H (C₁₂E₅) as a surfactant and the new method of the dynamic surface tension measurement by the steady surface deformation. By this method derived from the maximum bubble pressure method, a single air bubble formed on the tip turned upward in test liquid can expand stationarily until the detachment from the tip occurs. The empirical relationship between the detached bubble volume and the expanding (or growing) time (e. g., several to a few hundred sec.) obtained for some pure liquids and aqueous solutions was found to be very similar to that between the drop weight (or volume) and the dropping time obtained by the drop weight method. The analytical treatment of the experimental data due to this analogy can lead to the derivation of the dynamic surface tension of C₁₂E₅ surfactant solution as well as that of static surface tension of testing liquids free from surfactant. Evaluation from some adsorption equations for surface deformation shows that the dynamic surface tension obeys diffusion-controlled adsorption kinetics as expected. Also diffusion coefficient thereby obtained in the vicinity of 5×10^-6cm²/sec confirms that the experimental results are reasonable.

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We investigated the possibility of application to the screenless lithography of positive working presensitized plate using sub layer treated with super absorbent which absorbed alkaline solution, and determined the relationship of surface roughness to continuous tone reproduction and the most suitable production condition. As the results, the PS plate having this type of sub layer particularly one with large surface roughness gave a good reproduction of continuous tone.

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The Japanese Industrial Standard Z·8102 specifies specially the names of surface colors. They can be divided as follws: (1) Systematic Names and (2) Conventional Names. Further, the former can be divided into (a) Basic Chromatic Colours (red, green, violet, etc.) and (b) Basic Achromatic Colours (white, gray, black). Three types of Modifiers, which are (1) vivid, deep, pale, etc., (2) light, dark, (3) reddish, greenish, etc., can be used for the names of basic colors. Tuus, names can be expressed as “vivid yellowish green” or “light purplish gray”. 168 Conventional Names (pink, olive, peacock blue, etc.) are standardized for cases when the systematic names are difficult to use.

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