Analysis of alcohol-free printing

Alcohol-free printing using alcohol substitutes is more likely to achieve ink-water balance. Printing with a specific thickness of ink film that has not been diluted with alcohol can result in higher-quality prints with fine dots and less emulsification.

Alcohol replacements differ from IPA (isopropyl alcohol) in several key properties, including their viscosity, surface tension, pH, and conductivity of the fountain solution. Non-alcoholic products cannot be freely applied to different printing presses. This requires close communication with the printing operators and seeks the best fountain solution formulation from suppliers.

Adding IPA to the fountain solution greatly increases its viscosity, but many alcohol substitutes have little or no effect on viscosity. Due to the lower viscosity of alcohol substitutes, less fountain solution is measured by extrusion or using a measuring roll on a continuous contact dampening roller. This necessitates an increase in the dampening roller speed, causing many printing operators to mistakenly determine More water must be used when printing with an alcohol substitute fountain solution. In fact, the solution to increase the viscosity to a certain extent is to cool the fountain solution.

The ability to wet the plate quickly and form a thin film of water is the two key requirements for offset printing on the fountain solution, which is primarily determined by the surface tension of the fountain solution. It is generally believed that the dampening fluid with low surface tension can be used in high-speed printing, but there is also the opposite report in Europe. It is understood that current alcohol alternatives can achieve the low surface tension of IPAs that print operators are accustomed to.

The surface tension of pure water is 72×10-3 N/m. In the fountain solution, the alcohol concentration is 10%-25%, and the surface tension is reduced to (35-45)×10-3 N/m. The fountain solution can quickly form a continuous film covering the entire printing plate. Alcohol-free fountain solutions use surfactants and solvents to reduce surface tension.