Brief Introduction to the Role of pH Meters for Paper Acidity-Alkalinity Monitoring
pH meters and conductivity meters are commonly applied in the printing industry. Proper application helps reduce printing costs. Therefore, printing enterprises shall actively use pH meters and conductivity meters to reasonably control the pH values of paper and fountain solution before printing. This practice can not only improve printing quality, but also cut consumable consumption and lower costs.
The ink-water balance, ink drying performance and ink layer quality are critical during printing. Hence, industrial pH meters are used to monitor the acidity and alkalinity of paper, so as to avoid excessively low paper pH which would inhibit the oxidative polymerization and drying rate of printing ink. The printing industry adopts pH meters to control paper acidity and alkalinity as much as possible and improve printing quality.
What adverse effects will be caused if paper is too alkaline? Excessively alkaline paper may alter the acidity of fountain solution and weaken the acidity of the hydrophilic gel layer on the non-image areas of the printing plate. The decline in hydrophilicity of non-image areas will trigger ink-water imbalance, reduced ink tinting strength, dull printed graphics, plate scumming and plate blinding. It can be seen that controlling paper pH is of great significance in the printing industry, and pH meters serve as an excellent auxiliary tool.
In addition to monitoring paper acidity and alkalinity with pH meters, pH meters and conductivity meters are also used to detect and control relevant parameters of fountain solution. Overly acidic fountain solution will corrode and damage the blank areas of printing plates and cause plate scumming. Overly alkaline fountain solution will corrode ink and paper. Therefore, the acidity and alkalinity of fountain solution must be strictly controlled, with special attention paid to the pH value of buffers in fountain solution. Besides, water hardness and temperature shall be well controlled to prevent water from affecting the pH of fountain solution. The conductivity of fountain solution also exerts a considerable influence on its pH value.
