The relationship between dirty printing plates and ink viscosity

In modern printing technology, controlling the viscosity of ink is crucial for ensuring high-quality and flawless prints. One key factor is to prevent the occurrence of “dirty versions”. This article will explore the causes of dirty plates during the printing process and how to avoid this problem by adjusting the ink viscosity. What is a dirty version? Dirty plate refers to the phenomenon of decreased image quality caused by dot enlargement or plate sticking during the printing process. When the ink viscosity is too low, the ink will overflow from the small dots on the printing plate, causing adjacent non graphic areas to also be colored. This phenomenon is called “dirty plate”. The effect of ink viscosity on the fluidity of dirty plates: The viscosity of ink determines its fluidity. If the ink is too thin (i.e. viscosity is too low), it is easy to diffuse to areas that should not be colored under pressure, resulting in dirty plates. Dot transfer: Appropriate ink viscosity helps achieve good dot transfer effects. Insufficient viscosity may cause excessive dot expansion or inability to fully transfer to the substrate, which can result in visually dirty plate effects. Drying speed: The drying speed of ink is also affected by viscosity. If the ink dries too quickly, it may solidify before it is completely transferred to the paper, which can also lead to dirty plates. How to prevent dirty plates by adjusting ink viscosity? To prevent dirty printing, it is necessary to accurately control the viscosity of the ink based on specific printing conditions and material characteristics used. The following are some common measures: choose the appropriate ink formula: Different types of ink have different initial viscosity and rheological properties, so when selecting ink, it is necessary to consider the expected printing environment and working conditions. Using a viscometer for measurement: Regularly measure the viscosity of ink using a viscometer and make necessary adjustments based on standard values. The commonly used viscosity units include poise and the international standard unit mPa · s. Adding ink conditioner: Depending on the actual viscosity required, ink conditioner can be added appropriately to change the viscosity of the ink. For example, adding a debonding agent can increase the viscosity of ink; Adding a diluent can reduce the viscosity of the ink. But it is important to keep the other properties of the ink unchanged. Monitoring printing temperature: Temperature changes can affect the viscosity of the ink, so it is necessary to maintain a stable printing room temperature and monitor the temperature stability of the ink. Experiment and testing: Before actual production, a series of small-scale experiments should be conducted to determine the optimal ink viscosity range, and this standard should be strictly followed in formal production. Maintaining appropriate ink viscosity is extremely important for preventing dirty printing during the printing process. By selecting and using ink reasonably, combined with effective viscosity management methods, the quality of printed products can be significantly improved, the scrap rate can be reduced, and costs and time can also be saved. As a professional printing practitioner, we should continuously monitor the latest technological developments and optimize our workflow to ensure that every product meets the highest standards.