The harm of ink and ink imbalance in offset printing

Offset printing is based on the principle of incompatibility of water and ink. If the water content is too small, it will inevitably result in an increase in the density of the field. The image area will increase in area or deform. In severe cases, a paste plate will be produced, and the area will become dirty easily and blur the imprinting level. , causing waste products.

Excessive moisture, under the effect of mechanical pressure, can easily cause ink emulsification, reduce cohesion and water resistance. The greater the moisture, the longer the time, the more severe the emulsification, and the more severe the printability of the ink. Thus, the ink accumulates on the ink roller and the printing plate, and cannot be normally conveyed, forcing the printing work to be interrupted, and the water roller must be washed again and replaced with a new ink. As the ink emulsification, but also cause the ink to fade, sharp decline in saturation, viscosity and adhesion weakened, so that the image text points deformation, pricking, not smooth, resulting in paste version and other phenomena. In particular, after the dot overlaps, the ink layer is light and dull, the level is unclear, and a large color shift failure occurs.

If the moisture is too large, the printed paper will be stretched due to the absorption of excess moisture. During storage, the paper will naturally release moisture on all four sides, resulting in irregular expansion and contraction, resulting in inaccurate or incapable overprint of the printed product.

Excessive moisture will also affect the extent of blotting to varying degrees. The ink is dried by the penetration of the binder and the volatile conjunctiva. When it contains a large amount of moisture, the penetration is difficult, and the time for volatilizing the conjunctiva is also prolonged. Sometimes it is even difficult to dry, which affects the continuous overprinting, and it also easily causes the backside of the printed product to become dirty.

The offset of water and ink in offset printing is balanced by various variable factors in the mechanical movement and printing process. Therefore, there are many factors that affect the balance of water and ink, but also more complex, but there are rules to follow. The general principle is: "Water and ink go."

Reprinted from: "Print Media"