The Mystery of Ink Viscosity in Different Printing Methods

Date: Jan 29 2025 From: Star Color

In the printing industry, ink serves as the key element that endows printed materials with color and vitality, akin to paint in painting. The viscosity of ink is particularly crucial in determining the printing quality. Different printing methods have unique requirements for ink viscosity. Today, let's uncover the mystery behind ink viscosity in various printing methods.

Gravure Ink: Low Viscosity

Gravure printing is commonly used for printing packaging materials such as plastic films and metal foils. The viscosity of gravure ink is relatively low, typically ranging between 50 - 500 mPa·s.

Gravure printing transfers ink through the engraved cells on the printing cylinder. Low-viscosity ink can quickly and uniformly fill these cells and smoothly transfer from them onto the substrate during printing. If the ink viscosity is too high, it can lead to poor ink transfer, resulting in cylinder clogging, which not only affects printing quality but also significantly reduces production efficiency. Low-viscosity gravure ink functions like an agile messenger, freely navigating the printing process to ensure exquisite and efficient packaging printing.
The Mystery of Ink Viscosity in Different Printing Methods

Flexo Ink: Medium Viscosity

Flexographic printing is widely used in label printing, corrugated box printing, and other fields. The viscosity of flexo ink is medium, with water-based flexo ink typically ranging between 200 - 2000 mPa·s. Solvent-based and UV flexo inks also fall within this range, although specific formulations and applications may vary.

Flexographic printing employs flexible plates, with ink being transferred and metered through anilox rollers. Medium-viscosity ink forms a uniform ink layer on the anilox roller surface, ensuring adequate transfer to the plate without damaging it or compromising transfer efficiency due to excessive viscosity. Moreover, medium viscosity facilitates rapid spreading and drying of ink on the substrate, meeting the high-speed and efficient production requirements of flexographic printing. Flexo ink functions like a balancing master, finding the perfect equilibrium among various factors to ensure a smooth printing process.

Offset Ink: High Viscosity

Offset printing is an extremely common method in the printing industry, widely used for the production of books, magazines, posters, and other printed materials. The viscosity of offset ink is relatively high, typically ranging between 10,000 - 50,000 mPa·s.

Why does offset ink require such high viscosity? This is closely related to the working principle of offset printing. In the offset process, ink passes through the ink fountain, ink rollers, and then transfers from the plate to the blanket before finally being printed onto the paper. High viscosity ensures stable ink transfer between the rollers, preventing issues such as ink splashing and emulsification. Meanwhile, an appropriate high viscosity aids in the rapid fixation of ink on the paper, preventing excessive spreading, which results in printed text and images with sharp edges and high color saturation, thereby enhancing the quality of the printed materials.

Screen Printing Ink: High Viscosity

Screen printing can be performed on various surfaces such as glass, ceramics, and textiles. The viscosity of screen printing ink is high, typically ranging between 10,000 - 100,000 mPa·s or even higher.

Screen printing transfers ink through mesh openings by squeezing with a squeegee. High-viscosity ink, under the action of the squeegee, allows better control over ink flow and transfer, ensuring that ink accurately passes through the mesh to form sharp images and text. If the ink viscosity is too low, excessive ink flow during squeegee movement can lead to uneven edges and reduced resolution in the printed pattern. Furthermore, high viscosity helps maintain a certain ink thickness on the substrate, creating a three-dimensional printing effect. Screen printing ink functions like a three-dimensional sculptor, utilizing high viscosity to endow printed materials with unique texture and dimensionality.

Ink viscosity plays a crucial role in different printing methods. Understanding these characteristics not only helps printing professionals better control printing quality and produce exquisite printed materials but also deepens our understanding of the mysteries behind printing for ordinary readers.