How to Properly Select Paper for Digital Printing?

With the development of on-demand printing, digital printing equipment is becoming increasingly prevalent in production. When digital printing equipment malfunctions, paper is often overlooked, yet it is a critical factor. What kind of paper should be chosen? Specialized digital printing paper or offset printing paper? How should paper performance be considered? How to handle paper storage?

Factors Affecting the Impact of Paper on Digital Printing Quality

1. Moisture Content

Paper with excessively high moisture content has lower surface tensile strength and surface strength, higher plasticity, and the drying speed of impressions is affected, making the back of the paper prone to dirt. Conversely, paper with too low moisture content generates static electricity due to its stiffness during printing, leading to uneven paper feeding and quality issues.

To reduce pre-curling, paper should be stored in moisture-resistant packaging. When in use, the paper should be acclimated to room temperature for at least 24 hours. Additionally:

. Avoid exposing paper to direct sunlight. . Store all paper in the same area, avoiding humid conditions (room temperature between 20~25°C, relative humidity ideally between 45%~55%). . Store paper flat. . Do not store paper vertically.

Post-curling is a specific issue for double-sided printing. Adjusting the paper appropriately can prevent issues if the first side of the printed paper curls excessively.

2. Paper Size

The paper feed capacity of digital printing equipment is much smaller than offset printing equipment. Slight misalignment in paper cutting can result in frequent paper jams in digital printing equipment, significantly reducing productivity and efficiency.

3. Paper Dust and Fibers

Dust and fibers produced during cutting may be trapped between sheets of paper. During printing, these particles can disperse onto various components of the printing equipment, leading to component malfunctions and an increased likelihood of paper jams.

4. Paper Stiffness

Paper stiffness is directly related to paper thickness and humidity. For digital printing equipment, paper that is too thin may wrinkle and cause paper jams, while paper that is too stiff may not pass through the feeding system due to its limited flexibility. Therefore, specialized digital printing paper emphasizes paper stiffness to ensure the required mechanical properties.

5. Grain Direction

Paper exhibits significant directionality in many aspects. Longitudinal tension and fold resistance are stronger, making it easier to tear in the vertical direction. The transverse direction has weaker tension and fold resistance, making it more difficult to tear. The grain direction affects whether paper smoothly passes through complex, curved paper paths. When using digital printing equipment, the paper grain direction should be perpendicular to the feeding direction to avoid paper jams.

Choosing Between Offset Printing Paper and Specialized Digital Printing Paper

There are significant differences between offset printing paper and specialized digital printing paper. Thickness, density uniformity, surface roughness, and other factors are necessary conditions for producing high-quality prints on digital printing equipment. To achieve the best printing results, specialized digital printing paper is formulated according to specific requirements. Therefore, when both are printed on digital printing equipment simultaneously, the printing quality of offset printing paper is usually lower, as mentioned earlier, due to the influence of moisture content.

Currently, there are various opinions on the choice between offset printing paper and specialized digital printing paper. Many people believe that using offset printing paper is more cost-effective than digital printing paper. From a cost perspective, this argument seems valid. However, considering all hidden costs of running offset printing paper on digital printing equipment, this argument does not hold.

With the increasing demand for on-demand printing, the production time for products has greatly shortened. Downtime units affecting productivity have shifted from hours to minutes. If the job time for printing 100 sheets of paper is less than 2 minutes, the time required to clean the equipment jams and prepare the printing equipment again is twice the normal operating time. How much work can be completed during the time spent clearing jams? How much can production efficiency be improved without “downtime,” resulting in more profit? How much “additional” cost can be reduced by using specialized digital printing paper?

As a printed material, paper is indispensable in printing. In addition to selecting paper based on the specific characteristics of various printed materials, it is essential to store paper correctly and understand its characteristics to maximize the value of paper in production.

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