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24

2019-06

23 Major Factors Affecting Prepress Plate-Making Quality

Prepress plate‑making equipment accounts for a significant proportion of malfunctions due to external factors, and the causes are multifaceted. Consequently, solutions must be tailored to the specific circumstances. Through years of troubleshooting, the author has identified several common factors that frequently lead to equipment failures—factors that are intrinsically linked to machine breakdowns. Of course, other important contributing elements may exist that are not explicitly listed here; however, a thorough analysis of these key issues can help ensure reliable operation and prompt resolution of problems. The following summarizes these factors: 1. Dust: Plate‑making equipment, particularly advanced electro‑photographic and imagesetter systems, is highly precise. For such machinery, dust represents…

2019-06-24

24

2019-06

A Detailed Analysis of Color Printing Design Standards

According to the ink density ranges specified in the guidelines, any ink overprint sequence—YMC, YCM, CMY, CYM, MCY, or MYC—can be used. However, does each sequence produce the same color in print design? In fact, it does not. Even when solid densities are kept at precise target values, different overprint sequences still yield distinct red, green, and blue overprint colors, because the ink formulations employed in each sequence possess unique properties—for example, differences in ink opacity that affect coverage. Consequently, the surface energy of the dried ink film from the earlier‑printed (first‑printed) layer will influence the subsequent‑printed (later‑printed) layer…

2019-06-24

24

2019-06

Structural Analysis of Self-Standing Spout Packaging Bags

Stand-up pouches with spouts are an emerging type of liquid packaging that has evolved from the traditional stand-up pouch. The structure of a stand-up pouch with a spout is primarily divided into two parts: the spout and the stand-up pouch itself. The pouch portion shares the same basic design as a conventional four-seal stand-up pouch, though it typically employs composite materials to meet the diverse requirements of food packaging. The spout can be thought of as a standard bottle opening fitted with a drinking straw. These two components are tightly integrated to create a beverage package that facilitates easy sipping; moreover, because it is a flexible package, there is no difficulty in drinking, and once sealed, the contents remain stable without sloshing—making it an exceptionally ideal new form of beverage packaging. Stand-up pouch with spout

2019-06-24

14

2019-06

The Relationship Between Paper Properties and Print Color Appearance

As the primary raw material for printing, the performance of paper directly determines the quality of printed colors. Only paper with excellent properties can deliver superior color reproduction in printed materials. Therefore, accurately understanding the relationship between paper characteristics and print coloration, and selecting appropriate paper based on the specific requirements of the printed product and production process, is of great practical significance for enhancing product quality. I. The Relationship Between Paper Smoothness and Color Appearance Smoothness is a technical indicator used to assess the degree of surface irregularities on paper; it quantifies how flat, smooth, and uniform the paper’s surface is. Specifically, under defined vacuum conditions, it measures the time required for a fixed volume of air to pass between the test sample’s surface and a smooth glass surface at a specified pressure, with the unit expressed in seconds. A higher number of seconds indicates better smoothness. With improved smoothness, the contact between the paper and the printing plate becomes more even and complete, resulting in more thorough ink transfer from the plate or blanket and, consequently, better color reproduction. Conversely, poorly smoothed paper leads to uneven and incomplete ink transfer, coupled with strong ink absorption by the paper itself, which degrades color quality and often causes mottling or fading in the final print. Thus, for finely detailed prints—especially those with fine screen rulings and small halftone dots—it is essential to use paper with high smoothness to ensure faithful reproduction of the original artwork. II. The Relationship Between Paper Gloss and Color Appearance Paper gloss refers to the degree of specular reflection on the paper’s surface, expressed as a percentage. The higher the gloss, the more effectively the surface reflects light, producing a bright and vibrant appearance. In reality, paper surfaces exhibit both specular and diffuse reflection, which together reduce overall gloss. High-gloss paper yields more vivid print colors and enhances visual impact. In essence, the smoother the paper, the higher its gloss, and the more lustrous the resulting colors. While gloss and smoothness are closely related, gloss does not necessarily equate to smoothness; a glossy surface may not always be perfectly smooth. Considering these characteristics, selecting paper with appropriate gloss levels according to the nature of the print job is highly practical. For example, when printing text-heavy publications, papers with moderate gloss are preferable to avoid excessive reflection that could cause eye strain over prolonged viewing. By contrast, for graphics‑oriented prints, high‑gloss paper is recommended to achieve uniform, rich, and visually appealing colors. III. The Relationship Between Paper Whiteness and Color Appearance Paper whiteness denotes the paper’s ability to reflect light uniformly after exposure, also referred to as brightness, and is expressed as a percentage. Higher whiteness means the surface can more accurately reproduce the tonal qualities of ink colors. This is because white paper reflects all wavelengths of light that pass through the transparent ink layer, effectively restoring the original color balance. Consequently, high‑whiteness paper can reflect nearly all light, yielding vivid, pleasing colors and excellent visual effects. In contrast, low‑whiteness paper absorbs only part of the light spectrum, failing to faithfully render contrasts between light and dark areas and often leading to color shifts—such as yellowish, reddish, greenish, or bluish tints. When the paper itself exhibits color bias, the resulting hue on the printed page represents a combined effect of ink and paper, inevitably causing color deviations. To address this issue, during printing, it is crucial to compare the paper’s whiteness and any color biases against the original artwork and implement corrective measures accordingly. For instance, if the paper has a yellowish tint, deep yellows, peacock blues, or bright reds should be avoided; instead, ink choices should align with the paper’s inherent color characteristics to mitigate color shifts. Alternatively, color correction can be achieved through adjustments in the ink formulation process. IV. The Relationship Between Paper Absorbency and Color Appearance Paper absorbency refers to the paper’s capacity to take up binders and solvents contained within the ink, typically measured as a percentage. Also known as ink absorption, this property significantly influences the vibrancy of print colors and the sheen of the ink layer. Highly absorbent paper tends to produce prints with muted colors and lacking gloss, as most of the ink’s binder is absorbed by the paper fibers, leaving pigment particles insufficiently protected. As a result, the ink film becomes fragile, prone to flaking or “powdering.” On the other hand, if a paper’s absorbency is too weak, the ink layer adheres poorly, dries slowly, and may leave smudges on the reverse side of the print. Therefore, selecting paper with suitable absorbency based on the intended use of the print is vital for ensuring consistent print quality. For example, newsprint with strong absorbency is ideal for fast‑turnaround, cost‑effective newspaper printing, while delicate, high‑color‑intensity prints require papers with lower absorbency, such as glassine or coated art paper. Among the various paper properties affecting print coloration, gloss and absorbency stand out most prominently. The combined impact of a paper’s absorbency and gloss on print color quality is termed “surface efficiency,” which can be calculated using the following formula: PSE (%) = (100 − A (%) + G (%)) / 2 Where: PSE stands for paper surface efficiency; A represents the paper’s ink absorbency; and G denotes the paper’s gloss level. Process testing demonstrates that when paper surface efficiency is high, under identical processing conditions, ink color intensity reaches its peak while color deviation and gray tones are minimized. Research and testing of paper surface efficiency constitute an important step toward data‑driven, standardized production processes, playing a critical role in correcting color deviations and ensuring consistent print quality. Thus, gaining a clear understanding of how different paper properties influence print coloration is undoubtedly beneficial.

2019-06-14

The Relationship Between Paper Properties and Print Color Appearance
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