Talk about paper performance and color effect

Paper is the main raw material for printing, and its performance determines the quality of printing ink. Only good performance paper can get better print color effect. Therefore, a correct understanding of the relationship between paper performance and print color, according to the characteristics of printing products, process conditions, a reasonable choice of paper for printing, has important practical significance for improving product quality.

First, the relationship between paper smoothness and color rendering

Smoothness is a technical index for evaluating the degree of unevenness on the surface of a paper sheet, and is a physical quantity indicating that the paper surface is flat, smooth, and uniform, that is, under a certain vacuum condition, a certain volume of air, from the surface of a paper test sample under a certain pressure and smooth The time required to flow between the glass surfaces is measured in seconds. The higher the number of seconds, the better the smoothness of the paper. The better the smoothness of the paper, the more uniform and complete the contact between the paper and the printing plate at the time of printing, the more sufficient the transfer of the ink layer on the layout (relief) or the blanket, and the better the color rendering effect of the print. Conversely, poor smoothness of the paper, ink transfer is not uniform, and inadequate, and paper penetrating the amount of ink is strong, the effect of color is also poor, often easy to make ink prints hair, light hair. Therefore, for fine-printing products, the finer the network cable and the smaller the dot diameter, the better the paper should be printed with good smoothness so that the original can be reproduced well.

Second, the relationship between paper gloss and color rendering

Paper gloss refers to the degree of specular reflection on the paper surface, expressed as a percentage. The higher the gloss of the paper, the more mirror-like the light reflected on the surface, and the brighter the appearance characteristics. In fact, in addition to the specular reflection, there is diffuse reflection on the surface of the paper, which causes the paper gloss to decrease. For paper with high gloss, the color of the printed ink is also brighter, and the visual effect of the ink is also better. It can be said that the smoother the paper, the higher the gloss and the higher the gloss of the prints. The glossiness and smoothness of paper are closely related, but the glossiness is not smoothness. The shiny surface of paper is not necessarily a smooth surface. From the perspective of the glossiness of the paper, it is of great practical significance to select suitable paper for printing according to the characteristics of the print. Such as the text of the layout of the main text of the book, should choose the general paper gloss, so as not to reflect, so that the eyes do not look tired for a long time. The printing of the plate-based layout, should use high gloss paper, so that the ink is uniform, thick, bright and pleasing.

Third, the relationship between paper whiteness and color rendering

Whiteness of paper refers to the ability of paper to reflect light after being irradiated with light, and it is also called the brightness of paper, expressed as a percentage. The higher the whiteness of the paper, the better the surface of the ink can accurately represent the color characteristics of the ink. This is because the white paper reflects the color light synthesized by subtracting the color of the clear ink layer back. Therefore, paper with a high degree of whiteness can reflect almost all the shades of light, making the inks look bright and pleasing and have good visual effects. The paper with low whiteness, because it absorbs only part of the color light, can neither express the contrast of the light and dark parts truthfully, but can easily cause color casts. Some appear yellowish, others appear reddish, some appear greenish, and others appear blueish. When the paper itself color cast, the color printed on the paper is the effect of both the ink and the paper integrated color, and this will inevitably appear some color cast situation, based on this situation, when printing is necessary on the white paper Degrees and color casts were analyzed against the manuscripts and corrective measures were taken to correct the color cast. For example, when the color of the paper is yellow, it is not appropriate to use inks of dark yellow, peacock blue, and red, etc., that is, the ink should be used properly to eliminate color cast. On the other hand, the color shift can be corrected by the ink adjustment process.

Fourth, the relationship between paper absorption and color rendering

Absorption of paper refers to the absorptive capacity of the paper to the binder and its solvent in the ink and is usually expressed as a percentage. Absorption of paper is also called ink absorption. Its strength is very sensitive to the appearance of printing hue and the glossiness of the ink layer. Paper with strong ink absorption, the hue of printed ink is easy to fade, and the ink layer lacks glossiness. In addition, since the binder in the ink is mostly absorbed by the fibrous tissue of the paper, the pigment particles are not sufficiently protected and the ink film on the print is not firm, and the phenomenon of “powdering” of the print is likely to occur. Conversely, if the ink absorption of the paper is too weak, the ink layer of the printed product will not be adhered securely, and the print will not be easily dried, which will easily cause the back of the printed product to become dirty. Therefore, according to the characteristics of the use of printed materials, select the appropriate absorption of paper for printing, in order to better ensure the printing quality. For example, newspapers should use strong absorbing newsprint to meet the characteristics of high-speed, emergency, and economical use. The fine print products, the color should be bright to require weak paper absorption, such as glass cards, coated paper and so on. Among the paper properties that affect the color rendering effect of printed products, the most prominent is the glossiness and absorbency of the paper. The combined effect of the paper's absorbency and gloss on the ink effect of the print is called the surface efficiency of the paper. It can be calculated by the following formula:

PSE(%)=(100-A(%)+G(%))/2

In the formula: PSE stands for the surface efficiency of the paper; A is the ink absorption capacity of the paper; G is the glossiness of the paper. Process testing can show that when the surface efficiency of the paper is high, the color intensity of the ink is the highest under the same process conditions, while the color shift and gray scale are the minimum. The research and testing of the surface efficiency of paper is an important part of realizing the data and standardization of the process. It is of great significance to better correct color cast and to ensure the quality of product printing. Therefore, it is necessary to correctly understand and understand the performance of paper on printed products. The effect of color rendering is undoubtedly beneficial.

Source: Corporate Blog Network