Smoothness: Smoothness is the time in seconds that a certain volume of air passes through a gap between the surface of the sample subjected to a certain pressure and the glass surface under a certain degree of vacuum. 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 paper surface will be in contact with the print head or the drum when printing or copying, the more the ink is transferred, and the better the color rendering of the print. On the contrary, paper with poor smoothness, ink transfer is not uniform, insufficient, and the paper has a strong permeability to the amount of ink, and the color rendering effect is also poor, and it is often easy to make the printed ink color and light. Therefore, when choosing, try to use paper with good smoothness, so the effect will be better.
Gloss: Gloss is the degree of specular reflection on the surface of the paper, expressed as a percentage. The higher the gloss of the paper, the more the surface can reflect light like a mirror, and the more it shows the bright appearance. In fact, in addition to specular reflection, there is diffuse reflection on the surface of the paper, which reduces the gloss of the paper. For papers with high gloss, the more vivid the printed ink, the better the visual effect of the ink. It can be said that the smoother the paper, the higher the gloss, and the higher the gloss of the printed product. There is a close relationship between the gloss and smoothness of the paper, but the gloss is not smooth, and the shiny surface of the paper is not necessarily a smooth surface. From the point of view of the glossiness of the paper, it is very practical to select the appropriate paper according to the characteristics of the print. For texts and texts based on text, it is advisable to use paper with a general gloss to avoid reflection, so that the eyes will not be fatigued for a long time. For printing plates with printed plates as the mainstay, paper with high gloss should be used to make the printed inks uniform, thick and bright.
Paper whiteness: Paper whiteness refers to the ability of paper to be totally reflected after being exposed to light. It is also known as the brightness of paper, expressed as a percentage. The higher the whiteness of the paper, the more the surface of the paper can accurately represent the color of the ink. This is because the white paper reflects the color light synthesized by the color reduction of the transparent ink layer. Therefore, the paper with high whiteness can reflect almost all the color light, making the printed ink color bright and pleasing, and the visual effect is good. Paper with low whiteness, because it only absorbs part of the color light, can not faithfully express the contrast between the light and dark parts, and easily cause color cast. If some appear yellowish, some appear reddish, some appear greenish, some appear blue and so on. When the paper itself is color cast, the color printed on the paper is the effect of the combination of ink and paper. This will inevitably lead to some color cast. Based on this situation, it is necessary to white the paper when printing. The degree of color and color cast are analyzed against the original, and appropriate measures are taken to achieve the purpose of correcting the color cast.
Absorbency of paper: The absorbency of paper refers to the ability of paper to absorb the binder and its solvent in the ink, usually expressed as a percentage. The absorbency of paper is also called ink absorption, and its strength is very sensitive to the performance of hue and gloss of the ink layer. Paper with strong ink absorption, the ink color of the printed product is easy to fade, and the ink layer lacks gloss. In addition, since the binder in the ink is mostly absorbed by the fibrous structure of the paper, the pigment particles are not sufficiently protected, and the ink film on the printed matter is not strong, which tends to cause "pulverization" of the print. On the other hand, if the ink absorbency of the paper is too weak, the printed ink layer will not adhere well, and the print will not be easily dried, which may easily cause the back of the print to be dirty. Therefore, according to the use characteristics of the printed products, the paper with the right absorption can be selected to ensure the quality.
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