The influence of paper on ink color is well known, which depends first on the color and smoothness of the paper , and secondly on its absorption properties (regardless of the drying of the ink ), and the former is the main one. Only when the brightly colored ink is printed on paper with good whiteness , can its color effect be fully exerted. It doesn't do much when printing brightly colored inks onto heavily grayed paper.
We know that the color difference of the paper itself is very large. From the CATF (Graphic Arts Technical Foundation-Printing Technology Foundation) color wheel diagram in Figure 18-19, we can see the difference between the color and grayscale of the paper. B on the left represents blue-white fluorescent paper. A point in the middle is neutral. The Y-R on the right is the paper from yellow phase to pink phase . The upper paper is more greenish and the lower paper is more magenta.
Figure 18-20. Hue and grayscale of color printing ink on coating-paper and offset paper....
Generally speaking, the color of printing paper can be divided into three categories, namely blue and white, neutral and warm white. The latter can be divided into two types: yellow phase and magenta phase.
Since the GATF color wheel diagram is a binary diagram expressing hue and grayscale, the result of yellow newsprint with relatively low brightness is similar to that of paper with relatively high brightness. Because in this kind of picture, the brightness is on the same plane.
The difference in the surface of the paper will also affect the color of the ink. For example, the difference between coated paper and non-coated paper is the saturation or intensity of the color . Of course, the grayscale and hue are also different.
Figures 18-20 illustrate the printing of chromatic plate inks on coated and offset papers . For yellow, the two are relatively similar, but for it is better, such as increased grayscale, warmer blue and magenta, etc.
Figure 18-21 is a diagram of an intensity color wheel with a white center and a density of zero, and an outer ring of density 2. It can be clearly seen from the figure that the strength of the ink on the offset paper is lost, among which red and blue are the most significant.
Generally speaking, when the ink is printed on smooth coated paper, a satisfactory effect , but not on offset paper. This is caused by light diffusion, which limits the intensity of the secondary color, especially black. worse. Table 18-11 indicates the percent efficiency of magenta and cyan inks on three different papers:
Figure 18-21 Hue and intensity of color printing ink on coated paper——and offset paper ....
Figures 18-22 show the light reflectance of a red ink printed on two different papers . In the picture A is the situation printed on coated paper, and B is the situation printed on offset paper. Offset paper has a rough surface, so it reflects less light.
It can be seen that when printing on paper or darker color, the effect will not be satisfactory, which is common sense.
For paper with loose structure, because it can absorb more oil exposure, when the amount of ink is the same, its printing effect is not as good as that of paper with small absorption and dense structure .
Among all kinds of paper, the flat and nearly neutral coated paper is the most suitable paper for color reproduction. This is a fact that has been proven all over the world .
From the above, it can be seen that the quality of the paper will have a wider impact on the color of the ink. The hue, lightness, and saturation of ink can vary greatly depending on the quality of the paper. Therefore, if you have good printing technology and oil quantity, but without high-quality paper, it is still impossible to get satisfactory printing results. This should cause us to pay enough attention, because this view is not deep in the concept of most printing workers and ink workers.
Figure 18-22 Reflection of different papers to the same ink
