Why the color of spot-color ink printing often causes problems is generally caused by the incorrect formulation of spot-color ink. Spot ink formulations are the most important factor affecting spot color printing. but. Sometimes printed jobs with the same spot color formula. The color difference between one lot and another is also very large. Why is this again? This is because in addition to spot color formulations. There are many other factors that affect the color of spot color ink printing. Let us now analyze these factors one by one.
Ink thickness
The thickness of the ink layer refers to the thickness of the ink deposited on the surface of the substrate after printing. In spot printing, the dot area rate is sometimes used to control the thickness. To get a lighter color.
The ink thickness is in addition to spot ink formulations. One of the most important factors affecting the color printing of spot colors. Table 1 and Figure 1 are sufficient to illustrate the effect of ink layer thickness on print color. Table 1 is the color change of the four inks when the thickness of the ink layer is slightly changed. It can be seen from. About 0.1um ink layer thickness changes will cause 1.5 ~ 4.3 Delta Eab color difference. Obviously this effect is great. Figure 1 shows the relationship between ink layer thickness and print density. Within a certain range. Density increases with the thickness of the ink layer and this tendency is more pronounced at smaller thicknesses.
When doing spot color printing. The effect of the thickness of the ink layer on the color of the print must be fully considered. When spot color inks are dispensed. Proof ink thickness. It should be as close as possible to the thickness of the ink in the actual printing. In order to accurately predict the color of the spot color ink. For comparison with standard color samples. Secondly. When printing, the thickness of the ink layer of one batch of job and another batch of job and the job printed before and after the printing process should be consistent as much as possible. To reduce the color cast of spot colors.
Ink hiding power
Hiding power is the ability of the ink to cover the background. The better the hiding power, the poorer the transparency of the ink. The ink color is less affected by the color of the underlying substrate. The hiding power is related to the concentration of the pigment in the ink and the ratio of the refractive index of the pigment to the refractive index of the binder.
The hiding power of the ink and the thickness of the ink layer affect the transparency of the ink layer. The stronger the hiding power, the thicker the ink layer. The worse the transparency of the ink layer is, the smaller the printing color of the ink is affected by the printed substrate. Spot inks are mostly translucent or opaque. When choosing the ink formulation, the effect of the opacity of the ink layer on the spot color printing should also be taken into account according to the actual situation. In order to select the formula with a suitable hiding power.
Underlying substrates
The ink used for printing is mostly transparent or translucent. In this way, the substrate can reflect light and the reflected light can enter the human eye through the ink film. It will affect the color of printed products. Therefore, the influence of the color of the underlying substrate on the color of the printed matter cannot be ignored. In addition. The different absorption of the ink by the substrate also affects the color of the final print. For example, the effect of the same ink printed on coated paper and uncoated paper is very different. therefore. The color of the underlying substrate and the absorbability of the ink are also important factors affecting the printing color of the spot color ink.
In order to reduce the influence of this factor on the color of spot ink, what should be done? The first is to use the same paper as the actual printing when preparing the test color sample for ink preparation. To test the various indicators of printing paper, to ensure that there is no great fluctuations in paper quality. In this way, from the beginning of ink dispensing to the end of printing, the paper quality remains uniform. The influence of the substrate on ink color is also controlled.
What needs special note is that not only the color substrate affects the color of the ink. The same is true for white substrates. This is because the white substrate also has its hue and lightness. The color of different white substrates is different under the photometer. These nuances also affect the color of the more transparent ink.
For translucent or opaque ink printed on plastic film. The impact of the properties of the substrate on the color of the print is not the same as the above. At this time, the unprinted surface of the film becomes more important. Because the human eye sees the color of the printed product from this side, the surface properties and twist of the film. It has become a major factor affecting the color of printed products.
Source: Shenzhen Printing Network