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Affect the color printing color reproduction of the main factors
Feb 07, 2018

There are a number of factors that affect the color reproduction of images when they are reproduced on a press, such as dot gain, print order and overprinting, ink hue and field density, ink temperature and viscosity, water supply (offset), paper properties, plates Layout shades, printing pressure.


1. Network expansion


In the printing, there will always be outlets expanded, but the expansion of more than a certain range will have a lot of quality problems. This enlargement will reduce the contrast of the image, and darken the entire image, dull dot matrix dot control, rapid changes in the color hue copied, when the printing network of images of various colors to expand at the same time, the overall image becomes darker. When only one of the color dots is enlarged, the copied image will have a color cast. For example, when the coverage of the magenta color version is enlarged in the middle and the color of the printed image is reddish when the 50% Red, neutral color turns pink, green becomes dirty. Printing pressure and field ink density all affect dot gain. Small changes in printing pressure will make a significant change in the entire printing image; dot density increases, the dot gain increases, the image has a significant impact on the harmony of the dark color.


2. Printing sequence and overprint


In color image printing, inks are colored and overprinted, resulting in poor color overprint, color mixing and disorder. The arrangement of printing color sequence has a great influence on overprint color effect. For multi-color printing presses, the printing time of each color ink is short, the printing ink is overprinted on the surface of the first printing ink, which belongs to the printing state of "wet and wet". The ink printed on the paper in the overprinted color is superior to the ink printed on the wet ink surface. Two colors of ink as long as the reverse order of color, overprint color hue, brightness and saturation may be different. Such as cyan and magenta ink overprinting, first printed after the green color, overprint color partial cyan; first printed after the red, green, overprint color red. In order to get a good overprint effect, the color sequence after a reasonable arrangement of the viscosity of various colors of ink.


3. Ink hue and field density


Printing inks used in the production of varying degrees of color cast, so that the printed image color cast, as far as possible the use of less color ink for color printing. The density of the solid ink on the printed image surface determines the print image tone and hue reproduction range. The higher the density on the ground, the wider the tone and tone reproduction range. Field density is small, so that the image color saturation decreases, overprint color weakened.


4 ink temperature and viscosity


Ink viscosity is a very important parameter in printing image reproduction. The general gravure printing liquid ink, inking device is not uniform ink and channeling ink mechanism, the ink viscosity by adding an appropriate amount of ink tank to control. Offset and embossing commonly used viscous ink, this ink viscosity. In order to make the ink evenly from the plate to the paper surface transfer, offset and embossing machines have uniform ink and channeling ink device. The ink is squeezed, sheared and separated during the transfer and flattening of the rollers between these devices. Roller to overcome the internal friction of ink and work, leaving the ink roller surface temperature is transferred, and was beaten in the process, subject to extrusion, shear and separation. Roller in order to overcome the internal friction of ink and work, leaving the ink roller surface temperature, the viscosity of the ink is passed down. After the ink is thinned, the amount of ink carried on the roller surface is reduced, the amount of ink delivered to the paper surface is reduced, the tone and tone of the printed image are changed, and the consistency of the printed image is damaged. Studies have shown that: printing machine boot printing, printing images generated color deviation of 60% of the reasons are roller temperature changes caused.


5. Offset ink balance


Offset printing ink directly affects the image quality of the balance. The small amount of water will make the plate dirty, paste version; water ambassador ink emulsification, so that the printed image color saturation decreased.

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