Why there is color difference during offset printing

Because after the offset printing packaging printing products, the pattern level is good, texture is strong, color is rich, the current packaging printing or the vast majority of offset printing. Modern offset printing machine multi – color one – time forming efficiency, favored by customers. However, offset printing also has a fatal weakness – compared to other printing methods easy to produce chromatic aberration. It has high technical requirements for the operators of offset printing, especially the control of ink balance, especially the standardized data operation.

As a packaging printer, we must pay attention to the color difference in offset printing, carefully analyze the causes of color difference, and take effective measures to overcome it.

1. The effect of paper on color

1) The whiteness of different paper on the printing ink layer color show different effects.

2) The gloss of printed matter depends on the gloss and smoothness of the paper. If the gloss and smoothness of the paper is high, we observe that the color is basically reflected through the ink layer, the main color saturation is high.

3) The same color of the ink, under the same conditions, printed to the absorption of different paper will have different gloss and color printing.

2. The effect of paper surface treatment

Packaging printing in addition to printing, there are a lot of post-press processing technology, which is a considerable part of the paper surface treatment, including film (light film, subfilm), glazing, calendering, oil, light, and so on. Printed matter after these surface treatment, there will be different degrees of color changes. Therefore, as the packaging offsctdruckereien printed matter, if there is post-press processing process, post-press processing must be considered into the physical and chemical changes, so as to determine the density of the ink layer and L*a*b*.

3. Printing process operation

The influence of dry regression density value, wetting fluid size, printing speed, printing pressure.

4. The effect of bad printing

Printing plate is one of the quality of copy. In the printing process, only the plate of good reducibility, deformation, wear and tear to ensure a better layout of ink transfer stability.

5. The effect of bad roller

Offset printing technology, printing can get uniform ink, cots quality has a very important role. There are three kinds of cots: transfer roller, uniform roller and inking roller. The roller's elasticity, viscosity, center, hardness and surface finish, largely determine the quality of ink printing.

6. The effect of light source characteristics

Offset printing in the observation of color must have a light source, no light can not see the color, but if the characteristics of the light source is not the same, then the color difference will be very big. In general, our requirement is to view color in natural light (i.e. standard light source). If the use of ordinary light bulbs as a source of color, then the color will appear yellow, it is difficult to accurately identify the color, the final printing will produce serious color slant.

7. The effect of ink blending

Packaging offset in addition to four color ink, there are also monochromatic ink. Monochromatic ink is generally required to print their own deployment. Then, we must record every printing ink formula proportion, to have data control – record the ink product name, dosage. 

8. The effect of bad equipment

Keep the machine good performance, is to improve the quality of printing ink reliable guarantee.

In short, the reason of color difference, we must combine the actual work of the situation, analysis and study, find out the solution, make the packaging of offset printing products as much as possible to reduce the chromatism, guarantee in allowed within the prescribed scope of color, to improve the packing quality of offset printing products, to meet customer demand for us.

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