Prepress quality control of gravure printing from three aspects

Pre-printing control In order for the printing process to proceed smoothly, it is necessary to effectively control the work of plate making, color correction, and proofing before the formal printing. Platemaking When designing, you need to modify the design of the manuscript according to the characteristics of gravure printing, so that it can be more suitable for printing needs.

1, overprint

For the need of overprinting, small lines and texts cannot use multi-color overprinting. There should be no small anti-white characters on the pattern of the chromaticity. It should not leave blank on the chromatic patterns, and put on other fine texts. The version, black, blue, red, yellow version as far as possible between the other color version. For printing needs, the bar code should be arranged so that the line direction is consistent with the direction of the cylinder's circumference. The color should be guaranteed to be in the direction. If there are conditions, it is best to separate the large ground background from the hierarchical pattern version, and use the special edition as much as possible. Hanging screen version must fully consider 80% and 5% of these two color jump areas, and the limit of the screen points when the gradient is suspended is more than 10%.

2, ink color

The deployment of ink formulation includes two aspects: on the one hand, it refers to the adjustment of ink printing adaptability, such as the viscosity and concentration of ink, the principle is to adjust the viscosity of the ink with a diluent (solvent) to adjust, according to the printing roller and machine before printing. The condition of the ink is determined in the case of the stage. In the printing process, the solvent is often added according to the volatilization of the solvent, so as to ensure the viscosity of the ink is constant; when the ink is to be diluted, the diluting agent (oil transfer ink) must be used.

Another aspect of ink formulation refers to the formulation of ink colors. In this regard, the following points need attention: Observe the color of the light source as much as possible using the standard light source (D65), if there is no standard light source, it is better to have a sunny north direction. In the preparation of spot colors, primary inks should be used for blending so that the brightness and saturation of ink inks can be guaranteed. Color matching is performed with as few ink colors as possible. The more colors, the greater the color matching error and the greater the difficulty of rematching. Proofing, a set of printing plates, must confirm a standard proofs. Some manufacturers take the sample draft of the plate making factory as a standard sample, and they cannot be sampled at the time of final delivery. Therefore, the printing machine must be used for proofing before printing, and the customer or the relevant person will confirm it as a standard sample.

3, proofing

The printing of standard samples should be carried out under normal printing process conditions, so the following points should be noted when proofing: The most basic printing process conditions are selected. The ink viscosity is chosen to be as low as possible. Primary color inks are to be added, and the use of contaminated ink that has been repeatedly used for proofing should be minimized. It is forbidden to perform all non-standard operations in order to over-pursue the effect when proofing, such as increasing the concentration and viscosity to increase the hue, adjusting the pressure, and scraping the blade to increase the ink transfer rate. The ink must be mixed before use, especially spot-color inks. The spot color inks prepared by oneself must be accurately recorded and recorded for later reference. Try to reach the normal printing speed when proofing. If the conditions permit, after confirming the basic color of the sample, a certain number of products are printed first, then the sample is confirmed as a standard sample, and sealed as a file data. After confirmation of the standard sample, the connected 2~3m should be taken as the equivalent standard sample, and it should be properly stored in a place without heat source and ultraviolet rays, and the cut portion should be used as the printing sample after each printing.