The standardization and dataization of color printing operation

2 Normalization and dataization of the plate making process

Platemaking is the key process for the offset printing process. There are many variables. As the principle of color printing plate making, the first is to stabilize various variable factors as much as possible, and the second is to provide the specification basis for the previous process from the post process.

1) Standardization of platemaking conditions

1 environmental conditions

The room temperature should be maintained at 20 °C ~ 25 °C, and daily cleaning the environment; if the grid fluctuations exceed 10% of the rated voltage, you need to use a regulator; occasions with poor water quality, the application of distilled water to prepare the developer.

2 raw material requirements

Fixed PS version of the brand and model, in the change model and batch number, the PS version should be routinely tested to confirm the quality of the PS version in order to modify the printing process parameters. Through the instructions, confirm the general requirements of the PS plate for the light source and development conditions, so as to avoid the situation of raw materials and equipment and processes inconsistent; confirm the PS plate and kit drug delivery date, shelf life, storage conditions should be in the normal range.

3 original (yang picture) requirements

Solid density ≥ 3.5D, gray Dmin ≤ 0.07D; mesh, line edge clear; graphic location is correct, the size is appropriate, consistent film, clean layout.

4 Equipment requirements

The spectrum of the printing machine is suitable (350-450nm), the light intensity is above 3000W, and the light intensity is stable. The illumination intensity of the printing plate is even. The vacuum pumping system is normal and the glass surface of the printer is clean.

5 development requirements

PS plate development temperature, speed, concentration (supplement) should be performed with reference to the use of kits and remain constant.

2) Standardization of plate making operation

1 Before the plate making operation, it is necessary to accurately understand the requirements of the imposition, the requirements of the edition order, the layout, the folding, etc., and draw an accurate table paper.

2 After receiving the film, it is necessary to first check the number of soft films, whether they are patched, and whether they are complete; check whether the film is accurate, whether the rules are complete, and whether there are any color marks, etc. Bit accuracy; Check film density, bottom ash condition, film scratches, horseshoe prints, dirty tracks, running light, etc.; control print samples check pictures, titles, headers, report eyebrows, edition hearts, article areas, etc. Photographs were corrected and re-emerged.

3 To align the crosshairs, the table paper and the film base should be laid well, the hanging nails should be hung up, the crosshairs should be checked again after the spelling is finished, and the four sheets should be re-inserted to check the quality of the imposition. Order, the direction of the film surface and so on.

4 After the imposition, use 10 times more magnifier to check the registration condition to ensure that the imposition error is less than 0.1mm.

5 Sunscreen newspapers must use printing plate hanging nails, and check the exposure parameters are appropriate.

6 The film should be flattened on the printing machine, and the vacuum must be applied. After the vacuum is drawn, check whether the film has run and dust.

The determination of the print time can be determined using PS plate test strips. 1% outlets, 2% outlets, and 3% outlets. The third gray ladder feet exposed.

8 Punch parameters should be consistent. Liquid medicine should be replaced promptly and kept clean. After finishing the plate, check the layout and correct it. Brush glue must be uniform.

3) Main points of normalization process of plate making process

1 Imposition registration error ≤ 0.03mm;

2 imposition film base transparency D ≤ 0.03;

3 The plate shape error and thickness error should be within the allowable range of printing equipment;

4 The degree of vacuum of the printing machine should be within 0.08Mp;

5 The exposure time of the print was tested with Bruner test strips or Forge test strips. 1% dot network was used, 2% dot nets were used, 3% dot nets were all, and the median expansion was <15%, and 98% dot paste was used. A latent image appears in the density of 0.4D, and the 4 μm fine line is exactly reproduced.

Due to the timeliness of the newspapers, many newspapers gave up the proofing process in order to hurry up. Some newspaper companies use color printer proofing and screen soft proofing without affecting the reporting time. This is a far cry from the effect of mechanical proofing, and far from the actual effect of printing, because of the color gamut of inks. There is a big difference, and the way of reproduction is very different. Therefore, ink-jet proofing and screen soft proofing can only serve as a reference.

For most newspaper companies, color printer proofing is only used for text proofing. Screen soft proofing can only check for the presence of color shifts in the image. It does not play a role in verifying the plate making effect, determining the printing parameters and providing proofs for printing. With the continuous application of CTP technology in newspaper printing, the proofing process will be a small step and will become more and more important. Now, the color scale output by the digital proofing system (it comes with the system) or the standard image chromatogram can be basically consistent with the actual printing after being adjusted by the calibration software. How to formulate a proofing standard suitable for newspaper printing needs continuous exploration and research to meet the needs of rapidly developing CTP technology as soon as possible. (to be continued)