Offset printing common problems and solutions (on)

Shaiban is the last step in the plate making process. It will be copied on the metal plate through the printing process and the plate will be made for printing and proofing.
Dots in the printing process changes in law The purpose of offset printing printing is to accurately transfer the graphics on the film to the plate above, due to the length of exposure time, developer ratio, developer concentration, development time, different The depth and level of the graphic and network outlets have changed greatly, especially in the two domains of bright and dark tone.
In the case that the developer ratio, temperature, developing time, intensity of the printing plate, intensity, sprinkling distance, and temperature and humidity are constant, if the exposure time is extended, the dots can be reduced and the whole graphic text will be lighter. If the exposure time is properly reduced under the circumstances, the outlets will become larger and the whole picture will be darker.
Therefore, with the extension of exposure time, special attention should be paid to the problem that small outlets in the bright-tuning area, ie, 10% or less, will be lost.
The reduction of exposure time should prevent the dots at the depth of the pattern, that is, the problem of overprinting of more than 80% of dots.
In order to do a good job in the quality of printing plates, it is necessary to clarify the requirements, roles, and network quality standards of printing, printing, imposition, and retouching.
1. The role of outlets:
1) Decompose the combined colors;
2) Sensitive fat units, lipophilic properties on offset printing plates;
3) Print screen brightness saturation;
4) The amount of ink, the size of the adjustment.
2. Network quality standards:
1) The print dot density (blackness between 2.30-3.0) reaches this density to ensure quality.
2) The outlets are clean and clean.
3) The dot is accurate and the dot shape is positive.
4) According to different manuscripts, paper, printing machinery capabilities, the distance to observe the situation to select the number of network lines, close observation, the finer the network cable.
5) Virtual halo and so on. All in all, dot density and color, the formation and evolution of outlets, transfer should be controlled by data standards. The outlets require a complete hierarchy of adjustments, with good color balance, high definition, and no fog. The density dot contrasts are consistent with the data. The dot types, specifications, dimensions, and angles of the outlets are accurate. The layout is clean and tidy. The outlets are black, solid, smooth, and flat, with accurate specifications.
Printing process requirements: Under normal circumstances require 2% -97% of the outlets appear, 2%, 5%, 8% of the small outlets are not lost, the middle tone 50% no mutation to expand and level, dark tone part 95% -98 % is not paste version, that is, PS version 2%, 50%, 98% of three outlets. Flat and concave version (PVA version) 3%, 90% two-point reduction, 50% outlet expansion of about 5%.
The printing plate encounters the following types of processing methods: 1. When the printing version encounters a black dot difference in the soft version of the graphic text, to achieve the printing plate graphic and text, the exposure time should be reduced to achieve the graphic text. The purpose of sun drying.
2. The printing plate should be sun-dried to increase the exposure time to achieve the purpose of lightening the text.
3. When the printing plate is to be hardened, the thickness of the photosensitive film can be increased and the exposure time can be increased to make the printed plate graphic harder. This is mainly due to the sunken gravure (PVA) mainly in the polyethylene. Increase the thickness of alcohol emulsion coating. (To be continued)

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