Offset printing 1000 questions (346-356)

346. What are the causes and solutions to the troubles caused by post-processing?

A: The cause of the malfunction: In addition to dirty (in addition to dirty not thoroughly rubbed, in addition to dirty after the flush is not complete, in addition to the dirty method caused by improper layout, in addition to the dirty agent acting time is short, in addition to dirty agent used wrong or recession); baking version Improper (burning fluid not evenly coated, baking temperature is too high, baking time is too long); Improper ink (dry layout, incomplete after ink extraction); improper protection of the protective glue (dirty protective tape or dirty tape , The protective glue is thin, and when the adhesive layer is not dry, it is overlapped and stored); the operation process is not clean; after the plate making, it is stored under high temperature and high humidity conditions.
Solution: in addition to dirty carefully; in addition to dirty should be thoroughly washed clean; should not use tools scrape to grind dirt; in addition to dirty agent action time should be maintained for 20 to 30 seconds; use of good quality removal agent; standard baking version of the operation ( The best temperature and time for baking the plates are tested); the ink should be removed in the slightly wet state of the plate; the residual ink should be thoroughly washed after the ink is drawn; the wiper protective rubber should be used to operate the product; clean glue and cloth should be used; Hold your mouth and tip.

347. What are the main performances of the poor performance of the printing and graphic basics?

A: The poor performance of the printing plate graphic base refers to the fact that the graphic basis is not strong, and the stability is poor. When printing, the corrosion resistance, wear resistance is poor, and the printing force is low; the ink affinity is poor, the ink is slow and the ink is uneven.

348. What are the main factors affecting the poor performance of printing and graphic basics?

A: The main factors affecting the poor performance of the printing plate graphic and textual basis are PS body quality problems (photosensitive adhesive coating), exposure problems, development problems, post-processing and preservation issues.

349. What are the causes and solutions to the problem of poor basic performance of printing plate and text caused by exposure?
A: The cause of the malfunction: the exposure time is too long; the original density is insufficient; the secondary exposure is excessive;
Solution: correctly determine the exposure time; remake the original; if the secondary exposure in addition to dirty should be appropriate to reduce the main exposure time; application of black paper and effective shading.

350. What are the causes and solutions to the problems caused by poor basic performance of the plate due to development?

Answer: The cause of the malfunction is that the development time is too long; the temperature of the developer is too high; the alkali of the developer is too strong; the water washing after the development is not thorough.
Solution: Regulate developer preparation, development conditions and operation.

351. What are the causes and solutions to the malfunctions of poorly-printed graphics and text caused by post-processing?

Answer: The cause of the malfunction: the water on the surface of the plate has caused the dirt to infiltrate into the graphic part; the water is not completely washed after the dirty part; the ink is not extracted or the ink is insufficient; the protective glue is used improperly (without using the correct protective glue and glue solution Concentration, non-uniform coating; drying temperature is too high; contact with strong light after coating.
Solution: In addition to the dirty must be in the state of dry plate; In addition to dirty after thorough washing; PS version of the poor hydrophilic ink must be carried out; Use of special protective plastic; glue can not be too thick; To clean and dry; drying temperature is set below 60 °C; after the printing plate coating should be prevented from seeing light.

352. What are the causes and solutions to the malfunction of the printing plate and text based on improper preservation?

A: The cause of the malfunction: PS version is stored for a long time or improper storage conditions, use exposed for a long time, use blue-violet light as a work light source for printing; after drying, the printing plate is stored for a long time, the storage temperature is high, the storage process sees light, without baking The PS plate processed by the plate is irradiated with strong light.
Solution: PS version should not be stored for more than six months, should be stored at low temperature and light and dry; shorten the loading time or avoid direct light irradiation; yellow light source should be used as the printing plate lighting; the printing plate should be used with the sun; not in high temperature and humidity The plate is stored under conditions; plates cannot be stored under strong light.

353. What are the causes and solutions to the failure of the printing plate before printing?

A: Cause of malfunction: Exposure, runout before development, lack of original density, over development (excessive development time, high development temperature, excessive developer concentration, excessive amount of replenishes, etc.); agent adhesion (strong acids, strong bases, organic solvents) , In addition to dirty fluid, etc.); use PS version cleaner to wipe too many times.
Solution: Save the PS version; save under a yellow security light; re-create the original to meet the density requirements; develop under standard conditions; be cautious with corrosive drugs; reduce the number of PS plate cleaner wipes and so on.

354. What is proofing?
Answer: The work of imminent printing plates installed on the proofing machine for proof printing is called proofing. Proofing is the process of copying and proofing from the graphic information of the group. It is an important procedure for checking the quality of the plate in the printing process and is of great significance in production and management.

355. Why proofing?
Answer: The basic task of proofing is to produce proofs of acceptable quality, provide proofreading results for reviewers, plate makers, and printers. At the same time, in some special cases, it can be done by proofing instead of printing, or in small quantities directly. Print production tasks.
The role of proofing: 1 Check the quality of the printing plate and provide the characteristic parameters for the plate making process. Checking the layout specification, graphic content, overprint performance, etc. of the printing plate through proofing proofs, checking whether the color, level, etc. of the proofs meet the quality requirements, and providing the field density values ​​of the subsequent working procedures for the plate making process, such as machine calibration and process design. Characteristic parameters such as gray balance value and dot gain value; 2 analog printing for editors used for proofreading and validation for customers' printing; 3 standard proofs for printing process; printing process according to proofs for material preparation and machine adjustment as product Quality reference standard.

356. What are the basic features that proofs must have?
A: Since the proofs are the style standards of prints, it must have the following two basic characteristics: First, high-quality demonstration features that can best reflect the various performance characteristics of printing, compared with printing, the requirements of proofing Strict and higher; the second is the feasible production characteristics, that is, it can be mass produced under the existing objective conditions of the factory.

- From "Printing Technology"