廿 6. Ink thickening
During long-term printing, the printing ink gradually loses fluidity, and the abnormal increase in viscosity causes the printing ink to freeze, and the subsequent use of residual ink is more difficult.
1. When the solvent in the printing ink is volatilized, it will generate dew and mix with the printing ink when it encounters low temperature outside the world (especially it is easy to occur in the unit with small consumption of printing ink).
2. When the printing ink uses a pigment with high affinity for water, the new ink will also thicken abnormally.
1. Quick-drying solvents should be used as much as possible, but sometimes there will still be a small amount of water entering the printing ink at high temperature and humidity. When abnormality occurs, new ink should be replenished or replaced in time. Residual ink that is used repeatedly should be filtered or discarded regularly because of the moisture and dust involved.
2. Discuss the thickening abnormalities with the ink manufacturer, and improve the ink formula if necessary.
VII. Odor (solvent residue)
The organic solvent in the printing ink will be mostly dried instantly in the dryer, but the residual trace solvent will be cured and transferred to the original film and remain. The amount of high-concentration organic solvent residue in the printed matter directly determines the odor of the final product. Whether it is abnormal can be judged by nose smell. Of course, with the advancement of science and technology, relying on the nose to smell has obviously fallen behind. For items requiring higher solvent residues, they can be measured with the help of professional instruments.
Printing speed is too fast
2. Inherent properties of resins, additives and adhesives in printing inks
3. The drying efficiency is too low or the drying method is insufficient
5. The air duct is blocked
Reduce the printing speed appropriately
2. The situation of ink residual solvent can be negotiated with the ink manufacturer to prevent it. The use of quick-drying solvents only makes the solvent evaporate quickly, and it does not have a great impact on reducing the solvent residue.
3. Use fast-drying solvents or low-temperature drying (Rapid drying will skin the ink surface and affect the evaporation of internal solvents. Slow drying is effective to reduce the amount of solvent residues.)
4. Because the residue of organic solvents is also related to the type of the original film, the amount of solvent residues varies according to the type of the original film. When appropriate, you can discuss the solvent residue with the original film and ink manufacturers
5. Regularly clean the air duct to make the air flow smoothly
VIII. Mutual solubility
The front-color printing ink dissolves in the rear-color printing ink, causing the intersections, and the edges of the front-color graphics are slightly exposed.
1. After-color printing ink solubility is too good
2. Printing speed is slow
3. Excessive printing pressure
4. Rejection of two inks
Increase the volatilization rate of the first color
2. Properly increase printing speed
3. Appropriately reduce printing pressure (with the principle of no shortage of ink)
4. Adding a small amount of isopropyl alcohol to the post-color printing ink can also solve the mutual dissolving phenomenon, but it should not be excessive, otherwise the post-color printing ink will become tofu brain thick
廿 Nine, ghost
After the printed text is overprinted with a background color or white, a fuzzy shadow from thick to thin appears at the back of each text, just like the tail of Harley's comet.
Scraper angle is too small
2. The plate dot is too shallow
3. Ink viscosity is too low
4. Printing speed is too slow
5. Wear of the ball bearing causes runout
6. Poor ink quality
1. The scraper is retracted properly to increase the scraper angle
2. Remake the plate and deepen the outlets
3. Properly increase viscosity
4. Properly speed up printing
5. Replace pressure
将底色油墨更换新墨、或换别的厂家的油墨试试看（比如黑色文字在底黄处出现重影，则更换黄墨，而不是黑墨） 6. Replace the background ink with a new ink, or try another ink from another manufacturer (for example, if the black text appears as a ghost on the yellow background, replace the yellow ink instead of the black ink)
Thirty, unclear printing
The contrast of the three primary colors is not enough, resulting in insufficient layered sense, insufficient three-dimensional sense, and blurred vision.
Improper color separation before plate making
2. Ink viscosity is too low
3. Three primary colors are polluted
3-1. When the printed dark color passes through the light-colored unit, the ink is slightly precipitated, and the light-colored ink is contaminated due to long-term printing
3-2. The ink tank is too dirty, causing the ink to be contaminated (for example, the original tank containing dark ink is used to hold light ink)
3-3. The back side of the scraper is too dirty, causing ink to be contaminated
2. Properly increase ink viscosity
3. Replace with new ink, use a clean ink tank to hold the ink, and replace it with new paper
It should be pointed out that the above list is part of the common anomalies of gravure printing, but not all of them. And because of different workshop environment (temperature and humidity), working equipment, working conditions, working methods, there will be a variety of different abnormalities, we can solve them through their own work skills.