The reason and countermeasures of the offset ink rotation fault (2)

Ring white spot:

phenomenon:
A circular core-shaped ring surrounds an ink dot.

the reason:
<1> The impurities in the ink adhere to the plate.
<2> The paper dust is peeled off and stuck on the plate.
<3> Dust particles or other materials on the printing press.

Countermeasures:
<1> Wash plate to remove impurities and replace new ink without impurities.
<1> Washing removes impurities and replaces paper that does not come off paper powder.
<3> Wash plate to remove impurities.

Stacking:

phenomenon:
The ink or ink mixture accumulates on the printing plate and the leather cloth, and the printed text area appears to be partially light or hairy.

the reason:
<1> The ink has poor fluidity after ink emulsification and does not transfer well.
<2> Paper powder or paper wool is mixed with ink and accumulated on the plate.

Countermeasures:
<1> Replace the ink with good water resistance, or add anti-water additives.
<2> Replace paper with low paper dust.

Plate non-graphically dirty:
phenomenon:

Non-graphic areas can be seen on the prints.

the reason:
<1> The ink is not emulsified after being emulsified and emulsified on the plate.
<2> The fountain solution has a large surface tension, and the non-graphic area of ​​the plate is not well inked.
<3> Ink roller and plate pressure are too large.

Countermeasures:
<1> Replace the ink with good water resistance.
<2> Increase the IPA content.
<3> Adjust the ink roller and layout pressure.

Off-page:

phenomenon:
The printing version of the graphic area is poorly inked, and the print density is reduced or the picture is not complete.

the reason:
<1> The plate is not sensitive to grease.
<2> The paper powder that has come off the surface of the paper is worn by the plate surface.
<3> Insufficient printing pressure causes the image film of the plate to be worn off.
<4> Too much pH solution in the fountain solution causes the plate to corrode and the graphic comes off.

Countermeasures:
<1> Replace the new version.
<2> Replace better quality paper and use less viscous ink.
<3> Adjust the pressure, reduce wear.
<4> Pay attention to the adjustment of the fountain solution and add the PH solution at a reasonable ratio.

·Water roller stick ink:

phenomenon:
The ink on the transfer roller of the printing press.

the reason:
<1> The ink is resistant to poor ink emulsification.
<2> Water roller and plate pressure are not normal.

Countermeasures:
<1> Replace the ink with good water resistance.
<2> Adjust the water roller pressure.

Bad overprint:

phenomenon:
After the color sequence ink overprint or not overprint.

the reason:
<1> After the color sequence ink is more viscous than the preceding sequence ink, the previous color ink is pulled off.
<2> After the color sequence, the ink is pulled off before the ink is too large.

Countermeasures:
<1> Change the color sequence or reduce the viscosity of the color ink after the color sequence.
<2> Reduce the color press of the color printer after adjustment.

(to be continued)