Tackiness of ink & Acidity of Dampening Solution

Tackiness of Ink:

  • High ink tack can make it difficult for the ink to transfer from the ink duct to the rollers, requiring continuous stirring.
  • It can also lead to increased print waste and significant variations in ink density, affecting print quality.
  • High tack might affect ink mileage due to increased key opening and the need to run over the ink density.
  • Severe ink fading can occur, especially when new, high-tack ink lots are running on all towers.
  • Ink being too hard to fetch from the bucket and stir in the ink duct is a common issue with high tack.
  • "Patchy printing" and overall high black ink density can be observed with high ink tack.

Excessive Acidity of Dampening:

  • Scumming

Cause: The excessive acidity eats away at the protective coating on non-image areas of the printing plate, making them susceptible to ink adhesion.

Result: Ink appears on areas where it shouldn't be, leading to a dirty or dirty background.

  • Plate Blinding
Cause: The acid damages the ink-receptive image areas of the plate, preventing ink from adhering properly. 

Result: The print quality suffers, becoming dull or faded, and the plate loses its durability. 

  • Poor Ink Drying
Cause: An overly acidic dampening solution can affect the pH of the ink on the printed material, hindering the oxidative drying process. 

Result: Ink may not dry properly, leading to smudges or dirt on the back of the printed sheets. 

  • Roller Stripping & Blanket Contamination
Cause: Excessive acidity can also affect the dampening rollers and the rubber blanket, impairing their ability to function correctly. 

Result: Ink deposits can form on these components, interfering with the proper transfer of ink and resulting in a buildup of material on the blanket and rollers. 

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