Graphic Design & Printing Technology

Graphic Design & Printing Technology

Remedies:- Clean and replace rollers, adjust balance of ink and fountain
solution, replace blanket

Mis-registration

Two overprinted images or colour elements do not align when printed. Major
causes are:

• Excess ink tack


• Curled or wrinkled paper stock


• Printing pressure stretch paper stock


• Image improperly positioned on plate


• Plate mounted improperly


• Loose blanket
  Remedies:- Reduce tack, humidity of pressroom, adjust cylinder pressure,
  remake plate with image in register, reposition plate on plate cylinder, reattach
  blanket
  Mottling

Uneven amount of ink in the solid portion of the image causing printed sheets
to appear cloudy. Major causes are:

• Failure of ink to be absorbed unformly by paper.


• Excess fountain solution.


• Ink not resistant to water.
  Remedies:- Formulate ink to the grade of paper, adjust ink water balance, add
  varnish to increase tack.
  Plateware

It is the gradual disapearance of the image areas from the plate surface. Major
causes are:

• Excess form roller pressure.


• Excess pressure between plate and blanket.


• Fountain solution too acidic.


• Insufficient amount of ink.


• Dried gum on the plate.
  Remedies:- Check for roller pressure, pressure by inking plate, check pH of
  fountain solution, clean the plate with water and solvents, clean blanket.
  Scum

Buildup of ink film on non image areas of the plate. Causes are:

• Too soft ink.


• Excess use of ink.


• Sensitized non image areas of plate.