Offset Printing Blanket Troubleshooting

Action

Can Cause

Remedy

Improper Packing

  • Half tone, graininess or mottle
  • Increase or decrease packing .001” thou at a time

Insufficient Packing

  • Low spot (shows as a non-printing area)
  • Snow-flaky solids
  • Blanket piling
  • Moire pattern or doubling
  • Increase packing
  • Increase packing .001” thou at a time
  • Increase packing .001” thou at a time
  • Pack correctly

Excessive Packing

  • Embossing
  • Ink Film scum
  • Gear marks & streaks
  • Plate wear
  • Decrease packing .001” thou at a time
  • Decrease packing .001” thou at a time
  • Decrease packing .001” thou at a time
  • Decrease packing .001” thou at a time

Improper Impression

  • Half tone graininess or mottle
  • Increase or decrease impression

Insufficient Impression

  • Low spot (shows a non-printing area)
  • Snow-flaky solids
  • Blanket piling
  • Increase impression
  • Increase impression
  • Increase impression

Excessive Impression

  • Slurring-increase of image in vertical direction
  • Fill-in–increase of image in all directions,especially in reversals
  • Embossing
  • Ink film scum
  • Sheet curl & tail end hook(called web trailing on web)
  • Sheets sticking to blanket
  • Reduce impression
  • Reduce impression
  • Reduce impression
  • Reduce impression
  • Reduce impression
  • Reduce impression

Excessive Squeeze Pressure

  • Slurring–increase of image in vertical direction
  • Fill-in-increase of images in all directions,especially in reversals
  • Reduce packing .001” thou at a time
  • Reduce packing .001” thou at a time

Uneven Blanket Cylinder

  • Low spot (shows on non-printing area)
  • Check cylinder

Cylinder Circumference Not Equal

  • Poor register
  • Adjust packing so that each cylinder has equal circumference

Build-up on Back Cylinder

  • Low spot (shows as non-printing area)
  • Clean back cylinder

Press Speed Too Slow

  • Slurring–increase of image in vertical direction
  • Increase press speed

Sheets Pulling off Gripper

  • Sheets sticking to blanket
  • Check grippers

Excessive Ink

  • Slurring–increase of image in vertical direction
  • Reduce amount of ink

Insufficient Ink

  • Snow-flaky solids
  • Increase amount of ink

Excessive Ink Tack

  • Embossing
  • Sheet curl & tail end hook
  • Sheets sticking to blanket
  • Reduce ink tack
  • Reduce ink tack
  • Reduce ink tack

Insufficient Ink Tack

  • Slurring–increase of image in vertical direction
  • Reduce ink tack

Ink Build-up Outside Web or Sheet Area

  • Delamination of edges
  • Cut packing back to within ½ “of image area Also keep blanket clean

Insufficient Alcohol in Fountain

  • Slurring–increase of image in vertical direction
  • Blanket piling (linting on newsprint)
  • Increase Alcohol
  • Increase Alcohol

Excess Water

  • Snow-flaky solids
  • Decrease water

Poor Paper

  • Blanket piling
  • Change paper

Wavy or Tight Edged Paper

  • Slurring–increase of image in vertical direction
  • Change paper

Too Strong Blanket Wash

  • Sheets sticking to blanket
  • Use lower K.B. solvent, preferably water miscible

Loose Blanket

  • Slurring–increase of image in vertical direction
  • Half tone graininess or mottle
  • Moire pattern or doublingn
  • Poor register
  • Tighten blanket
  • Tighten blanket
  • Tighten blanket
  • Tighten blanket

Blanket not square

  • Slurring–increase of image in vertical direction
  • Poor register
  • Use square blanket
  • Use square blanket

Blanket too firm

  • Slurring–increase of image in vertical direction
  • Use compressible blanket

New Blanket

  • Blanket piling (linting on newsprint)
  • Blanket has to be broken-in

Glazed Blanket

  • low spot–shows as non-printing area
  • Clean blanket

Non-Thiokol Surface Blanket

  • Sheets sticking to blanket
  • Use Thiokol surface blanket

Non-Release Blanket

  • Sheet curl & tail hook (called web trailing on web)
  • Use release blanket

Blanket Carries too much Ink

  • Half tone graininess or mottle
  • Use sharper printing blanket

Non-Compressible Blanket (Conventional)

  • Gear marks & streaks
  • Plate wear
  • Use compressible blanket
  • Use compressible blanket

Compressible Blanket

  • Snow-flaky solids
  • Use conventional blanket (sheetfed or increase Packing)

Porous Blanket Surface

  • Snow-flaky solids
  • Change blanket

Blanket Swelling

  • Slurring-increase of image in vertical direction
  • Fill-in-Increase of image in all directions especially in reversals
  • Use solvent resistant (Thiokol), blanket wash or lower KB solvent
  • Use solvent resistant (Thiokol), blanket wash or lower K solvent

Blanket prints too full

  • Fill in–increase of image in all directions,especially in reversals
  • Use sharper printing blanket

Swelling of Blanket fabric

  • Delamination of edges
  • Seal edges- keep solvents from getting underneath blanket

Blanket surface too spongey

  • Poor register
  • Use blanket with firm surface

Blanket becomes tacky

  • Sheets sticking to blanket
  • Powder blanket with chalk or spray powder (blanket hard)

Piling on Blanket

  • Fill-in–increase of image in all directions especially in reversals
  • Clean the blanket