Offset Printing Blanket Troubleshooting

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