Category Archives: Sheetfed Inks

Misting or Slinging

Roller train is too hot

Form roller temperatures should be 72°-80°F (22°-26°C). Higher temperatures will lower the tack and viscosity of the ink, lower temperatures will increase the body of the ink

Ink/water setting is out of balance

Check chemistry for pH, conductivity, Brix level and temperature. Adjust settings to run minimum amounts of ink and water

Too much ink is being carried in an effort to achieve the desired density

If possible, substitute a stronger ink to reduce the ink film thickness on the rollers or run as a double hit

Rollers are worn or improperly set

Check rollers for damage and settings

Ink tack is too low

If possible, increase tack to maximum allowable for substrate being printed. Consult your ink supplier

Metering Roller Build-up

Fountain solution circulation system is contaminated

Drain, clean, flush, replace filters and refill with fresh fountain solution. Desensitize rollers

Fountain solution mix is improper

Check pH, conductivity, Brix level and temperature. Ensure pan temperature is no higher than 65°F (18°C)

Automatic dosing systems are faulty

Check to make sure that doser is dispensing desired levels of chemistry (perform a “jug test”).

Rollers are set improperly

Check settings and the skew of the metering roller and reset to manufacturer specifications

Roller durometer is wrong

Replace rollers with recommended durometer

Pan roller is greasy or contaminated

Clean and desensitize the chrome roller with a good chrome roller cleaner and follow up with a hot water / white vinegar (2:1) wash-up

Inappropriate solvents/washes used to clean metering rollers

Be sure to use metering roller cleaner (MRC)

Linting and Picking

Stock has insufficient lint or pick resistance

Change stock, try a different run of paper

Blanket is improperly packed

Correct packing (underpacking and overpacking causes picking)

Blanket is too tacky

Treat blanket surface to reduce tack. Use blankets with good release properties

Impression is improperly set for the ink/stock combination

Set impression to press manufacturer’s specifications

Ink is too tacky for the stock being run

Reduce tack only enough to eliminate the problem

Ink and water are out of balance

Correct ink/water balance

Ink film thickness is too low

Weaken the ink slightly to improve release from blankets

Hickeys

Foreign particles are adhering to the plate or blanket

  1. Check for contamination in ink and/or fountain solution and rollers for deterioration
  2. Use scotch tape to remove hickey for examination. If pigment or ink skin, remove old ink from fountain and replenish with ink from a freshly opened can
  3. If paper fibers, try a different run of paper or if necessary, gradually reduce the tack of ink

Ghosting – Mechanical

Roller settings are faulty. Rollers are poor or incorrect diameter

Check roller settings and diameter especially form rollers to the plate

Layout of work may be poor

Whenever possible, make take-off bars to compen-sate for lack of ink needs

Ink is too transparent

More opaque inks can sometimes help mask ghosting caused by job layout – consult with your inkmaker

Embossed blanket

Deglaze or replace blanket as indicated

Ink strength

A weaker ink can provide more transfer to even out the ink film

Slow Drying and Slow Setting

Paper pH

Paper should be between a pH of 6.0 and 8.0 Readings lower or higher than this range will affect ink drying

Paper absorption

A paper with low absorption will prevent the inks from setting up, and will slow down the overall drying of the ink film

Fountain solution

High acidity levels will retard the oxidation as will high levels of alcohol substitutes

Paper absorption

Lower the absorption. Slow the setting

Lifts are stacked too high

Run shorter lifts on heavier coverage jobs and ensure spray powder is dispensing correctly and is the correct particle size

Water levels too high and emulsifying the ink

Adjust ink/water balance to lowest levels

Dot Gain

Plate curves may need to be verifed

Have prepress adjust plate curves if necessary and consider GRACoL®/G7* certifcation

Check that the Fountain solution is fresh and within specification

If needed, adjust chemistry to manufacturer’s recommendation

Fountain solution temperature may be too warm

Adjust fountain solution temperature in pans to proper temperature

Ink form rollers may be too warm

If necessary, adjust form rollers to recommended temperatures

Blankets may be packed improperly or too much pressure exists

Check packing and pressures

Slurring or doubling appears in halftones – often confused with dot gain

Check cylinder pressures, blanket tension, and roller slippage. Check mechanical operation of unit

Rollers or blankets are too soft or not set correctly

Condition or replace rollers and blankets and set to manufacturer’s specification

Ink is low in tack / viscosity

Consult your ink supplier for alternative inks

Plate Blinding or Wear

Faulty or improperly set ink or dampening rollers are wearing the plate

Check rollers for condition and settings

Foreign particles are entering into the ink train

Check paper, ink, solutions and overhead structures for foreign materials that may be dropping onto press

Plate cleaners or scratch removers have not been completely rinsed from the plate

Avoid excessive amounts of plate cleaner and scratch remover. Rinse plates thoroughly afterwards Be sure all water, sponges, rags, etc., that come in contact with the plate are clean. Do not let cleaners dry on the plate

Blanket is over-packed or loose

Check packing or blanket tension. Set to manufacturer’s specifications

Fountain solution may be out of balance

Check pH, conductivity, Brix level, and temperature. Ensure pan temperature is close to 65°F (18°C) and solvent level is not too high

Stock is depositing filler, coating, or lint on the blanket affecting plates

Review dampening settings. Check pH and conductivity. Discuss alternatives with your paper supplier

Excessive calcium, gum and other material in roller train

Apply a calcium rinse or hot water/white vinegar (2:1) rinse

Plate has been improperly prepared

Review procedures for plate making process

Backtrapping / Contamination

Heavy ink films/densities in prior units are increasing the opportunity for poor trapping

Lower densities of prior colors and increase density of latter units or change rotation. Lower the tack of the ink if necessary with 2-5% gelled reducer

Paper may have high hold out (low absorption)

This prevents the inks from setting into the paper and tacking up between units leading to poor trapping and tacking up between units leading to poor trapping

Blankets are not releasing ink well

Check blanket compatibility with ink system. Change blanket

Backing Away / Low Flow

Ink fountain ball is too cold

Confirm that ink fountain ball is above 70°F(21°C) to ensure adequate ink flow

Ink fountain is at a low level

Add ink to fountain ball. Added weight will allow ink to follow fountain ball better

Ink is thixotropic and gels

Work ink in fountain frequently, use ink agitators, or add a small amount of overprint vanish to induce flow