All posts by sterryInk

Work Piling

Ink becomes waterlogged.  This causes the pigment to separate due to insufficient viscosity and tack

Run less fountain solution on press.  Have ink checked for emulsification characteristics

Rollers are wrong durometer; rollers are improperly set; blanket is underpacked or badly conditioned

Use proper rollers and blankets; check roller settings and blanket packing, or clean and condition

Ink has improper dispersion or grind

Check ink dispersion.  Check ink viscosity.  Consult your Sun Chemical representative

Ink is unstable

Consult your Sun Chemical representative

Fountain solution pH and/or conductivity is incorrect

Check and adjust to supplier recommendations

Ink roller train surface temperatures are incorrect

Adjust roller surface temperatures to recommended values.  Check roller settings

Ink lacks sufficient lubrication or is unstable

Consult your Sun Chemical representative

Dry ink that has not fully transferred from the blanket to the paper can begin to build up, producing a relief image.  This is caused by inadequate blanket cylinder pressure and/or plate or blanket packing

Check blanket cylinder pressure and/or plate and blanket packing

Tinting

Fountain solution has wrong pH or conductivity

Adjust pH/conductivity to manufacturer’s specifications.  Consult a Sun Chemical representative

Roller durometer or setting is wrong

Use proper roller and check setting

Prolonged use of a detergent wash has occured

Wash-up thoroughly and use hot water for final wash-up

Too much pressure exists between plate and blanket

Check and reset

Paper coatings and fountain solution are contaminating and glazing the ink train rollers

Use lowest tack ink possible, and properly balanced dampening solution

Plates are improperly exposed and developed

Consult your pre-press department

Ink is improperly formulated

Consult a Sun Chemical representative

Detergent is present in fountain solution

Eliminate detergent

Temperatures are too high in fountain solution pan and/or ink vibrator roll

Adjust to recommended temperature range

Scumming

Ink rollers are of the wrong durometer (too soft  or too hard)

Check durometer, setting and condition of ink rollers

Ink or dampener rollers are set too tight

Check and reset rollers

Blanket is overpacked or not tight

Correct packing and retorque blanket

Prolonged use of oily wash-up solutions has occurred

Consult your pre-press department

Fountain solution is out of balance

Adjust pH and conductivity

Dampening system is improperly maintained

Conduct proper maintenance.  Refer to Sun Chemical recommended procedures for cleaning and maintenance of fountain solution tanks and press pans

Emulsification characteristics of the ink formulation are incorrect for fountain solution

Consult a Sun Chemical representative

Fountain solution formulation is not correct for ink formulation

Consult a Sun Chemical representative

Ink film is too heavy

Change to a stronger ink and/or consult a Sun Chemical representative

Blanket is glazed

Remove glaze or change blanket

Roller Stripping

Roller surface is glazed or coated

Wash rollers with appropriate solultions and hot water

Fountain solution pH/conductivity is too acidic

Check pH/conductivity settings and correct.  (Adjust to manufacturer’s specifications.)  Clean and sensi-tize rollers with recommended solutions.  Consult a Sun Chemical representative

Poor Trapping

Ink tacks out of sequence

Make sure inks are of proper successively decreasing tack.  In some situations, when a K, C, M, K rotation is used, the black ink may be lower in tack so as to eliminate or minimize picking

Ink strengths are improperly balanced.  This can result in running one color heavy and the following color light, in which case the second or light color may not trap

Reduce strength of ink if it is running too light and carry a heavier ink film. Consult a Sun Chemical representative

Ink/water is not in balance

Achieve and maintain proper ink/water balance.  Running a minimum amount of ink and water is the preferable procedure

Previous ink film is too heavy.  If possible, previous colors should never run heavier than succeeding colors

Run a thinner film, increasing ink strength accord-ingly.  Be aware that, if not done properly, this may cause balance problems as indicated

Ink contains too much slip agent or other additives. Subsequent layers of ink may refuse to trap properly

Consult a Sun Chemical representative

Ink stability curves out of balance

Consult a Sun Chemical representative

Poor Rub or Scuff Resistance

Scuffing is visible at delivery

Refer to inadequate drying section

Ink is improperly formulated

Consult your Sun Chemical representative

Chalking; ink is not binding to stock

Pigment to binder ratio in ink is not compatible with stock.  Consult your Sun Chemical representative

Poor Roller Transfer and/or Glazing

Rollers are improperly or inadequately cleaned

Thoroughly clean-up with a good quality roller glaze remover.  (To remove glaze apply hot water to roll-ers after removing ink.  This will remove gum glaze that is not soluble in standard wash-up solvents)

Rollers are improperly set; rollers are swollen or distorted

Check and adjust roller settings.  Check roller surface conditions

Ink is unstable

Consult your Sun Chemical representative

Gum arabic and gum substitutes are in fountain solution; wetting agents used indiscriminately

Control use of additives and use proven fountain solution

Roller surfaces have calcium build-up on them

Consult your Sun Chemical representative

Plate Blinding or Wear

Plate has been improperly prepared

Review procedures for platemaking process

Surfactant has contaminated the dampening system

Make sure all parts of the dampening system that come in contact with detergent are thoroughly rinsed before being reinstalled on the press

Fountain solution is poorly balanced or improperly formulated

Check pH and conductivity of fountain solution.  Consult your Sun Chemical representative

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

Avoid using excessive amounts of plate cleaner or 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 plate cleaners dry on the plate

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

Use a more lubricated ink.  Review dampening setting.  Check pH and conductivity.  Discuss alternatives with your paper supplier.  Consult your Sun Chemical representative

Faulty or improperly set ink or dampening rollers are wearing plates

Check rollers for condition and settings

Ink is not properly formulated

Consult your Sun Chemical representative

Blanket is overpacked or loose

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

Foreign particles are entering the ink train

Check materials such as paper, ink, and wash-up solution.  Check overhead structure for foreign materials that may be dropping onto press

Vanishing dot occurs in image area due to a non-image area build-up on the plate and blanket surrounding the dot

Use a more lubricated ink.  Increase blanket  washing interval. Consult your Sun Chemical  representative

Misting or Slinging

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

Substitute a stronger ink and run a thinner ink film on rollers

Rollers are worn or improperly set

Check rollers for damage; also check roller settings (check for extreme temperature build-up on rollers)

Roller train is affected by static electricity

Check to ensure press is properly grounded

Ink/water setting is out of balance

Adjust settings

Viscosity of the ink is too low

Consult your Sun Chemical representative

Web is running narrower than press width

Use mourning bands on plate.  Refer to Sun  Chemical mourning band technical notes

Ink “globs” are being thrown onto the web

Adjust ink/water balance.  Use mourning bands.  Refer to Sun Chemical mourning band technical notes

Linting and Picking

Ink is too tacky for the stock being run

Replace with a lower tack ink

Stock has insufficient lint or pick resistance

Change paper.  Consult paper supplier.  Install a brush or vacuum type paper cleaner

Impression is improperly set for ink/stock combination

Set impression to manufacturer’s specifications

Ink/water balance is improper

Adjust ink/water balance

Blanket is too tacky

Treat blanket surface to reduce tack.  Change to a quick release blanket.  Check blanket wash solution.  Consult your blanket supplier

Blanket is improperly packed

Correct packing (under packing as well as over packing causes picking)

Ink formulation is too strong, forcing a thin ink film to be run

Use a weaker ink.  Consult your Sun Chemical  representative

Ink is unstable

Use a more stable, lubricated ink formulation.  Consult your Sun Chemical representative