TROUBLE SHOOTING

Problem
Cause
Solutions

Fluctuation of Ink & Water Balance

ink and water settings require constant

adjustments during press run

  1. Poor maintenance of unit
  2. Excessive ink emulsification
  3. Improper concentration of fountain solution
  4. Density too high
  1. Check ink form roller settings to plate and drum. Check water form roller setting to plate. Check pickup roller to chrome roller (where aplicable). Check speed settings on water motors. Check conditon of rollers (deglaze if necessary)
  2. Check with ink supplier
  3. Check fountain solution by adjusting to proper pH and conductivity level
  4. Check density with densitometer then reduce density and water to proper aim points



Former Board & Pipe Roller Build-Up

Accumulation of ink and lint on former board and pipe rollers

  1. Improper ink/water balance
  2. Improper concentration of fountain solution
  3. Applying too much ink
  4. Improper maintenance, lack of sufficient cleanup
  5. Improper selection of ink for special stocks
  6. insufficient penetration into newsprint
  1. Adjust to proper ink/water balance
  2. Check fountain solution by adjusting to proper pH and conductivity level
  3. Reduce amount of ink
  4. Clean former board and pipe rollers on a regular basis
  5. Consult your ink supplier
  6. Change to a more absorbent paper



Problem
Cause
Solutions

Grey & Weak Solids

Solids appear weak, lack density

  1. Improper ink/water blance.
  2. Improper concentration of fountain solution
  3. Non-uniform dampening
  4. lack of impression
  5. Los of image area

Note: Additional solutions to correct grey and weak sollids

  1. Adjust to proper ink/water balance
  2. Check fountain solution by asjusting.to proper conductivity
  3. Check condition of brushes, flicker blades, etc., clean or replace
  4. Check blanket height
  5. See : Plate Wear. Check for improperly set form rollers



Misting, Spray or Ink Fly

Excessive amount of ink being thrown from ink train rollers

  1. Carrying too much ink on roller train
  2. Improper roller settings or rollers in poor condition
  3. Improper ink/water balance
  4. Improper fountain solution concentration
  5. Low ink viscosity
  6. Press speed too high for type of ink
  1. Reduce ink density
  2. Reset roller based on manufacturer's specification. Replace if in poor condition
  3. Adjust to proper ink/water balance
  4. Check fountain solution and adjust to proper pH & conductivity
  5. Reformulate
  6. Down the press speed or change with the correct ink



Problem
Cause
Solutions

Linting

Accumulation of paper lint on plates, blankets and/or ink train rollers

  1. Tack of ink too high for type of paper used
  2. Excessive water settings
  3. Improper concentration of fountain solution
  4. Improperly packed cylinder
  5. improper tension controls
  6. Excessive amount of lint on newsprint

Note : Additional solutions to correct linting

  1. Reduce tack of ink
  2. Adjust to lowest possible ink/water balance
  3. Check fountain solution by adjusting to proper pH & conductivity
  4. Check & repack to manufacturer's specification
  5. Check specifications or modify, check rolls
  6. Consult paper manufacturer. On presses with roll stands, reverse the direction of unwind



Mottling

Solid area not uniform in density

  1. Improper ink/water balance
  2. Excessive linting on blanket
  3. Improper blanket to blanket packing or blanket to plate packing
  4. Improperly set form rollers or rollers in poor condition
  5. Uneven dampening distribution
  1. Adjust to proper ink/water balance
  2. Reduce liming condition (see Linting)
  3. Check bearer to bearer packing and manufacturer's specification
  4. Check condition and reset form rollers to manufacturer's specification. Replace of necessary
  5. Check condition of sock rollers, brushes, flicker blades, etc., clean or replace



Problem
Cause
Solutions

Muddy Appearance of Halftones

Halftones lack sharpness in highlight areas

  1. Excessive ink being applied to the plate
  2. Poor materials for good reproduction
  3. Plate improperly processed
  4. Excessive dot gain
  5. Excessive linting
  6. Improper form roller settings
  7. Improper ink/water balance
  1. Reduce ink
  2. Determine reproduction process
  3. Re-check exposure using grey scale (Stouffer scale)
  4. Determine dot gain on press and plate
  5. See Linting
  6. Adjust setting to manufacturer's specification
  7. Adjust to proper ink/water balance. Check for glazed blanket



Set-Off

Ink from printed side of page setting off an adjacent page of finished product

  1. Slow ink drying
  2. Delivery pile too high
  3. Too little spray powder
  4. incorrect side jogger setting in the delivery
  5. Excess static in delivery pile is attracting sheets to each other
  1. See Slow Drying
  2. Reduce height of pile
  3. Increase spray powder
  4. Adjust jogger so sheets do not slide
  5. Use anti static



Problem
Cause
Solutions

Plate Wear

Gradual loss of image, plate scums overall

  1. Dampening rollers set too tight against plate
  2. Excess plate to blanket pressure. May be due to swollen or embossed blanket
  3. Too much acid in fountain solution
  4. Improperly made plate
  1. Reset rollers
  2. Adjust pressure; if blanket is swollen, change
  3. Check pH and adjust to 4.8-5.3
  4. Remake plate



Toning or Scumming

Ink adheres to non-image area & isn't easily removed

  1. Ink too soft
  2. too much ink being carried
  3. Fountain solution pH incorrect
  4. Too much pressure on ink rollers
  5. Abrasive particles picked up from paper surface by blanket
  1. Add high viscosty varnish 15-20%
  2. Carry less ink
  3. Check water fountain & adjust pH to 4.8-5.3
  4. Check roller stripe width on plate and adjust if necessary
  5. Reduce plate-to-blanket & back cylinder pressures, increase water levels or change paper



Problem
Cause
Solutions

Tinting

Ink appears in non-image areas but is easily removed with wet sponge

Note : if ink cannot be easily removed then see Toning

  1. Form rollers set too tight
  2. Fountain solution too acid
  3. Soluble materials in paper coating extracted by fountain solution causing excessive ink emulsification
  4. Alcohol level too high
  1. Re-adjust rollers
  2. Adjust pH to 4.8 - 5.3
  3. Change paper
  4. Reduce alcohol levels in fount



Stripping

Rollers accept ink unevenly

  1. Glazed rollers
  2. Fountain solution too acid, or contains too much gum
  3. Insufficient ink
  4. Dried ink or dirt has built up between blade & fountain roller
  1. Deglaze rubber rollers
  2. Adjust pH to 4.8-5.3 or chenge fount with lower gum content
  3. Run heavier ink film
  4. Keep blade and fountain roller clean at all time



Problem
Cause
Solutions

Slow Drying

Ink film soft and marks easily

  1. Ink levels too high
  2. Ink over-emulsified
  3. pH of paper too low
  4. Cobalt driers added to ink
  1. Cut back amount of ink
  2. Reduce water level
  3. Check pH of paper and change if necessary
  4. Excess drier can retard ink drying



Ghosting (Mechanical)

Fiant image appears in a solid area

  1. Poor ink distribution
  2. Insufficient ink
  3. Solids & type matter poorly laid out on plate
  1. Add low viscosity varnish to improve ink distribution
  2. Increase ink feed
  3. If possible ensure that solids are well distributed on the plate layout



Problem
Cause
Solutions

Picking

Ink ruptures paper surface, picking off small pieces of paper or causing v-shaped tears or delamination of paper coating

  1. Ink too high in tack
  2. Blanket tacky & pulling sheet surface
  3. Insufficient ink on rollers
  4. Press speed too high
  5. Paper weakened by excessive moisture
  1. Reduce ink tack by adding liquid reducer 1-2%
  2. Change to quick-release blanket
  3. Increase ink levels
  4. Reduce press speed
  5. Reduce damp levels to a minimum



Piling

Ink builds up or piles on rollers, plate or blanket & fail to transfer properly

  1. Too much water & ink being carried, causing ink to emulsify
  2. Ink too high in viscosity
  3. Ink is not sufficiently water repellent
  4. Soluble paper coating transferring to blanket & reducing ink transfer
  1. Clean up & re-adjust ink and water setting
  2. Add reducer 2-3%
  3. Add water resistant varnish & reducer water
  4. Reduce water levels, use quick release blanket, reduce press speed



sources :

  • Huber Chemicals
  • Wolstenholme Int'l Ltd