Troubleshooting





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Troubleshooting
Incidents
 
  1. Picking
  2. Deformation in the stack
  3. Double print
    Abnormal pressure force and dots blurred.
  4. Binding of the plate
    Deterioration of the printing areas and/or graining areas (non- printing areas).
  5. Scumming Blocking
  6. Out of register prints
  7. Set-off
  8. Incorrect drying
  9. Hickies
  10. Creasing
    Deformation of the substrate, mainly at the tail end.
  11. Powdering
    The ink solids remain on the surface.

  12. Poor trapping
    Ability of one ink to be accepted by another when it is not yet dry (this phenomenon only applies to wet-on-wet printing).
  13. Curling
    Excessive deformation of the printed material in the stack (excessive curling beyond 4cm/m).

  14. Mottling
    Irregular appearance (mainly on solid print areas).
  15. Linting
    Loose paper accumulated on the blanket.


  16. Piling / Buildup
    Ink build up on image areas of the blanket
  17. Guttering
  18. Phantom effect
    Reappearance of the previous print run or the print run underway but out of shift.

Probable causes and remedies
 
 1. Picking (back to incidents)
 
Cause 
Paper too fragile (poor coating or poor structure).
Remedie
Change the paper, dilute the ink or use a more suitable ink (less tack). Add Anti Tack Compound (3 % max.) or Arctic Thinner 501 (3% max.).
Cause 
Restarting after a prolonged press stoppage.
Remedie
Spray Rototack start-up aerosol over the rollers.
Apply a little thinner (Artic Thinner 501) onto the rollers.
Clean the rollers.
Clean the blankets.
Cause
Print shop temperature too low.
Remedie
Dilute the ink before restarting printing. .
   
   
Cause
Excessive dampening.
Remedie
Reduce the dampening.
Cause
Excessive blanket / paper pressure.
Remedie
Check the blanket / cylinder pressure, the counter pressure and the cylinder coverings.
Cause
Blanket has too much “affinity” for the ink.
Remedie
Apply talc on the blankets.
 
2. Deformation in the stack (back to incidents)
 
Cause
Substrate stored incorrectly.
Remedie
Before printing: store in the original packaging at a temperature of around 20°C and a relative humidity of 60 %, for a period determined by the temperature in relation to the volume of the stack.

During printing: between runs, do not hesitate to cover pallets to avoid deformation phenomena.
Cause
Excess or irregular use of anti set-off powder.
Remedie
Adapt the quantity of anti set-off powder and its particle size to the job in hand. Clean the powder spray nozzles.
Cause
Excess water, principally on the paper edges.
Remedie
Reduce or adjust the uniformity of the dampening.
 
3. Double print, abnormal pressure force and dots blurred.
(back to incidents)
 
Cause
Substrate deformed before printing.
Remedie
Change the substrate.

Avoid important relative humidity and temperature variations between the storage and printing areas. Place the paper in the print shop several hours before printing.
Cause
Blanket not tight enough.
Remedie
Retighten the blanket.
Cause
Excess pressure.
Remedie
Check the cylinder coverings.
Cause
Slack impression cylinder or transfer cylinder clips.
Remedie
Adjust the clips (wear on the heels of the clips).
Cause
Tack of the ink too high.
Remedie
Add Anti Tack Compound (3% max.) or Arctic Thinner 501 (3% max.) to the ink.
 
4. Binding of the plate, deterioration of the printing areas and/or graining areas (non- printing areas).
(back to incidents)

Cause
Abrasive particles from the paper coating deposited on the blankets.
Remedie
Pre-lacquer the substrate. If possible, place the first group under pressure only with the dampening.
Cause
Pre-sensitised plate exposed too long to light.
Remedie
Rework the plate. Protect the plate during print runs and apply gum during press stoppages.
Cause
Quality of the plate unsuited to the length of the print run.
Remedie
Properly oven treat the plates.
Cause
Form rollers incorrectly adjusted (pressure too high).
Remedie
Adjust the roller settings.
Cause
Excess plate cylinder / blanket cylinder pressure.
Remedie
Adjust the pressures. Check the cylinder coverings.
Cause
Excessive hardness of rollers.
Remedie
Deglaze the rollers with Roline Arctic Deglazer or change them.
Cause
Abnormal movement of form rollers (with certain presses, equipped with form roller movement, it is recommended to use special high quality or oven treated plates).
Remedie
Change the bushes or rollers.
Cause
Abusive use of hicky removal systems (delta effect).
Remedie
Use the system sparingly (less than 1 minute).
Cause
Water too acid.
Remedie
Adjust the pH to obtain a fount solution within the norms.
Cause
Water too hard.
Remedie
Check the water hardness.
 
5. Scumming, blocking (back to incidents)
 
Cause
Paper surfacing or coating fragile. Incorrect ratio between surface tension of fount solution / surface energy of plate
(ST < SE).
Remedie
Improve the transfer of the fount solution by checking its dosage and, if necessary, add a transfer improving agent. Rework the plate.
Cause
Paper too alkaline.
Remedie
Readjust the water / ink balance.
Cause
 Oxidation of the plate due to insufficient or incorrect gumming.
Remedie
Clean the plate with a de-oxidising solution followed by light gumming.
Cause
Dampeners clogged up.
Remedie
 Check / clean the dampening rollers and the dosing units.
Cause
Partial swelling of the blanket due to excessive use of deglazer.
Remedie
Change the blanket.
Cause
Temperature too high in the inking rollers (ink becomesmore fluid).
Remedie
Reduce the temperature and the print speed, change the ink and restart the print run.
Cause
Excessive inking.
Remedie
Reduce inking. Use an ink with higher colour strength.
Cause
Tack of the ink too low.
Remedie
Use a more tacky ink.
Cause
Ink too diluted.
Remedie
Open a new tin of ink.
Cause    
 Ink too siccative.
Remedie
Use a less siccative ink.
 
6. Out of register prints (back to incidents)
 
Cause
Poor dimensional stability of the paper (paper fibre in wrong direction) and excess water.
Remedie
Always print the substrate with the paper fibres parallel to the cylinders.
Cause
Blanket tension incorrect.
Remedie
Retighten.
Cause
Unsuitable cylinder coverings.
Remedie
Adapt the cylinder coverings to rectify them if possible.
Cause
Clips loose due to incorrect adjustment and / or tacky ink.
Remedie
Adjust the clips.
Cause
Paper deformed after several print runs and / or high inking level.
Remedie
Reduce inking.
 
 
Cause
Optical Density too high, out of standard.
Remedie
Print using the Brunner standard, for example, or print using two printing units. Reduce inking.
Cause
Poor ink distribution.
Remedie
Adjust the form rollers of the printing unit.
Cause
Incorrect Dampening.
Remedie
Adjust the fount solution. > See « The fount solution ».
Cause
Excess water.
Remedie
Adjust the water / ink balance.
Cause
Deformation of the stack due to heavy loads. Stack toohigh.
Remedie
Adapt the height of the stack according to the inking level and paper weight. Do not stack up pallets.
Cause
Not enough anti set-off powder.
Remedie
Adjust the amount of anti set-off powder.
Cause
Particle size of the anti set-off powder not adapted tothe substrate.
Remedie
Adapt the particle size to the weight of the paper / cardboard. Use Arctic Vanesse or Arctic Vanesse 15μm anti set-off powders. Take account of post printing operations (varnishing, laminating).
Cause
IR lamps at incorrect temperature.
Remedie
Adjust the temperature of the IR lamps as a function of the prin- ting speed, substrate grammage and whether printing on both sides. Recommended temperatures:
Top side: maximum 35°C
Reverse side: maximum 30°C.
Cause
Magnetisation of the paper.
Remedie
Use a suitable anti-static system. Properly earth the press. Humidify the print shop.
Cause
Handling of the stack after printing.
Remède
Descend the loader slowly. Handle the stacks carefully.
Cause
Unsuitable ink.
Remedie
Change the ink / substrate. Consult the supplier.
Cause
Ink too emulsified.
Remedie
Wash the printing unit and re-start with minimum dampening.
 
8. Incorrect drying (back to incidents)
 
Cause
Substrate too acid (destabilisation of the water / ink balance).
Remedie
Check the pH of the fount solution. Change the substrate.
Cause
Fount solution too acid.
Remedie
Check and adjust the fount solution > See « The fount solution ».
Cause
Excessive inking.
Remedie
Reduce the amount of inking.
Cause
Excessive dampening.
Remedie
Reduce the amount of dampening. If necessary, clean the inking train so as to completely eliminate the emulsion and restart with less dampening. Check the pressure of the dampening rollers.
Cause
Wrapping or film covering too rapid (air oxidation ofthe ink film insufficient).
Remedie
Allow inks to dry completely before wrapping or covering in film.
Cause
Ink too emulsified.
Remedie
Find the correct ink / water balance.
Cause
Ink does not dry correctly.
Remedie
Add Triple Drying Agent (1 % max. since too much drying agent can inhibit drying).
Cause
Ink not adapted to the substrate
Remedie
Consult the supplier.
 
 
Cause
Poor quality paper (linting, coating lift off).
Remedie
Change the paper or reduce the tack of the ink with Anti Tack Compound (3% max.). Carry out a run without inking.
Cause
Accumulation of ink on the dampeners and / or thedampener form rollers.
Remedie
Wash the dampening rollers. Prevention: replace the first form roller with an anti-hicky roller. If re-guillotining the paper, square it up well, and avoid making a reject cut.
Cause
Ink used from opened or incorrectly protectedcontainers.
Remedie
Protect opened tins correctly with cellophane or by spraying Anti-drying A11 and remove the surface skin.
Cause
Skin on the ink when container opened.
Remedie
Change the container of ink.
 
10. Creasing, deformation of the substrate, mainly at the tail end.
 
Cause
Paper wrapped before printing.Excess paper hygrometry.
Remedie
Check the storage of the paper. Store the paper in the print shop before printing.
Cause
Deformation of the paper on first print run due to toomuch inking or an ink with too high tack.
Remedie
Reduce the tack of the ink during the second print run. Use Anti Tack Compound or Arctic Thinner 501.
Cause
Clips incorrectly adjusted on the margin or wheelsincorrectly adjusted (pressure too high).
Remedie
Adjust the clip settings to regular pressures. Reduce the wheel pressure settings.
Cause
Blanket not sufficiently tight.
Remedie
Retighten the blanket.
 
11. Powdering, the ink solids remain on the surface.
 
Cause
Paper too porous, causing the ink binder to separatefrom the pigment.
Remedie
Apply a primer coat.
Cause
Ink viscosity too low.
Remedie
Use a higher viscosity ink.
Cause
Drying of ink too slow.
Remedie
Use a more siccative ink. Consult the supplier.
Cause
Dampening water too acid, leading to longer dryingtimes.
Remedie
Adjust the fount solution. To mask the phenomenon, apply an overprint varnish.
 
12. Poor trapping, ability of one ink to be accepted by another when it is not yet dry (this phenomenon only applies to wet-on-wet printing).
(back to incidents)

Cause
Unsuitable colour sequence.
Remedie
Adjust the colour sequence: Print low colour deposits before high colour deposits (e.g. Violet = 75 % Red and 100 % Blue ⇒ Print the Red first). In the case of poor trapping, dilute the second colour (e.g. Violet = 100 % Red and 100 % Blue ⇒ Dilute the Blue with a suitable thinner).
 
13. Curling, excessive deformation of the printed material in the stack (excessive curling beyond 4cm/m).
Cause
Problem with the paper.Curling of the sheet parallel or perpendicular to thedirection of the press (central region of the parent roll,foudrinier table, dryer).
Remedie
Change the paper.
Cause
Hygrometry too high or important change in the hygrometry.
Remedie
Check the storage conditions.
Cause
Unsuitable blanket hardness.
Remedie
Use a blanket with a harder surface.
Cause
Excessive dampening.
Remedie
Reduce the dampening.
Cause
Ink too tacky.
Remedie
Reduce the tack with Anti Tack Compound (3 % max.). When printing large solid areas, print a light screen first (base print), which then allows the thickness of the ink film to be reduced on a second print run.
 
14. Mottling, irregular appearance (mainly on solid print areas).
 
Cause
Paper has irregular smoothness.
Remedie
Change the paper. Change the ink.
Cause
Excess dampening, which has the effect of reducingthe tack.
Remedie
Adjust the dampening to the minimum.
Cause
Ink too emulsified.
Remedie
Change the ink.
Cause
Lack of pressure (piling).
Remedie
Adjust the pressure settings.
Cause
Ink from previous prints deposited on the blanket.
Remedie
Dilute the ink of the previous printing units that are being trans- ferred.
 
15. Linting, loose paper accumulated on the blanket. (back to incidents)
 
Cause
Binding or surfacing of the sheet of paper insufficient.
Remedie
Print a solid print area with transparent white ink without dam- pening. Carry out a run without inking. Change the paper.
Cause
New or badly washed blanket that is too adherent.
Remedie
Wash the blanket correctly and apply talc.
Cause
Excessive pressure between the blanket cylinder andthe counter pressure cylinder.
Remedie
Adjust the pressure settings.
Cause
Ink too tacky.
Remedie
Reduce the tack with Anti Tack Compound (3 % max.).
Cause
Non uniform water supply to blanket.
Remedie
Adjust the water meteringspeed settings.
 
16. Piling / buildup, ink build up on image areas of the blanket.
(back to incidents)
 
Cause
Spalling of the paper coating by the fount solution.
Remedie
Change the paper. Slightly increase the dampening.
Cause
pH of the fount solution too acid.
Remedie
Adjust the pH of the fount solution > See « The fount solution ».
Cause
Irregular dampening.
Remedie
Increase the speed of the dampening tank roller.
Cause
Incorrect water / ink balance.
Remedie
Check the water / ink balance. Slightly reduce the alcohol level.
Cause
Ink too sticky.
Remedie
Soften the ink with Arctic Thinner 501 (3 % max.).
 
17. Guttering (back to incidents)
 
Cause
Irregular ink deposition.
Remedie
Incorrect imposition. Check the form roller movement. Adjust the pressure settings.
 
18. Phantom effect, reappearance of the previous print run or the print run underway but out of shift.
Cause
Worn blanket.
Remedie
Change the blanket. Even if the blanket seems to be clean, its compressible layer may be altered and the phantom image may appear later.
Cause
Form rollers incorrectly adjusted on inking rollers.
Remedie
Adjust the pressure settings of the form rollers on the inking rol- lers.



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