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PLATE CARE POINTS

CONDITION

CAUSE

CURE

Weak Image

(On Plate or Press)

  1. Too much water, or not enough ink.
  2. Improperly made plate eg. Incorrect exposure setting improper development, wrong chemicals used.
  3. Glazed ink rollers

  4. Insufficient pressure between plate cylinder and blanket cylinder.
  5. Insufficient pressure between blanket cylinder and impression cylinder.
  6. Gum not fully washed from plate surface.

  1. Read just ink/water balance using Fountain Solution
  2. Remake plate

  3. Clean and deglaze ink rollers (Regular use of Multiwash minimizes glaze)
  4. Adjust to increase pressure.

  5. Adjust to increase pressure.

  6. Remove all traces of plate gum with warm water or plate conditioner.

 

Streaks (horizontally across plate cylinder).

  1. Ink or moisture form rollers set unevenly or too heavy, causing skidding or bouncing on plate.
  2. Improper packing under blanket.

  1. Read just roller pressures and alignment to maker’s specifications.

  2. Repack blanket according to press manufacturer’s instructions

Dark Image or Background Tone

  1. Insufficient moisture being run on press.
  2. Too much ink.
  3. Moisture rollers dirty

  1. Move Fountain Solution control to increase moisture flow.
  2. Reduce amount of ink being run.
  3. Clean Rollers using Cleaner – D

Plate Image Wear Excessive

  1. Ink or moisture form roller pressures too heavy.
  2. Fountain Solution too acid.
  3. Plate to Blanket pressure too heavy.
  4. Improperly developed plate.
  5. Plate under exposed.

  1. Readjust roller pressures to maker’s specification.
  2. Use a pH tester to test fountain solution.
  3. Readjust pressure to maker’s specifications.
  4. Remake plate with proper development.
  5. Remake plate with proper exposure

Scumming (ink appearing in non – image areas.)

  1. Incorrect ink/water balance. (Too much ink or not enough moisture.)
  2. Incorrect fountain solution pH.
  3. Dirty moisture forms roller cover.
  4. Paper coating is not of right quality. (Poor water resistance of coating.)
  5. Incorrect plate processing.
  6. Improperly desensitised plate

  1. Readjust ink/water balance using fountain solution.

  2. Adjust fountain solution pH to read between 5.0 to 6.0.
  3. Clean cover using Cleaner D or fit new one, if necessary.
  4. Use paper with different quality coating.( Use only paper made for offset printing.)

  5. Remake plate using correct chemicals prescribed for plate.

Remake plate follow directions carefully for desensitising plate surface or use plate conditioner.

Plugging) filling in or bridging of halftones, fine reverses etc.)

  1. Too much ink being run.
  2. Plate to blanket pressure too heavy.
  3. Improperly developed plate.
  4. Plate overexposed.
  5. Plates made using exhausted chemicals. (Deteriorated stock.)

  1. Reduce ink flow.
  2. Readjust pressure to maker’s specifications.
  3. Remake plate with proper development.
  4. Remake plate with proper exposure.
  5. Remake plate using fresh chemicals

Hickles and picking (defects in printed iamge caused by dried ink, dirt or paper fibres on plate or blanket).

  1. Worn or cracked ink rollers deposit dried ink particles on to plate.
  2. Dirt or dust on paper.
  3. Dirt on Plate
  4. Weak paper surface.
  5. Ink too tacky.

  1. Remove rollers and clean thoroughly with wash. Fit new rollers, if necessary.
  2. Wipe slitter dust from edges of paper pile fan paper thoroughly.
  3. Clean paper surface.
  4. Use paper with stronger surface.
  5. Reduce tack of ink

Blind plate image (Image does not accept ink.)

  1. Wrong plate gum used when making plate.
  2. Gum film on plate too heavy.
  3.  

  4. Glazed ink rollers.
  5. Contaminated chemicals used during plate processing.

  1. Use correct gum.( preserving gum solution)
  2. Remove all traces of gum using warm water, when preserving plates, use a small amount of gum polish to think dry film.
  3. Clean and deglaze ink rollers.
  4. Remake plate using new chemicals.