PROBLEM
Drying – The coating will not dry within acceptable limits, even though "nothing" has changed from last run.
CAUSE
  • Dryer failure.
  • The system was likely near its limit without the operator being aware of this threshold.
  • Excessive coat weight.
  • Coating viscosity is too high.
  • High relative humidity.
  • Heavy ink coverage.
  • Excessive moisture content in the stock.
  • Variations in stock absorbency.
SOLUTION
  • Check IR lamps, air movement & exhaust.
  • A faster drying coating might be needed.
    Other adjustments would be:
    a) Boost heat
    b) Increase air flow
    c) Slow the press down
    d) Lower the coat weight
    e) Check the ink density
  • Lower coat weight
    a) With coater settings.
    b) By decreasing viscosity.
  • In the summertime, ambient air has a higher moisture content and therefore less ability to dry. If the pressroom is not climate controlled, boost the heat and airflow or try a faster drying coating.
  • This can be a problem especially with dark colors. A more efficient drying system or coating might be needed. The ink water pick up should also be investigated as this can sometimes be a swing factor. Run stronger ink of possible.
  • Try changing the paper stock first. If the drying problem does not persist with the new stock, check the original stock for moisture content. The ideal range is 5-6%. Higher than that can severely limit absorption, thus adversely affecting drying speed.
To Print: Ctrl+P (PC) or Command+P (Mac)