Scumming

Fountain solution does not have the ability to clean the non-image areas of the plate.

CAUSE CURE
Low alcohol sub concentrate Increase Alc. Sub to correct concentration. Increase if problem persists.
Glazed Rollers Remove and deglazed effected roller. Replace and reset ink stripes.
Excessive pressures. Ink forms to plate Reset to press manufacturers specs.
Plate sensitivity Consult with plate room.
Ink/Water balance Refer to ink/water balance.
Fountain Solution ratio is incorrect Check pH and conductivity for proper mix. Correct as necessary to manufactures recommended dosage.
Central Mix system inconsistent Check proportioner is mixing at correct and consistent ratios. If using a water treatment R.O., D.I. etc. is producing correctly.
Fountain Solution Temp is to high Adjust chilling unit on recirculating tank to chill between 58° to 65° F.
Ink vibrators to hot Increase chill water flow to read between 80° to 85°F.
Roller settings and durometer out of spec Check durometer and settings. Replace and calibrate as necessary.