. variablesi

PRODUCTION VARIABLES (I)

"Good printing means controlling an array of production variables more complex than anything known to most other kinds of manufacturing."

• Paper is always a question mark.

• There can be defects and
inconsistencies in sheet and roll stock (e.g., flaws that cause web breaks).

• Humidity, temperature, and dirt can reduce the "runnability" paper.

• The "weather" in the pressroom could be different from the "weather" where the paper was stored. Sheet edges become wavy or tight as moisture is absorbed or lost at press-side. This can threaten registration. Paper should always be "conditioned" before running.

• Every litho press run is still a chemistry experiment.

• Ink and fountain problems: scratch-off or rub-off from poor mixing... "scumming," i.e., adhesion in non-image areas... "emulsification" turns ink to sludge when the pH of the fountain solution is too acidic...algae in the water: yuck!

• Plates can fracture or become scratched; blankets get "smashed."

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