Real-Time Rates of Water Pickup by Lithographic Inks

Laboratory water-pickup rates are measured in minutes. On-press ink-water contact is measured in milliseconds. This discrepancy was addressed through printing press experiments in which all of the ink was scraped from the return side of the first ink vibrator. For typical newsinks, initial rates of water pickup are 300 to 500 percent per minute, many times higher than typical bench-scale tests would indicate. Within a few revolutions, newsinks may pick up six to twelve percent water. This implies that obtaining ink/water balance is not limited by the rate of ink/water mixing on-press.