If Scumming is detected during the press run, the operator’s immediate action must be a comprehensive review of the fountain solution’s chemical and physical properties. First, the operator must verify the solution’s acidity level by measuring the pH (using a specialized meter or test strips). The ideal reading must be kept within a tight, slightly acidic range (typically 4.8 to 5.2). This pH stability is crucial because any shift can reduce the hydrophilicity of the non-image areas, directly leading to Scumming.

Secondly, they must ensure the solution temperature is stable; the chiller must maintain the solution in the lower temperature range (usually 8 to 12 degrees Celsius). High temperatures cause volatile components like IPA to evaporate rapidly, immediately destabilizing the solution’s balance and causing Scumming. While addressing the core chemical imbalance, the operator may perform temporary mechanical adjustments by slightly increasing the dampening level (water flow) via the control console. However, this dampening adjustment is only a temporary fix; the fundamental chemical and temperature parameters must be corrected to achieve long-term Scumming prevention and maintain consistent print quality.