plucking

Plucking occurs when the force needed to split ink film during printing exceeds the surface strength of the paper itself. Rather than the ink releasing cleanly from the printing plate or roller, it rips away fibers from the paper's top layers, leaving small holes, tears, or a rough, fuzzy surface. This is distinct from picking, which involves removal of larger chunks of the paper coating, though the two terms are sometimes used loosely in the trade.

The problem emerges at the intersection of three factors: ink tack (its stickiness or adhesive strength), paper surface properties, and the mechanical stress of the printing press. High-tack inks, commonly used in offset lithography and flexography to achieve good color saturation and transfer, pose the greatest risk. Papers with weak surface fibers, poor sizing, or low binder content are most vulnerable. Modern offset presses running at 200 to 300 meters per minute generate substantial mechanical force, and the risk intensifies with higher speeds and heavier impression pressures.

Preventing plucking requires balancing competing demands. Printers reduce tack by lowering ink temperature, adjusting fountain solution chemistry, or reformulating the ink itself, but these changes can compromise color strength or drying. Using a harder-surfaced paper, achieved through increased clay coating or improved sizing, provides a more robust solution. On the press floor, monitoring and adjustment occur in real time: adjusting roller pressure, reducing speed, or in some cases applying an anti-pick spray or powder to the paper surface. The condition reveals itself immediately as surface defects, usually visible at the print's leading edge where the ink first engages the paper.

Plucking is economically significant because it creates waste on every sheet affected and can halt production while adjustments are made. It is particularly troublesome in multi-color work, where the problem may emerge only on the final color station after investment in earlier passes. Different paper grades and coating systems have different pluck resistance; this property is sometimes specified by the mill and is a legitimate consideration in paper selection alongside brightness, smoothness, and absorbency.