Lucas-Washburn Kinetics

Absorption Variables

Surface tension and pore radius dictate the velocity of wetting within a given stock. Fluid density and dynamic viscosity introduce drag forces that restrict the rate of penetration during high speed coating applications. The formula assumes a uniform cylindrical geometry for internal channels.

Real world structures show high tortuosity and irregular void distribution that cause the observed flow to deviate from calculated theoretical values. Differences between experimental wetting data and the model output highlight structural variations in the fiber network.

Process Impacts

Pressurized delivery systems rely on accurate time constants to ensure even distribution across a moving web. Printing presses adjust fountain solution application based on the calculated uptake speed to prevent sheet distortion or ink bleed. Failure to calibrate for these rates results in poor adhesion or mottling during the bonding stage.

Correct application of this physical principle stabilizes the moisture balance throughout the entire converting line.