Mercury Intrusion Porosimetry ISO 15901 Dynamic Surface Absorption Inspection Protocols
ISO 15901-1 porosimetry paired with dynamic sorption testing qualifies coating pore structures to prevent back-trap mottle and ink setting failures on press.
Inter-Particle Capillaries
Fluid Movement
Microscopic spaces between individual fibers determine the rate at which liquids travel through a sheet of paper or board. These inter-particle capillaries act as conduits for sizing agents and aqueous coatings during the surface finishing process. Liquid penetration depends on the total void volume and the geometry of these paths within the porous structure.
Wide openings facilitate rapid absorption while constricted paths delay fluid migration, directly affecting the uniform distribution of binders on the surface.
Structural Regulation
Manufacturers adjust the density of the fibrous matrix to modify the behavior of inter-particle capillaries during sheet formation. High pressure during calendering collapses the pores to reduce the cross-sectional area, which limits the depth to which starch or pigments can penetrate the stock. Tight control over these channels prevents excessive binder migration, which preserves surface strength and prevents the loss of additives into the bulk of the substrate.
Precise management of this internal network keeps coating chemicals on the exterior where they perform the required function.
Production Outcome
Achieving consistent print quality relies upon the predictable flow of ink vehicles into the structure of the substrate. Variations in the size of inter-particle capillaries cause uneven drying rates across a printed area, which results in mottle or inconsistent color density. Operators monitor the porosity of incoming stock to determine the appropriate viscosity and solids content of the coating applied to the surface.
A balanced distribution of these microscopic channels ensures that the material accepts aqueous liquids without compromising the structural integrity of the sheet.