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.
Specific Void Volume
Pore Architecture
Internal air space within a paper matrix dictates how fluid penetrates the sheet during liquid coating or offset printing. Specific void volume measures the ratio of pore volume to solid mass in a porous substrate. Papermakers control this metric through refining intensity and wet pressing pressure on the paper machine.
A high ratio accelerates ink solvent absorption but risks print through if the fluid migrates too deeply into the web. Converting lines balance this property against binder demand to prevent surface dusting during high speed run conditions. Porosity values depend directly on the density of the cellulosic network and filler loading levels.
Exceeding nominal limits leads to uneven pick resistance and poor gloss retention on coated art papers.
Void Distribution
Pore dimensions vary widely across machine direction and cross direction profiles within commercial grades. Calendering reduces total pore volume by collapsing larger capillaries under mechanical nip pressure. Excessive nip loading destroys ink holding capacity by sealing the outer surface prematurely.
Printers adjust fountain solution delivery rates when processing sheets with restricted void structures to avoid emulsification faults. Substrates featuring uniform pore distributions maintain dimensional stability during thermal drying phases in heatset web presses. Laboratory mercury intrusion porosimetry maps pore throat diameters to predict varnish holdout performance accurately.
Fluid Retention
Liquid uptake mechanics rely on capillary pressure drawing vehicles away from pigment particles during the setting phase. Specific void volume dictates the maximum volume of oil a given paper weight can accommodate without striking through to the reverse side. Packaging converters monitor this parameter closely when selecting boards for barrier coating applications requiring low absorption.
Insufficient void capacity causes binder migration toward the surface, leaving weak bonds inside the base sheet. Optimizing internal space prevents blistering during rapid thermal conversion processes used in flexible packaging production. Finished packaging integrity relies entirely on maintaining consistent void geometry throughout the papermaking run.