Mathematical Modeling of Mechanical Tone Value Increase across Recycled Testliner
Dynamic impression squeeze on porous recycled testliner forces lateral ink spread, requiring prepress Yule-Nielsen n-factor recalibration to prevent gain.
Wet Ink Film Thickness
Volumetric Layer
Direct physical depth measurement quantifies un-cured liquid ink applied to substrate surfaces during printing. Wet film thickness gauges measure liquid layer thickness in micrometres immediately following roller transfer. Controlling wet ink film thickness maintains target optical density while preventing mechanical set-off and drying defects.
Press operators adjust fountain key openings or anilox cell volumes to regulate fluid delivery rates across press beds.
Transfer Dynamics
Wet ink thickness governs optical color strength, trapping performance, and drying rate parameters on printed sheets. Thin liquid films dry quickly via oxidation or absorption but may fail to achieve required solid optical density targets. Thick liquid films maximize color saturation but risk ink slurring, tracking through transport rollers, and set-off in output piles.
Comb-type thickness gauges and roller wheel gauges measure liquid ink depth on smooth test surfaces during press setup. Flexographic printing controls wet ink layer thickness by selecting anilox roll cell volume configurations expressed in billion cubic micrometres per square inch. Maintaining uniform wet ink film thickness across web widths stabilizes ink drying rates and color consistency throughout production runs.
Drying Limit
Excessive wet film thickness prevents solvent evaporation in lower ink layers, causing skinning, soft ink film failure, and blocking. Insufficient film thickness causes ink starvation, producing patchy solid fields and poor rub resistance on finished packaging. High substrate absorbency rapidly drains liquid vehicles, complicating wet film measurement on porous uncoated paperboard.
Tone Value Increase Target Derivation for Uncoated Papers
Deriving uncoated paper TVI targets demands separating optical light scattering from capillary ink absorption using M1 spectral data to set inverse RIP curves.