Ink film constructions

A printing system for printing upon fibrous substrate, the fibrous substrate selected from the group consisting of an uncoated fibrous printing substrate and a commodity coated fibrous printing substrate, the printing system comprising:

• a. an intermediate transfer member (ITM) having a silicone release layer;
• b. a quantity of a water-based ink formulation comprising (i) a solvent containing water and, optionally, a co-solvent, said water constituting at least 8 wt. % of the formulation;
• (ii) at least one colorant dispersed or at least partly dissolved within said solvent, said colorant constituting at least 1 wt. % of the formulation;
• and (iii) an organic polymeric resin having an average molecular weight of at least 8,000 which is dispersed or at least partially dissolved within said solvent, the resin constituting 6 to 40 wt. % of the formulation, the ink formulation providing at least one of a first ink-formulation feature and a second ink-formulation feature,
• c. ink-jet printing heads configured to deposit liquid droplets of the water-based ink formulation onto the ITM release layer;
• and
• d. an impression station configured to transfer, from the ITM release layer and to the fibrous substrate, a residue film that is formed by drying of the liquid droplets, wherein the printing system is configured such that the transfer of the residue film to the fibrous substrate produces an ink dot construction comprising a plurality of ink dots that are disposed on the fibrous printing substrate so as to provide all of a first, second, third, fourth, fifth and sixth ink-dot-construction features:
• i. according to the first ink-dot-construction feature, each ink dot of the plurality is fixedly adhered to a top substrate surface of the fibrous printing substrate;
• ii. according to the second ink-dot-construction feature, each ink dot of the plurality contains at least one colorant dispersed in an organic polymeric resin;
• iii. according to the third ink-dot-construction feature, each ink dot of the plurality covers a continuous area of said top substrate surface;
• iv. according to the fourth ink-dot-construction feature, each ink of the plurality is disposed entirely above said continuous area, such that a projected perpendicular line, extending down towards said top substrate surface, first meets said ink dot, before meeting said top substrate surface, at every point in said continuous area;
• v. according to the fifth ink-dot-construction feature, each ink dot of the plurality has a diameter of 15 to 300 micrometers;
• vi. according to the sixth ink-dot-construction feature, each ink dot of the plurality is characterized by a dimensionless aspect ratio (Raspect) defined by:
• Rasect=Ddot/Hdot
• wherein Ddot is said diameter;
• and Hdot is said average thickness;
• and said aspect ratio is at least 50;
• and
• vii. according to the seventh ink-dot-construction feature, each ink dot of the plurality has an average or characteristic thickness of at most 1,800 nm,
• wherein according to the first ink-formulation feature the ink formulation is characterized in that the weight ratio of the resin to the colorant is at least 1.5:1, and according to the second ink-formulation feature the ink formulation has at least one of:
• A. a viscosity of at least 2 and at most 25 cP for at least one temperature in the range of 20-60° C.;
• and
• B. a surface tension of not more than 50 milliNewton/m for at least one temperature in the range of 20-60° C.