Page 14 - January 2017
P. 14

|  Try Ready Salted for Crisper Print | |  Ron Watson (6955)  |


             s a result of attending The Print   books and mailings, and newspapers
             Show in October last year, I    on newsprint. These papers are porous,
       Areceived a booklet about Inkjet      absorbing water from the ink and
       Printing and how it has developed.    carrying pigment or dyes into the body
       The BPS has been given permission     of the paper, reducing end density
       to reprint the article below in Small   and colour gamut. Worst case can be
       Printer thanks to the editor of the   show-through through capillary action.
       Digital Printer magazine, Barney Cox.  On coated paper there is nowhere for
                                             the water to go, resulting in spread and
                                             smearing, with problems drying the
                                             ink.
                                             A pinch of salt

                                              A signifi cant development at Drupa
                                             was much-improved quality from
                                             water-based inkjet onto standard offset
                                             papers. This is through improved ink
                                             technologies including higher pigment
                                             loadings and primers that can be fl ood-
                                             coated before printing, or inkjetted into
                 HP HDNA micrograph          position. The most common primers
                                             are salt solutions with surfactant
         One reason for highlighting this    wetting agent. Salt crystals cause rapid
       technology is because all the major   agglomeration of the pigment at the
       litho manufacturers are joining forces
       with various digital companies to
       produce machines which combine
       the two technologies. Even Heidelberg
       have a hybrid machine under beta
       testing. This is a company who used to
       sell a digital machine alongside their
       litho machines, then sold it on and
       have now come back into the market,
       although in a different format.
         It would seem that inkjet will be
       the system of choice over the toner
       method for the major producers,
       but in this fast moving world of print      Kodak Ultrastream micrograph
       technology, who can tell what will    surface of the paper. The salt absorbs a
       happen in another few years?          portion of the water, rapidly increasing
         Interaction between the substrate   the ink viscosity so that it does not
       surface and ink is the critical factor   spread unduly avoiding uncontrolled
       that determines inkjet image quality.   dotgain. Paper makers are developing
       Much inkjet is on uncoated paper for   specially treated coated and uncoated

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