FAQs
Why do I sometimes see a galvanized or mottled appearance when printing solid colors on what is supposed to be a graphics grade linerboard? What can I do about it?
There can be a number of reasons for a galvanized appearance, often termed “print mottle,” of printed solids on linerboard. Print mottle can be caused by the substrate, an excess quantity of ink, or by the type of ink you are using. Substrates that are heavily calendered (passed between two steel rolls under heavy pressure) can crush portions of the sheet called fiber flocs. These crushed areas of the sheet, usually 5/8 of an inch in diameter or smaller, will have more ink hold out that the uncrushed areas surrounding them. The non-uniform ink holdout takes on a galvanized appearance when a solid patch of ink covers the crushed and uncrushed areas. Increasing the volume of ink only exacerbates the problem. Excess ink, alone, can sometimes cause print mottle. Transparent inks tend to reveal mottle more than opaque inks. Review the design of the printed area to see if opaque inks can be used instead of transparent inks. If you are building process colors, then the problem is a little more difficult to solve. Consult your paper supplier about using a lower hold out grade of paper that will meet your printing needs while minimizing the amount of print mottle.
