Tom Kubinski Mary Albers www.sextonprinting.com |
November 2001
Ink Tour notes from TK's Korner The first electronic TK's Korner's focused on paper, one of the two main factors in a quality print job. This one will focus on ink. For those of you who did not make our very informative tour, I will try to shed some color on this topic. The tour was at Flint Ink. Flint was established in 1920 and currently has over 100 locations worldwide. They produce oil-based ink for web heatset, newsprint, offset for both commercial and packaging industries, water-based flexo, solvent-based flexo, gravure and news injector. See photos from the tour
Basic ingredients of ink: Flushed Pigment, which is pigment predispersed in varnish. Flushed pigment is the colorant portion of an ink formulation. Compounds, which could be wax, Teflon or any other of the many performance-enhancing materials used in an ink. Fillers could be different forms of clay, which promote viscosity as well as hold an ink together under the punishment of printing. For matte ink, one could use silica. Additives can promote drying, fight water on press, give ink a better release from the blanket and less pick on the paper, and fight skin-over in the can. In any case, it's important to choose the correct additives for the job. Your printer needs to be well informed on the stock and its end use. Oils are used to wet down the formulation and control tack. Linseed oil and tung oil promote a strong final dry. Deodorized petroleum distillates help accomplish a fast set because they flash off quickly in a web oven or under IR lights.
Shelf life of ink: Metallic ink has a shelf life of about one month or so, depending on the amount of metallic pigment in it. Because of pigment oxidation, the ink color starts to tarnish and the tack/viscosity of the ink changes.
Special Notes About Metallic Inks In addition, they can cause grief on press when used in wet traps. Even when the metallic and overlying color are specially formulated to work together in a wet trap, the result is never as good as in a dry trap. Metallic ink has metal flecks in it to give it its shiny appearance. You need to be aware that metallic inks do not show their true colors until the flecks float to the surface as the ink sets. When the ink sets, the flecks lie at different angles and reflect light. Note that when you overprint metallics with aqueous coating, you disrupt the light reflection and loose some metallic appearance. For the above reasons, metallics should be bought on a job-specific basis.
Job Continuity: One ink can differ in appearance depending on the paper used. .To demonstrate, Flint took 15 different types of paper (recycled news to cast coated) and used the exact same PMS color red. In all, the people thought that at least 10 different colors of red where used. If you are planning to use different types of paper (substrates), please let your printer know. We may either run the standard ink or make a custom ink based on each different type of paper being used. In either case, drawdowns will come in handy to let you know how each ink will be affected.
Drawdowns: You can even request drawdowns half coated with either a varnish or aqueous. Just remember that they do them as dry traps only (due to the nature of the equipment). The results will be slightly different from what would be produced on press.
Color Matching: For those of you who want to know more about UV burn, the next TK's Korner will cover what UV burn is and what precautions you should take so you don't get burned on your next project.
If you would like to join me on the next tour, or if there is something that you would like me to address, or you know of someone who might like to receive TK's Korner, please let me know via e-mail at TKubinski@shapco.com or phone. Take care and have a great day.
Successfully, |