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When thinking about the evolution of printing and the changes that have taken place since its earliest use thousands of years ago, consider that the only component that has not been replaced or reinvented is ink. When all is said and done, what makes printing really printing is the ink. It is what we look at, and what we see on the final product.
Early printers made their own black ink—there was only black back then—through much experimentation and trial-and-error in an attempt to make the image dry and stay put on whatever substrate was being used. Hand application of the ink was the most common method, since the number of copies needed was limited.
By the 1600s, Gutenberg's letterpress process was common throughout Europe and beginning to find its way to America. Demand for ink was growing, and ink manufacturing companies had already been established in Europe. By the late 1700s, there was a demand for printing and, thus, a need for printers. It was at this time that the U.S. printing ink industry was born.
The ensuing years have brought significant changes to the art of printing itself—first letterpress, then intaglio, gravure, flexography, offset, digital, and inkjet. Today, more than 200 printing ink facilities in the United States produce millions upon millions of pounds of ink to make sure there is something to see on the paper.
The More Things Change...
Still, after a thousand years, ink—although it is different in composition—is still ink. After you win the bid, buy the paper, create the image, make the plates, mix the fountain solution, load the paper, do the makeready, print the paper, cut the paper, and fold the paper, what do you finally look at? The ink! Though it is only 2 percent of the total cost of producing the piece, ink is the means by which a job is evaluated, appreciated, rejected, or accepted.
And yet, while ink is probably the most important component in print production, it is also the most underrated. If a printer needs to depend on one element of the process, it should be the ink. By eliminating doubts about one variable from the complicated print production process, printers can focus on the multitude of other physical and chemical components of printing.
Quality Control
Printers today desire very specific qualities in their choice of ink. They want an ink that stays open on press for extended periods of time, but that will dry instantly on the substrate. They want an ink with super rub-resistance, but which also can be coated, laminated, foil-stamped, and will stand up to the hottest laser copiers. They want the highest gloss, the best work-and-turn properties, no water problems, and super chemical and fade resistance. Today's printing inks are capable of providing these qualities adequately, and in a single formulation.
Printers know that an exceptional image is not achieved by ink alone. During the process, ink is subjected to a number of factors that continually challenge its ability to provide its intended level of performance. However, print production combines a multitude of components in addition to the ink—the pressroom environment, substrate, the press itself—and each of these must be carefully controlled. When a glitch arises, it is important for printers to be aware of the full scope of potential causes.
If you suspect a problem with the ink you are using, here are a few areas to consider:
- Substrate—If the paper is not pure white, it will change the color of the ink, due to the fact that almost all of today's inks are transparent. Some types of the bright white papers contain high amounts of fluorescent brighteners, which can make the colors appear different when viewed under different light sources. High acidity of the stock can be another factor, and can slow the drying process dramatically—while an exceptionally high porosity can cause chalking or "ink dry-back."
- Humidity—Picking problems result when the paper's coating loses its resiliency because of the excessive moisture. High humidity in the pressroom can be absorbed by the paper, resulting in slow drying. Humidity also can contribute to the tinting or toning during the press run. On the other hand, low humidity can result in static electricity in the pile, causing set-off and blocking when you are using certain substrates.
- Temperature—High temperatures in the pressroom can cause a breakdown in the ink over time, softening it to the point where it is emulsified too much. Emulsification causes a variety of ink-water balance problems, such as excessive dot gain. Conversely, low temperatures in the pressroom can result in poor trapping of ink films in four-color process work, as well as mottling or uneven printing because the ink will not transfer well under such conditions. The temperature of the fountain solution can also affect the ink-water balance and should be maintained at below 55 degrees Fahrenheit.
- Fountain Solutions—The pH and conductivity of fountain solutions can alter the drying characteristics of the ink, and they can change over the course of the press run. Alkaline paper can cause a rapid rise in conductivity, resulting in a spike in the pH—causing the plate to lose its water-loving nature in the non-image area. On the other hand, a too-low pH can cause drying and plate blinding issues. A too-low level of conductivity will result in poor ink transfer, once it has been emulsified. This is why it is crucial for the pH level to be periodically monitored to assure that it has not drifted.
- Ink Film Thickness—Heavy ink films can cause color changes, offsetting, and slow drying. Printing too heavy an ink film in solid areas will sometimes result in the screens filling in too much, making the image appear full. Printing with too thin an ink film results in ink starvation problems, such as mechanical ghosting, picking, and mottling.
Blanket and Roller—Uneven pressure settings can cause ink misting and dot gain. Another factor to consider is that rollers that are glazed will not transfer ink or water very well. When using an alcohol substitute, the durometer or "hardness" of the rollers should be lower to accommodate the "thicker" film of water. Worn blankets are another thing to consider, as they can result in poor ink transfer—causing the pressman to "push" the ink when it is not necessary.
The proper impression should always be adjusted to the thickness of the stock and its coated or uncoated surface; uncoated stocks should have more squeeze.
Press Cleanliness—It is a well-known fact that any leftover ink residue can alter the color of the ink and create what is called a "dirty" image. When printing light colors or pastel tints, a double wash-up is always recommended—especially after printing a dark color or black.
Additionally, making sure the journals and sides of the press are cleaned of debris or dried ink particles helps ensure that no hickies land on the press rollers, blanket, or plate during a run.
None of the aforementioned conditions are normally related directly to the ink itself, but rather to the effects of other variables on the ink. The varnish systems in today's printing inks are designed to be very forgiving, however they do have their limits. By controlling the other variables more strictly, the printer can eliminate almost any problem.
If any one of these possibilities is overlooked, it can manifest itself in a gradual deterioration of the performance and appearance of the ink. The result could be slow drying, poor rub resistance, low gloss, dry back, tinting, dot gain, chalking, piling, set-off, blocking, or ghosting.
Creating the Perfect Match
With today's manufacturing processes and precise quality control procedures, ink should never vary or change from batch to batch or can to can. Using quality ink products from a reputable manufacturer gives the printer control over this crucial production component and ensures that if all else is running at optimum, so will the ink.
Ink has been the one constant with all the changes in the printing industry over the years. Only the formulations have evolved to meet the demands of the times, and to support the printer in the most consistent way possible.
Recognizing the importance of ink in the process will ensure printers continued success in the future.
Joe Bendowski is the president of Van Son Holland Ink Corp. of America, a leading global printing ink manufacturer known around the world for producing high-quality, high-performance inks for every offset press. Mr. Bendowski can be reached at joebendowski@vansonink.com.
author: By Joe Bendowski