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Mar 1, 1998 12:00 AM
After a promising start in the early 1990s,conventional waterless printing has stalled.
Waterless printing--a technology whose 30-year path of development has been characterized by promises, periods of apparent success and disappointments--has been poised on the sidelines for the past two years awaiting a new round of improvements.
Is this answer to the printer's dream of getting the water out of lithography about to be revitalized or is it to be relegated to a specialty niche? The answer depends upon whom you ask and how you interpret the answers.
Waterless printing remains a technology poorly understood by many printers. It is a process that comes close to offering the printer's nirvana of ultra-high quality at lower costs. Nevertheless, there is no industry consensus regarding the current value of waterless printing, the probability of significant process improvements or the long-term potential for the technology.
Printers' expectations and the rate of waterless adaptation vary considerably by the processes used. Basically there are three approaches to platemaking: 1) analog or conventional platemaking using UV exposures; 2) direct-to-press platemaking such as is used on Heidelberg's Quickmaster-DI and the Omni Adast 700 digital printing presses; and 3) computer-to-plate (CTP).
Let's look first at analog waterless.
In the mid-1960s, waterless printing was conceived as a way to remove water from the lithographic process. It was introduced by 3M, now Imation, as driography in 1970. Then, as now, the process is based on the fact that a thin coating of silicone rubber has a smooth, slippery surface to which specially formulated inks will not adhere. In the early waterless plates, the ink was attracted to bare aluminum. Today, the inks are attracted to a polymer resin in the image area.
The importance of temperature control in the waterless process was realized in 1972 when 3M conducted tests on a web press, achieving runs of more than 10,000 impressions from driographic plates without toning. The critical difference between the sheet-fed attempts to print waterless and the web tests was the temperature-controlled inking system on the web.
After struggling with the process and questioning whether sheet-fed printers would pay for the added cost of temperature-controlled inking systems, 3M abandoned its waterless efforts in 1977.
However, in the same year, Toray introduced a positive waterless process. With dogged persistence, Toray struggled with the process for some 20 years, including the development of a negative-working plate to satisfy the needs of the U.S. market.
By the early 1990s, conventional waterless printing started to achieve success in the U.S. market, peaking in 1995 when a shortage of negative-working plates developed, effectively cutting off new installations. Although a few major web printers continue to experiment with the waterless process, most American printers have turned their attention to other developments such as digital presses and conventional press automation.
The perception of a shortage of Toray negative-working waterless plates still persists. However, Fred Fusci, Toray product manager, emphatically states that there is no problem with supplying existing or new installations with the firm's plates. He concedes that providing an adequate supply of plates requires planning and usage forecasting by printers or dealers because the plates are manufactured only in Japan and inventoried by Pitman. Toray has increased its production capacity and can adequately supply the conventional waterless marketplace, Fusci asserts.
Nevertheless, conventional waterless printing has not regained its growth momentum. Today there are between 100 and 120 U.S. printers using conventional waterless technology, down about 20 percent since growth tapered off in 1995, according to Arthur LeFebvre, executive director of the Waterless Printing Assn. He adds that there are between 1,000 and 1,500 waterless installations worldwide, with Japan and Europe (particularly Scandinavia) the global strongholds of this technology.
LeFebvre notes, and PrintCom independent research confirms, that printers who have stuck with the process are highly enthusiastic about its benefits, i.e., high quality color, reduced dot gain and the ability to print higher ink densities with less dot gain, faster makereadys, reduced waste and color consistency. A small band of waterless advocates, many of whom have been successful with the process in the marketplace, have difficulty understanding the reluctance of the skeptics. Proponents of the process believe that its benefits outweigh its difficulties.
The believer/non-believer controversy regarding waterless printing reveals, however, a benefits paradox. Early in the development of driography, conventional waterless was seen primarily as a way to stabilize the lithographic process with a primary goal of reducing labor and material costs. As the process developed, it became apparent that waterless enabled the practical production of work with higher screen rulings (300 lpi to 500 lpi). By the 1990s, this heightened quality became the primary drum beat for waterless. Whether or not waterless is more or less expensive is the subject of debate.
Printers that run waterless all of the time seem to be achieving savings while those that use waterless only occasionally have difficulty making the process perform properly, negating cost savings. This issue is related to the printer's ability to obtain premium pricing in the marketplace for premium quality work.
Most waterless printers believe that their ability to produce ultra-high quality work enhances their position in the marketplace, resulting in increased overall print volume--not quality upcharges. Skeptics claim that the market for this high level of quality is thin, difficult to sell and yields lower profits.
A further paradox is that the development of waterless printing has resulted in the use of temperature controls on conventional sheet-fed lithograph ic presses, thus yielding higher quality levels. Research in the 1970s, for example, showed that dot gain was significantly reduced by controlling ink fountain temperatures. Waterless, therefore, has created its own tough competitor--temperature-controlled lithographic printing.
John Dowey, Heidelberg SpeedMaster market manager, notes that at least half of Heidelberg's presses are equipped with temperature controls. Most are single-zone systems intended to run conventionally. However, these systems can be upgraded to multi-zone configurations if a printer decides to run with waterless plates.
All of MAN Roland's 40-inch and larger sheet-fed presses are factory plumbed for temperature control. About 85 percent of the manufacturer's sheet-fed shipments are temperature-controlled presses. Rudy Valenta, MAN Roland sheet-fed press product manager, notes that temperature control improves quality whether printing conventionally or waterless.
The MAN exec also notes that work run waterless will appear to be of higher quality given the same set of color separations (the same screen rulings). This is because of the process' ability to print with higher ink densities and lower dot gain.
However, notes Valenta, the water in conventional printing provides other advantages such as ink emulsification, which delivers a kind of lubrication for ink transfer and aids in the release of ink from the plate to the blanket and the blanket to the paper. Ink emulsification also enables evaporative cooling and helps to clean dirt and hickeys.
Whichever side of the conventional vs. waterless issue you may be on, it is apparent that temperature control, particularly as presses run faster, generating more heat, is becoming a standard sheet-fed accessory. As a result, the gap is narrowing between the two printing concepts. While pros and cons of analog waterless continue to be debated, our industry has entered the digital arena.
In 1995 Heidelberg introduced its Quickmaster-DI press, which incorporates Presstek's Pearl imaging system. This imager uses thermal laser diode arrays mounted directly on the press and dry waterless plates. This small-format, fixed-image digital press is highly automated, integrated with the prepress function and prints a maximum size sheet of 18 x 13 inches at speeds to 10,000 iph.
Because the QuickMaster DI does not include zoned temperature control, care must be taken that waterless inks with a wide latitude for operating temperatures are used.
Presstek has now extended its reach to a larger 19 x 26-inch unitized digital perfecting press from Omni-Adast. The press is equipped with a single-zone temperature control for printing units and a separate zone for cooling of the imaging heads as standard. Multiple zone temperature control for individual printing units is available as an option.
Most printers purchasing these presses recognize that they are buying an integrated system that happens to be waterless. But it is the integrated press concept that is driving the purchase, not the fact that the process is waterless.
PrintCom estimates that currently there are approximately 700 digital imaging presses installed and operating worldwide. Of these, about 200 are in the U.S., giving these digital presses an edge over the number of conventional waterless presses in operation. Most digital imaging presses operate at least one full shift daily, while the majority of analog waterless presses operate in the waterless mode less than half the time.
Building on its success in the direct-to-press market, Presstek now has taken its PearlDry plate into the waterless CTP market. The plate can be imaged on Presstek's own CTP system, the Pearlsetter, as well as on Creo and Gerber equipment.
Although Presstek is the lone entry currently available in the waterless CTP market, the company can expect competition from several other manufacturers before the year is out. We expect a waterless CTP plate from Kodak Polychrome.
At Print 97, Polychrome announced its Quantum NAW CTP plate, a negative-working non-ablative thermal waterless plate with sensitivities in the 830 nm and 1064 nm wavelengths.
Overall, the best prospects for waterless would appear to be in the direct-to-press segment with these types of presses expected to show modest but continually accelerating growth.
The real market for waterless printing, at least for now, is as a replacement process for conventional lithography, making plates the old-fashioned way--from film. It appears that there is no imminent technical breakthrough or market entries that would create a mass movement to waterless printing.
The process, however, has distinct advantages and will continue to find applications where it bests conventional lithography for the highest quality, most cost-effective printing production approach. But the real growth of waterless appears to be highly dependent upon its ability to thrive in the direct-to world both on and off press.
Waterless printing may remain a niche process--but in niches there's often gold. Waterless is one of those technologies that every printer needs to understand.
Although many printers think of waterless printing as lithography without the water, in reality it is a different process.
Lithography utilizes a planographic plate that functions on the basis that oil (ink) and water (covering the non-imaged areas of the plate) do not mix. Lithographic plates usually are grained in order to better carry ink-repelling water in the non-image areas. The inked image area surface is a very thin layer, making the plate an almost smooth, flat surface.
Waterless printing utilizes a plate with an ink-repelling silicone coating. This coating is removed in the image area to create a cell with silicone walls and an ink attracting photopolymer on the bottom of the cell. The image area that carries the ink is recessed and is similar to a gravure or engraved cell.
Because the non-image area of the plate is a silicone layer and the ink is carried in a cell, the process is sometimes characterized as silicone intaglio printing.
The difference in plate materials, structure and basic technical modus operandi result in lithographic and waterless printing being processes with somewhat different characteristics. Each process requires different ink formulations and press running conditions. Achieving ink water balance is the science of lithography. Maintaining correct temperature is a critical operating requirement for waterless.
Silicone intaglio, with its recessed cell structure, carries more ink on the plate and can, therefore, print at higher ink densities.
Whenever solid ink densities are increased--waterless or lithographic--there is a corresponding increase in dot gain. However, because of the inherent difference in the plate structures, an equal increase in ink will result in less dot gain on a waterless press than on a conventional one. (At the same ink densities, waterless prints with a lower dot gain than lithography.)
When a kiss impression is made to transfer ink to a blanket on any type of press, pressure is applied to the image area. On a lithographic plate, the ink sits on top of the plate without any support structure for the dot side walls. As the dot is squeezed, it expands laterally, resulting in mechanical dot gain.
The ink well structure of a waterless plate provides support for the dot side walls. When a dot on a waterless plate is squeezed, the sidewalls minimize lateral dot gain.
Because waterless inks tend to have a higher working tack, slightly less dot gain occurs on a waterless press when the image is transferred from the blanket to paper.
Dot gain also occurs as ink is absorbed into paper. During ink absorption there may also be some loss in the fidelity of the dot shape. Lithographic inks undergo some degree of emulsification during printing. This causes the ink to be readily absorbed into the paper, creating dot gain and distortion.
With the water eliminated from the silicone intaglio process, there is no emulsification of the ink. The result is that the ink tends to dry more by oxidation on the surface than by absorption. The dot gain difference between is most noticeable on absorbent uncoated papers.
The ability to print high-resolution screening--300 lpi and up--is one of the key attributes of waterless printing. Lower dot gain, combined with the use of silicone coatings instead of water to create non-image areas, accounts for what is arguably waterless' capability to print higher screen rulings than lithography.
To create a dot on a waterless plate, the silicone is removed to reveal the ink-attracting polymer cell surface. The non-image area is, in effect, manufactured into the plate, making it possible to create very fine dots.
On a lithographic plate, the areas between dots must be wetted in order to repel ink. As the size of a lithographic dot is reduced to something under 10 microns, it becomes very difficult to consistently and properly apply water as is required to achieve ultra-high-resolution lithographic printing.
Although difficulty in removing the silicone from micron-sized dot areas on waterless plates requires a cumbersome and somewhat sensitive plate processing step, the end result is a plate with high-resolution screening.
The elimination of water and the utilization of silicone to create non-image areas, combined with the carrying of ink in recessed intaglio-like cells on the plate, is what makes the process technically different from lithography.
Silicone intaglio, or waterless printing, can be categorized by three different approaches in the way the plate is made. Analog or conventional waterless printing plates are made using a typical plateroom UV exposure approach. Currently the only supplier of analog waterless plates is Toray Industries.
Digital waterless plates are divided into two groups, depending upon whether the plate is made on-press or off press in a computer-to-plate (CTP) device.
The on-press approach is usually categorized as direct-to-press, while the off-press method is becoming known as computer-to-waterless-plate (CTWP). Although there are several digital waterless plates under development or in the alpha/beta test stages, the only current supplier is Presstek, whose PearlDry plate is used both on and off press.
Status and acceptance of waterless, a.k.a. silicone intaglio, printing is highly dependent upon the platemaking approach--analog, direct-to-press or CTWP.
Waterless printing is here to stay and, although it may remain a niche process, it nevertheless should be considered by printers investing in a new press, looking at new markets or attempting to differentiate their services.
The best sources for information about waterless printing come from the Waterless Printing Assn., P.O. Box 59800, Chicago, IL 60659; (773) 743-5677 or (800) 850-0660; FAX (773) 743-5756; E-mail: email@example.com.
The fastest way to get information is to go to WPA's Web site (www.waterless.org), which has links to the major waterless printing suppliers.
The Complete Guide to Waterless Printing is a comprehensive technical manual about the process. It is not only useful for the experienced waterless user but for anyone contemplating the process. Written by John O'Rourke, the waterless industry's most knowledgeable and experienced practitioner and now a product manager with Presstek, the guide is available from WPA. The price is $69 for association members; $89 for non-members. If you are interested in the intricacies of waterless, it's a worthwhile read.