New Cures for the Common Coat
On-press sheetfed systems raise to the next level the appeal of shiny sheets, gloss/dull contrast, product protection, and quick handling.
By Debora Toth, Project Editor -- graphic arts online, 3/1/2001
The on-press application of liquid coating to paper has become so predominant-as a production efficiency and a competitive requirement-that very few sheetfed presses with six or more printing units are being installed today without at least a single tower coater and extended delivery.
On-press coating for packaging or specialty printing has been around for some time, but with the development of aqueous (water-based) formulations, the process has become much more common on presses in commercial printing operations, rather than among specialists. More than five years ago, commercial printers began using multiple coating units, for example, to capture a gloss and dull contrast.
More recently, unique configurations that use ultraviolet (UV) light energy to cure a special coating applied over semiconventional or hybrid inks have become popular.
An even newer development involves complex, extensive sheetfed press configurations with multiple coating and drying units; one project planned for completion this year consists of six nonperfecting printing units and an equal number of coater or dryer components, plus an extended delivery. In this configuration, a coater/ dryer combination is located after the feeder, ahead of the printing units; after printing, two additional separate coater/dryer units process the sheet before it passes to an extended delivery.
A principal goal is to precoat lower-grade paper, to achieve a better printed result.
Advantage on three fronts
The popularity of on-press, in-line coating makes perfect sense. Once it's dried (or cured), the liquid coating enhances and protects the printed sheet; it allows immediate handling, whether to turn the pile over for second-side printing or to transport the sheets to the bindery, without having to wait for the inks to dry or applying spray powder to prevent ink setoff; and it permits vast creativity in controlling the appearance of the sheet, say, overall dull with spot gloss, matte with satin finish, a pearlescent look, dispersion and so on.
A growing number of innovative printers are exploiting this press capability to attract designers and high-end clients that want a more interesting, unique printed piece. Many printers are aggressively marketing coating and working with both suppliers of coatings and drying systems and with print buyers to overcome technical limitations and gain unique processes that give them a competitive edge.
"In general, we think that up to 85% of six-color 40"-wide sheetfed presses are sold today with a coater," says Ray Prince, senior technical consultant for the Graphic Arts Technical Foundation (GATF), Sewickley, Pa. "We're also seeing more coaters being added to 28" sheetfeds."
Bringing it in house
"Because the UV and conventional processes weren't compatible, the old method was to print a job and then send it off line-to a separate machine or to an outside specialist-to be coated," says Jeff Miller, chief operating officer of Grafix North America, Burr Ridge, Ill., developer of the CoCure process. "With today's hybrid systems, printers can print and coat in line on their own presses. The cost savings, the quicker turnaround, the gloss achieved, and rub resistance are major factors why printers are coating in line."
In fact, Miller notes, some purchasers of CoCure systems have no UV business to start with, but are buying the equipment entirely on speculation.
Adds Mike McGovern, "The properties that UV coatings offer were an instant success with cosmetic packaging and other applications where gloss and protection of the printed surface were desired. A glossy package still connotes high quality to a consumer."
McGovern, sales and marketing director for energy-curable-sheetfed and water-based products, for Sun Chemical, Fort Lee, N.J., says printers are installing coaters because the end users find that the gloss and package protection adds to their sales.
He says, "Newer technologies like Sun Chemical's Hy-Bryte inks and coatings allow a sheetfed printer to print and UV coat in line with no 'glossback' [later dulling of sheen] and without the need to change out blankets or rollers affected by UV. The coated sheets have a high gloss, cured and ready for further processing."
Sun Chemical has developed a Hy-Bryte cost-comparison worksheet, endorsed by Grafix North America, to help printers compare the costs of UV coating in a second press pass, sending UV coating to an outside supplier, and UV coating in line in house.
Pricing comparisons
"Water-based coatings add about a dollar to the printer's consumables cost for 1,000 square feet of coated product," says Jim Fried, product manager in charge of coatings for Wikoff Color Corporation, Fort Mill, S.C. "UV coatings add about $2.50 to the same 1,000 square feet," which is on top of the upcharge for hybrid inks.
On the other hand, printers that coat on press can save money in much-improved efficiencies, from turning over jobs faster to encountering fewer problems.
Printers that have presses that are not equipped for in-line coating face additional costs. "The cost of dedicated UV equipment is significant," says Miller of Grafix North America. "To retrofit a six-color sheetfed press for full UV costs from $230,000 to $500,000."
Environmental aspects
In discussions about aqueous coatings or processes using energy-curable techniques, questions inevitably arise about the environmental aspects.
Says Fried of Wikoff, "Some water-based coatings contain a small percentage of alcohol but the levels of volatile organic compounds [VOCs] are very low. The chemistry of water-based coatings is no more harmful than a can of latex house paint.
"As for UV coatings, they require special equipment, such as UV lights, to 'cure' the products. But the unique chemistry of UV coatings requires the use of lower molecular weight materials that some people are sensitive to. This requires special precautions in handling. We insist that our customers be fully aware of potential problems that occur with UV and make sure they understand the simple steps normally needed to avoid those problems."
Grafix North America calls hybrid UV a "no-VOC process" that's more environmentally friendly than aqueous.
Lots of choices available
More than 20 manufacturers offer coating products, some with 200 different types, in dozens of formulations created for various combinations of presses, application equipment, substrates, and inks.
Up to now, aqueous coating has been the method of choice for commercial printing since it provides fast-drying capabilities as well as rub resistance.
"We've been growing in the double digits," reports Mike Lauesen, president of Nicoat, Bensenville, Ill., a coating manufacturer that caters primarily to high-end commercial printers. "Quick turnaround has the been key use of aqueous coating. But we've been introducing new coating products that have better protective properties and make offset stock feel like satin."
Hybrid comes into its own
In the last two years, so-called hybrid UV technology-which combines energy-curable coatings with semiconventional inks-has become one of the hottest trends in press discussions. Appropriately, the technology began with an idea from a printer.
Curtis Fong, vice president of Fong & Fong Printers and Lithographers, a large, high-quality sheetfed printer in Sacramento, Calif., had clients with UV coating jobs. "Hybrid UV technology evolved out of necessity," says Fong. "Prior to this technology, the only way to get a high-gloss coat from UV was to produce it off line or use a dedicated double-coater press, choices that were very expensive. For our clients, it wasn't worth it. So I started to wonder why UV coating couldn't be done on a single-coater press."
Fong began discussions with Grafix North America, at the time a supplier of drying lamps; this led to six months of intensive testing at the Fong & Fong facility. After development of a hybrid UV ink by Ink Systems of Los Angeles, tests began on Fong & Fong's six-color 40" Heidelberg Speedmaster CD 102 press. Later, Grafix North America patented the process and named it CoCure.
Process becomes popular
Grafix North America has sold 35 to 40 CoCure systems in the United States since its introduction in 1999, the year that the process won the GATF InterTech Technology Award. By year's end, the company expects to have more than 70 installations in operation.
The process, which uses hybrid inks that permit use of conventional components and processes, lets printers achieve high gloss with UV coating and to minimize the loss of gloss over a 24-hour period. Equally important, says Miller of Grafix North America, the CoCure process allows the press to be changed over rapidly to print conventional inks and apply an aqueous coating.
"Right now we recommend using either one or two single-lamp UV interdecks positioned between the last printing unit and the coater to partially set or cure the ink," says Miller. "At the coater, UV coating is applied, then a three-lamp UV curing system placed at the end of the press performs the final cure."
With this configuration, he says, printers generally can expect to achieve gloss readings in the low 90s and to hold that gloss level to within three to five points even in areas with heavy ink coverage.
Miller adds, "Interesting as the high-gloss results produced on paper are, many printers are sensing the advantages that CoCure offers on nonabsorbent substrates such as plastics and foil, which traditionally proved difficult to print utilizing conventional inks."
Second hybrid solution.
The Technotrans America Sheetfed Division, Corona, Calif., is marketing its own hybrid UV coating technology. This system configuration consists of two individual single-lamp interdeck curing units, one located between the last printing unit and the tower coater, the other between the last and second-to-last printing unit.
The interdeck lamps are designed to operate in conjunction with a three-lamp final UV curing system located in the press delivery. The lamp power output is 160 watts per centimeter each, with 200 watts per centimeter available for special applications.
Technotrans is completing its first installation this month at Edward Enterprises, a commercial printer in Honolulu that operates a six-color CD 102 press with coater and extended delivery.
.and another option
Yet another option is a curing system, developed by Aradiant, Palmyra, Pa., that incorporates a new drying technology that is not UV and does not require water-based coatings to eliminate spray powder. Jeffrey A. Umberger of Aradiant says that the system can produce enhanced gloss results when running in-line double coatings or UV coatings over conventional inks as well as better drying with coatings.
The Aradiant system works by tuning frequencies of radiant energy to efficiently dry each ink film. Cold-dry air is incorporated throughout the press. The system utilizes interstation drying modules for each ink film independently, allowing for multiple exposures of radiant energy.
Applying the coating
In addition to the vast number of coatings being introduced, equipment manufacturers are introducing products to help printers lay down an even coat on press.
Last fall, Epic Products International, Arlington, Tex., introduced its CoatTech Anilox System, which utilizes a lightweight, carbon-fiber anilox roll and quick-release enclosed doctor chamber to reduce such coating problems as streaks, marks, and the "orange-peel" effect.
Says Epic Products president Tyler Dahlgren, "Our engineering teams implement all installations, so the CoatTech System can be added to virtually any existing press. Immediate quality improvements are seen without the need to purchase a new press."
Chambered doctor blade
Another chambered doctor blade system manufacturer, Harris & Bruno Machine Company, Roseville, Calif., supplied its first systems to the offset industry in 1995.
Known as the LithoCoat Conversion system, it is an upgrade to existing tower coaters or in-line coaters. Existing multiple rollers are replaced with a ceramic, laser-engraved anilox roll and a chambered doctor blade system. This conversion reportedly allows the application of uniform coating weights to spot or full coverage applications of aqueous coatings, UV, and varnishes.
To date, Harris & Bruno has placed more than 100 offset installations worldwide. These include Quebecor World George Rice & Sons, Los Angeles, a high-quality commercial printer, which installed the LithoCoat system in January 2000 on four of its sheetfed presses; Anderson Lithograph Co., Los Angeles; and Quality Graphics, a high-quality sheetfed printer in Roselle, N.J.
No problems with streaking
"About 60% of everything we print is coated," reports Bob Zimmon, vice president of manufacturing for Quebecor World George Rice & Sons. "We're able to provide better consistency with coatings and we have no more problems with streaking and striation with water-based matte and dull coatings. We've also resolved issues of uneven coatings, 'orange-peel' effect, and lack of control with sheetfed spot UV coatings."
He adds, "We're even able to produce matte and dull coatings for customers, whereas before we would only varnish and apply some satin finishes. Today we're also able to offer water-based spot coating, instead of being restricted to doing an overall flood coat or nothing at all."
Zimmon concludes, "Our clients want the latest technology available in the printing process, including metallic inks, overall and spot aqueous, UV interdeck drying, and UV coating running on eight-color presses. On any given day, it's not uncommon for us to be running five different eight-color sheetfed presses, each running a different jobs and each requiring a different coating."
Coating on a web press
Even web printers are beginning to develop on-press coating and curing capabilities. Woodruff Printing Inc., a 44-year-old, family-owned sheetfed and web printer located in Salt Lake City, Utah, began to use on-press UV curing to differentiate its business from that of other sheetfed printers.
"We converted our Sanden forms web press to ultraviolet curing with a sheeter at the delivery end," says Mark K. Woodruff, president. "Now we can compete with heatset web printers."
Woodruff uses the Sanden press to print brochures, newsletters, and newspaper insert jobs.
Slow evolution on a web
For the most part, the use of coating and curing on web presses is evolving slowly.
"The only UV coating I'm aware of is for some magazine covers, by way of an overall flood coat or spot coating," says Ray Prince of GATF. "A web printer will only use UV for protection of the sheet or to get a high-gloss look, such as for automobile brochures. To coat both sides on a web is a very expensive machine cost. My guess is that 1% of web printers have on-press coating systems."
From water to energy
At its founding in 1980, Cork Industries, Inc., Folcroft, Pa., offered water-based coatings and adhesives; in 1995, it began formulating energy-curable UV and electron beam (EB) coatings.
Today the company offers its Cork Kote aqueous coating line as well as a Cork Kure UV and EB line.
Other active suppliers include Craig Coatings, Newark, N.J.
Flint Ink, Ann Arbor, Mich., offers gloss and high-gloss waterbase coatings for general-purpose applications on coated paper and paperboard. FDA and stampable and UV coatable formulations are available; matte coatings can be obtained with satin or matte finish.
Flint Ink's polyboard coatings offer high rub- and grease-resistance, while specialty coatings are available with high product-, rub-, and heat-resistance for use on both coated papers and nonabsorbent specialty papers.
Nicoat markets a variety of coatings to the sheetfed and web market. Nine water-based coatings are available to sheetfed printers, including gloss, dull waterbase, satin, and work-and-turn. Gloss, satin, and pearlescent UV coatings are available. For the heatset web market, Nicoat offers N-Gloss heatset, heatset, and dull heatset coatings. "We are working on a UV water-based coating," says Nicoat president Mike Lauesen.
Notable pioneer
Sun Chemical, whose General Printing Ink (GPI) unit is notable as a pioneer in UV coatings, began offering the products in 1969. Sun Chemical now offers a full line of UV and EB coatings to all the major markets: commercial sheetfed printing, heatset web offset, and flexible packaging, as well as conventional and energy-curable folding carton and flexible packaging.
Says Mike McGovern, "Sun Chemical, which was involved with the CoCure process almost from its inception, offers the Hy-Bryte ink and coating system. With feedback from our customers and further laboratory research, we plan to introduce the Hy-Bryte II system this year. The new inks will set even faster, with less glossback and better lithographic performance."
Wikoff Color offers a full line of graphic arts coatings, both water-based and energy-curable.
Last year, Wikoff sold more than 200 different types of coating products, some of which were minor "tweaks" that customers requested or required. Says coatings product manager Jim Fried, "We are not afraid to make a product specifically to fit a single customer need, even for a special job."
