Polyester, the Other CTP Plate

It's not metal and it doesn't require film; no wonder the popular synthetic material is attracting renewed interest.

By Mary Reinholz, Associate Editor -- graphic arts online, 3/1/2001

Polyester. The word itself still carries a faint stigma even in the high-tech world of printing. But this synthetic plate material, which has been on the market for more than 20 years, is undergoing a makeover in keeping with the introduction of digital workflows and the demise of pasteups.

Although polyester plates these days can be imaged in specific platesetters, they continue to be widely used in imagesetters and are billed as a low-cost, transitional step into computer-to-plate (CTP) production. Suppliers trumpet their improved capabilities for short press runs aimed at printing quick black-and-white and spot-color jobs like checks, business cards, brochures, letterhead, and small books.

In the near future, some vendors report, polyester CTP may well encounter competition from affordable metal platesetters being developed in the two-up and four-up format (see sidebar on page 60).

Already well positioned

"In our experience, a lot of the 35,000 or so printing establishments at the lower end of the commercial market in the United States are already using polyester plates because they're much less expensive than metal and provide good quality today," asserts Ken Newton, senior vice president of digital systems and chief marketing officer for A.B. Dick in Chicago, a major supplier of polyester plates and equipment.

Newton claims that his company, along with Purup-Eskofot of Denmark, pioneered the use of polyester plates with analog cameras in the 1980s.

He concedes that dimensional instability used to be a problem because the material stretched. But that drawback is largely under control, Newton insists, maintaining that the plates can now print good process color.

Market study is due

Recognizing the renewed interest in polyester plates, last year the Graphic Arts Marketing Information Service (GAMIS), Alexandria, Va., commissioned a study of future market potential. The report is to be released at the end of this month, reports its author, William C. Lamparter, president of PrintCom Consulting Group, Waxhaw, N.C., who dubs the use of polyester plates in imagesetters as a "poor man's CTP."

Lamparter believes that an "inbred negativism" about polyester plates "goes back many years in the industry, especially among printers that consider themselves to be the 'highest quality' outfits in their home towns."

He continues, "I think most of this is old wives' tales, the result of the old camera-direct and camera-platemaking methods that started out at the low end of the business," he contends. "Today, [polyester plates] are much improved and people are using them to produce four-color jobs."

Comparison of investments

Depending on format size, the price of a metal platesetter can start at around $100,000 while a new imagesetter might cost from $35,000 to $80,000, according to Lamparter. Polyester plates cost about $2 to $3 each, depending on size, while metal plates can run as high as $10 each and more.

Says Lamparter, "In general, a little guy doesn't want to spend big bucks on a capital investment, so people in this category think they can stick with their imagesetters to expose polyester plates for many-but not all-of their needs."

Clearly, polyester plates present limitations. "They're not meant for producing annual reports, but then most printers don't print annual reports," says Dave Mitchell, vice president of U.S. sales for Purup-Eskofot, which manufactures both imagesetters and platesetters that allow exposure of film and polyester and metal plates in one machine.

Adds Frank Scott, vice president and director of research for the Graphic Arts Technical Foundation (GATF), Sewickley, Pa., "Typically, metal plates have a rated life of up to 100,000 impressions whereas polyester plates top out at about 25,000 copies. But to be honest, at the low end of the market, the typical run is 2,000 to 5,000 copies."

Testing a thicker plate

Scott notes that major companies are getting into the polyester plate market, including Heidelberg, which has been aggressively promoting its internal-drum Primesetter series of imagesetters, shown at the international Drupa 2000 show in Germany last May exposing polyester material with a thickness of 12-mil (12 thousandths of an inch). The capability, a first for the company, represents a means of eliminating the need for underpacking on press cylinders.

Heidelberg targets the imagesetters at small and medium-size print shops, which can use them to produce imposed film as well as polyester plates. The company is supplying the polyester materials, which are manufactured to its specifications by Mitsubishi Imaging.

"Standard polyester plates are mostly 8-mil thick, so printers would need to place an additional rubber sheet on the press cylinder to bring the printing height up to that of aluminum plates," explains Wiebke Stoltenberg, senior manager of prepress output for Heidelberger Druckmaschinen AG in Kiel, Germany. "New polyester plates are 12-mil thick, the same as aluminum. Printers don't have to do anything special to use them and they register better."

Stoltenberg says that Heidelberg offers imagesetters for two-, four-, and eight-up press formats and supplies polyester plates in all the sizes. "We support and recommend four-color work on two-up and four-up presses, and we're in the process of qualification on eight-up formats; initial tests look very good," she reports.

Until recently, printers with presses from 20" to 40" wide could choose from only a few imagesetters that could handle the 12-mil material.

Two major suppliers

The industry's two major suppliers of polyester plates are Mitsubishi Imaging, which commands about 70% of the market, and Agfa, which withdrew its 12-mil plate material a few years ago but may reintroduce it at any time in response to rising demand, says Marc Op de Beeck, Agfa's international marketing manager for graphic arts supplies and equipment. Op de Beeck is based in Agfa's headquarters in Mortsel, Belgium.

Agfa released an updated version of its Setprint Plus polyester plates at the 1999 Seybold San Francisco event. The material, available in the U.S. in 5-mil and 8-mil thicknesses, can be exposed in Agfa's AccuSet imagesetters as well as in its higher-end SelectSet Avantra and Phoenix lines.

Selecting the right thickness of polyester, says Op de Beeck, depends on the number of press units, quality level expected, and the handling of the material. "People buying dedicated polyester plate machines are usually using the plates for smaller print work and spot color or black-and-white. These printers, which likely don't need the extra strength of thick polyester, make up the biggest market at present."

Up to 20,000 impressions

Op de Beeck says that Agfa's 8-mil plates are sufficient for work on two-up, four-up, and even eight-up presses, noting that they can handle up to 20,000 impressions and hold a screen resolution of 150 lines per inch (lpi).

Jeff Troll, director of marketing for Mitsubishi Imaging (MC), Inc., Rye, N.Y., notes that his company manufactured its first polyester plates, analog Silvermaster plates, 25 years ago. It introduced the Silver DigiPlate in the mid-1980s, since updating the line in several other versions with a new emulsion and sensitivity to different light sources.

Silver DigiPlate materials, says Troll, are suited for use in producing one-, two-, and four-color jobs in runs up to 25,000 copies and resolutions up to 175 lpi. The polyester plates have a backing material that retards light penetration, which improves daylight loading capabilities.

"Silver DigiPlates, which can be exposed in just about any imagesetter on the market today, gives a sharper, first-generation image, which is better than going to a film intermediate," Troll maintains. He says that new emulsion technology provides better latitude on the press and accommodates a wider variety of inks and fountain solutions.

Although polyester and metal plates can be used in the same press, Troll says that a lot of variables are involved, including the specific application, type of press, and whether underpacking is required to bring the plate surface up to printing height.

Intermediate CTP step

Dean Meyer, Heidelberg's U.S. product manager for imagesetters, claims that his company's machines offer "the best of both worlds." Meyer says, "Customers that don't want to make the complete jump to metal CTP plates have an intermediate step: using imagesetters designed from the ground up to expose both polyester plates and film. Press operators can switch between metal and polyester, and with our 12-mil polyester plates, they don't have to worry about additional adjustments."

Heidelberg designed its four-up Primesetter 74 to produce plates for the 28" Speedmaster 74 and other medium-format presses, and the eight-up Primesetter 102 to serve the 40" Speedmaster 102 and other similar-size presses. A smaller film recorder, the Quicksetter 350, allows imaging of both film and polyester plates, in nine resolutions from 1,000 dpi to 3,386 dpi and screen rulings up to 175 lpi.

Optimizing switching

As Meyer explains, "All four-up and eight-up presses can use 12-mil metal plates, so changing over to polyester is best when using a 12-mil plate material. Otherwise, an underpacking has to be placed on the cylinder. Changing back and forth between metal and polyester is difficult if underpacking is required."

Meyer says some customers started using polyester plates 10 years ago; now he believes that about 60% of small presses use polyester plates of some kind and that the synthetic material is taking over a bigger part of the market segment. Polyester plates provide a resolution of from 50- to 175-line screens, he notes, but probably can produce no more than 20,000 impressions.

"For short runs, polyester makes a lot of sense," he continues, then admits, "fancy jobs, like fashion magazines at the higher end, are still best produced using metal plates."

A printer reports

Wayne Renn, production manager for Accucopy of Greenville, Inc., Greenville, S.C., says his company, a large quick printer, has been using polyester plate material "almost exclusively" for offset printing for the last four years. Recently, his company bought a Heidelberg Quicksetter 350, to prepare plates for its Quickmaster 46 press, which features a built-in processor.

Says Renn, "In just over four minutes-two and a half minutes for imaging and about two minutes for processing-the plate is ready to mount on the press."

Despite such glowing testimonials to the powers of polyester, some manufacturers of presses are resolutely sticking with metal, among them Karat Digital Press, North America, Fairfield, N.J. "We're metal men," deadpans David K. Bartram, Karat's director of marketing. "Real men don't fool around with polyester."