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Jun 1, 2002 12:00 AM

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Although both visible light and thermal energy are used for direct digital imaging of offset printing plates using computer-to-plate (CTP) devices, the industry still tends to view thermal as expensive technology designed only for high volumes. That is actually a misconception. Let's take a closer look at some of the most common myths.


Thermal is expensive.
Violet imaging has been portrayed as the most economical way to make digital plates, based on the apparent price of the CTP device. This overlooks the total cost of ownership, however. Just as buying a $1,000 car is unlikely to lead to the lowest overall cost for transportation, selecting an imaging technology based on the price of the hardware alone is misleading.

Thermal imaging, in fact, can reduce processing costs and waste to deliver the lowest overall cost of print. Consider that thermal laser diodes cost about 100 times less than the most inexpensive visible laser sources, for the performance delivered. And the thermal diodes don't require a safe-lit, light-tight room, reducing facility cost and improving safety and the working environment.

Thermal media have few press chemistry incompatibilities, reducing cost and disruption if a press chemistry change is required. In addition, thermal plates store more reliably than many visible plates, thus saving costs on repeat jobs.

Thermal-plate processors tend to require less maintenance than silver processors. And the thermal diodes in the laser have a longer lifetime than visible lasers, which means fewer costly plating interruptions. The value of uninterrupted production is very high. After all, press time can be worth hundreds of dollars per hour — disappointed customers can cost a printer even more.


There aren't many thermal plates — and they cost too much.
There are, in fact, more thermal-plate manufacturers in the market today than those producing violet plates. Currently, there are 28 thermal-plate manufacturers, compared to two violet-plate manufacturers. Because of the many manufacturers and technologies available, thermal plates are competitively priced. High manufacturing volumes and competition continue to drive plate prices down.


Thermal is only for the big printers with high volumes.
Violet imaging has been targeted squarely at the lower-volume printers. But that doesn't make thermal inappropriate for this market.

Smaller printers have difficult choices to make. They can select violet, which is described as being “almost as good” as thermal. Or they can select thermal itself. It's a tough choice, but consider this: Research indicates that more than 10 percent of the CTP-installed base has already been retired. That's a surprising number considering that most of the equipment has been installed for less than five years.

It is obvious that some printers purchased CTP systems that have become obsolete, performed badly or were so expensive to operate they had no resale value. The merits of upgradeable, long-lasting and easily resold thermal imaging systems are clear in this marketplace.

Smaller printers, without the resources to thoroughly test the claims of the multitude of competing graphic-arts vendors, can rely on the experience and purchasing patterns of larger organizations that have made CTP decisions. Recent data on the currently installed base indicate that about 50 percent more thermal CTP plates are sold than visible plates, and equipment sales appear to favor thermal by a ratio of 3:1 over violet.


Violet delivers the same quality as thermal.
Only thermal SQUARESPOT technology allows stochastic screening in a production environment. Stochastic has significant on-press advantages. One of the most interesting is that color produced stochastically is much less affected by the tint of the paper stock, allowing the use of less bleached and more recycled (or lower-cost) paper and board.

Thermal also allows virtually continuous-tone printing by using 10-micron dots to produce extremely high print quality. And thermal, even without stochastic screening, provides excellent process control, speeding makereadies and resulting in fewer press adjustments.

Overall, thermal CTP imaging provides consistent printing throughout the run, cleaner colors and sharper dots. Not just for the “big guys,” thermal is an affordable, high-quality option for mainstream printers wanting to increase productivity and differentiate their companies in the marketplace.

Stochastic screening improves quality for Coastal Printing

Established in 1956, Sarasota-based Coastal Printing is one of Florida's growing printers. Because of its location, the firm has learned to take advantage of unique opportunities presented by its customers. Today, the company prints everything from business cards to art prints, with a growing specialty in printing on different types of plastics. The $7 million printer boasts six-color and four-color 40-inch presses, along with smaller one- and two-color presses and a full bindery. “We make what we can sell,” observes IT manager Don Kopf.

“We got into electronic prepress back in 1986 and had been doing four-page imposed film for eight or nine years,” explains Kopf. “Although computer-to-plate (CTP) would have been an easy step for us, we couldn't find a digital contract proof to meet our needs that was affordable. Then Creo introduced the Trendsetter Spectrum, which we bought immediately. It was the best of both worlds — it could make plates and contract proofs.”

Coastal also runs Creo's PDF-based Prinergy workflow and has been pushing the envelope by switching to Staccato stochastic screening for 90 percent of its work. “It was no big deal for us,” says Kopf. “We just pushed a button.”

Actually, producing stochastic screening was easy for the Florida printer, but there were a few process-control operations that needed to be tweaked. “We learned to tighten up the range of our activity levels on the plate processor to get consistent results from week to week, but that wasn't a difficult thing to do,” Kopf explains. “And we had to develop different tone curves. But it's worth a few adjustments. We get crisper detail, especially on product shots. Details such as hair or fur on animals look great, and photographs of people look very sharp — they just jump out at you.”

CTP is another world compared to analog, says Kopf. “It turns your operation into a manufacturing process. If you stay within the proven guidelines, the system works all the time. And Prinergy makes the process much easier, more flexible and foolproof. The Mac operator can RIP through complex work in minutes. Plates are always in register, fit one another and don't have spots, holes or scratches. We would not be printing on plastic without CTP. It allows us to match colors on paper and two or three types of plastic in the same campaign. That wouldn't be practical using conventional methods. During the past year and a half, printing on plastic has become a strong niche for us. Today, about 20 percent of our business is plastic, which is easy because we just choose different output curves. It's really slick with CTP,” concludes Kopf.