Streamlined Artistry
The highly evolved and standardized process of offset platemaking still leaves some room for improvement.
by Jessica Millward, Associate Editor
THE SOPHISTICATION OF existing offset platemaking processes has not encouraged complacency among equipment suppliers. On the contrary, rising competition from flexo, as well as increasing adoption of CTP and DI practices, have fostered a more innovative path to better plates and processing.
Science bests art
In offset platemaking's struggle with art versus science, it seems the latter won several years ago. And that is a good thing, contends Richard Butler, product development manager for Fuji Photo Film U.S.A. (Graphic Systems Division).
"Really, what was the purpose of the 'art' part of producing plates?" he wonders. "Wasn't it to compensate for results that were not consistent?" Butler insists having a firm shop standard produces a higher percentage of good plates, and also leads to easier correction of inconsistencies.
Presstek Product Line Marketing Manager, Off-press Products, Marc Johnson, agrees with the benefits of standardization, and counts them as a chief reason for the move to CTP. "One of the most important advantages of going to CTP is to reduce variability in multiple processes."
Creo, too, has recognized the significance of CTP's standardization capabilities. The company's SQUAREspot™ thermal imaging technology builds on inherent CTP reliability by improving image integrity. SQUAREspot employs a non-gaussian laser swath—meaning the laser energy exhibits virtually no variation across the width of the exposing laser spot. The result is an extremely steep energy profile that consistently maintains dot shape and size on plate, despite changes in the location of the exposure threshold. The technology is designed to deliver halftone dots that are virtually immune to normal process variations such as laser intensity, plate emulsion thickness, and processor chemistry strength.
This reliance on scientific consistency doesn't wholly exclude the element of art from platemaking, either. As Chris Estes, product marketer for Xanté Corp. attests, the tools for plate control are just slightly different. He notes, "Although the mechanical/analog methods are rapidly becoming digital, the ability to control the output is the same." Estes argues CTP devices, computers, and lasers are just a more controlled version of the light tables, red litho tape, and dark rooms of the analog process.
Growth opportunities
Of course, certain aspects of the offset platemaking process still invite improvement; even established methods are far from error-free. Estes cites prepress as the chief source of difficulties. The abundance of creative elements that need to be coordinated, he admits, renders the transition from design to execution a potentially "bumpy road."
Butler sees opportunities for better platemaking performance in the exposure step. For instance, he mentions the disparity in output values between older and more modern light sources. To regulate output figures, new offset platemaking systems feature digital readouts of light intensity values and bulb hours.
Vacuum drawdown times are another potential source of inefficiency. As Butler explains, too short a drawdown time means bad contact and poor reproduction. With an overly long drawdown, the printer faces considerable waste in production time. In redesigned platemaking equipment, vacuum times are being made programmable for consistency.
Creo's Chris Allen, product manager, VLF Products, believes integration of stochastic screening in the offset platemaking process may improve finished products. Creo's Staccato® stochastic (FM) screening software, bundled with the Trendsetter VLF Quantum, reduces variations in dot gain, wet trap, and color contamination from paper. The random nature of halftone patterns also means mis-registration doesn't cause color shifts. Such stability lends printers the ability to replace custom colors with process screen builds.
Presstek has focused its efforts on CTP development, in order to combat what the company identifies as "cost of error." Johnson states the term describes how, "the later on in production an error is caught, the more steps will have to be re-done to recover."
He uses a traditional imagesetter environment as example—a type error caught on press-check would necessitate backtracking several steps within the printing process. Whereas with CTP and digitally generated plates, Johnson argues, elimination of film and plate-burning allow the printer to keep the bad job on press and wait for good plates, in many cases within 10 minutes.
The post-image processing of plates stands to gain in efficiency as well. Johnson attests to the temperature variability possible in processors or ovens, as well as the variance in strength and oxidation levels that may exist in processing chemistry. New, solely water-wash plates eliminate guesswork, he says.
