Products
Choosing a Computer-to-Plate (CTP) System
How printers can identify the core issues and select the system that best meets their needs
Printers considering the upgrade from film-based plate imaging to CTP are presented with many reasonable-sounding claims that are often contradictory. Ongoing discussion in the trade press suggests that the choice of CTP system begins with a discussion of imaging method, primarily thermal vs. violet (visible) light. As the largest developer and manufacturer of thermal CTP technology, Kodak has a clear self-interest in this debate. Having begun as a manufacturer of visible-light CTP systems and now a manufacturer of both thermal and violet digital plates, Kodak has experienced among its own customers the original shift from visible-light CTP to the adoption of thermal imaging technology. Having this intimate experience with both sides of the argument, Kodak is in a unique position to shed light on the issues critical to printers wanting to make a fully informed CTP investment.
What may be surprising to many is that the imaging technology is the last point of discussion in the choice of a CTP system. The guiding factor is, in fact, the business impact the anticipated investment is intended to deliver to the printer. Because the implementation of CTP can have positive impacts throughout the printer’s entire business, it is important that a decision-maker consider objectives beyond the obvious one of eliminating film from the plate imaging process. A few examples might include reducing print manufacturing costs, improving output consistency, differentiating presswork offerings, increasing throughput, fostering closer customer relationships, attracting new classes of business, or any combination of these and others. The decision about which technology to adopt should not begin with an assessment of the imaging technology, but rather with a thorough analysis of what the investment is intended to accomplish.
So why go CTP?
This simple, pragmatic, question is often neglected in the maelstrom of competing vendor claims. The reasons for printers to consider an investment in CTP are the same today as they have been since plates have been used in the production of presswork:
a) Eliminate manufacturing redundancy and the associated costs in time and materials, i.e. remove film from the plate production process.
b) Eliminate variation in the plate imaging process. Variation in plate imaging results in longer makereadies and increased time and material waste, compromised presswork-to-proof alignment, an inability to reliably run the finer screens increasingly demanded by today’s print buyers, inconsistent pressroom performance, and reworks.
By definition, any type of CTP device will eliminate film. Printers interested solely in reducing redundancy in prepress would appear to have a wide range of CTP technologies to choose from and logically gravitate towards the offering with the lowest device cost. However, that decision only addresses the first criteria and misses the more important business value of reducing variation in the process. Plates that are repeatedly imaged accurately and consistently reduce costs, improve pressroom efficiency, and help meet customer expectations in the pressroom, thus increasing profitability. Process control and stability in plate imaging is the key value in moving to CTP; the one that unlocks all the potential benefits and the return on investment (ROI) for the printer. It is the reason why thermal imaging was quickly embraced and adopted by the print industry when it was originally introduced as an alternative to visible-light CTP imaging.
Why is thermal more effective at eliminating plate imaging variation?
Stability, accuracy, consistency, and repeatability
For the printer, the integrity of the image on plate directly impacts the integrity and profitability of the pressroom. Early CTP adopters realized that plate imaging accuracy, consistency, and repeatability were key requirements of an effective CTP investment. Thermal imaging earned strong support because it proved to be both stable and consistent, using high levels of power (measured in Watts) to image relatively low-sensitivity plates. The plate coatings respond to exposure by forming an image at a threshold temperature, in a process that is essentially binary: either the image is created or it is not. Over- and under-exposure are virtually nonexistent, and imaging is very consistent.
For the printer, the integrity of the image on plate directly impacts the integrity and profitability of the pressroom. Early CTP adopters realized that plate imaging accuracy, consistency, and repeatability were key requirements of an effective CTP investment. Thermal imaging earned strong support because it proved to be both stable and consistent, using high levels of power (measured in Watts) to image relatively low-sensitivity plates. The plate coatings respond to exposure by forming an image at a threshold temperature, in a process that is essentially binary: either the image is created or it is not. Over- and under-exposure are virtually nonexistent, and imaging is very consistent.
Comparatively, violet and other visibile-light-sensitive technologies must be used in a light-safe environment, exposing photosensitive chemical coatings with tiny amounts of imaging power (measured in milliwatts). In this situation, even slight variations in power can cause over- or under-exposure of the plate. The quality of the imaged plate can also be affected by minor variation in plate manufacture, storage temperature, humidity, handling, and the development process. If the promise of CTP is to deliver consistency, by their very nature, visible-light CTP systems (including violet) exhibit greater potential for plate imaging variation. Indeed, plates imaged using visible-light CTP can exhibit inconsistencies similar and even greater than those of a film-based workflow. The cost of that plate imaging inconsistency shows up in the printer’s most expensive asset—the pressroom—in the form of longer-than-necessary makereadies, difficulties aligning presswork to proof, and difficulties delivering consistent repeat jobs.
Versatility, flexibility, adaptability
While all available imaging technologies may do the job of exposing an image on plate, none can claim the flexibility and adaptability of thermal imaging. Thermal technology is used for imaging all three of the major press-based printing processes: offset, flexography, and gravure printing. With thermal plates, prepress operations can take place in daylight. Consistent thermal imaging also enables the reliable printing of finer halftone and FM screens, which are increasingly demanded by today’s critical print buyers. In addition to imaging plates, thermal imaging can also be used to expose proofing media on the same device when there is a need to proof the actual halftone dots. Thermal also drives the vast majority of digital offset presses (including those from Heidelberg, Presstek, Komori, MAN Roland and KBA). It is also the enabling technology for true processless plate making, which removes yet another imaging variable from the process.
If that’s the case, why the new interest in violet-light CTP?
Visible-light systems, including violet-light CTP, have always existed as a competitor to thermal technology. Early CTP devices, which became commercially available around 1994 (including those from Kodak), were based on visible-light. Visible-light imaging was, after all, the technology used in the film imagesetters of the day. Violet-laser devices now represent the best of the visible-light systems available. Compared with its earlier non-thermal counterparts, violet technology offers a better, more stable light source to image less-sensitive plates. The reason is that the violet lasers (the key component of the imaging head) are now available as solid-state diodes rather than the volatile gas-driven visible-light lasers that had previously been used in imaging applications. These diodes are also much less costly to produce, making the entire device cheaper to manufacture and thus, easier to purchase.
While both visible-light and thermal technologies will expose plates, thermal retains its edge in plate imaging integrity and currently remains the only practical way for a printer to reliably differentiate through higher-fidelity presswork (e.g. using high-line AM or stochastic screening) or to adopt processless plates in the future. In a highly competitive market, the combination of cost savings, increased profit potential, and future upgrade capability are the reasons for the continued popularity and growth of thermal technology.
In June 1995—shortly after Creo (in partnership with Kodak) introduced the first truly viable thermal infrared imaging CTP system as an alternative to visible-light systems—the Seybold Report on Publishing System forecast, “Thermal plate technology appears to offer many attractions to printers… Many experts see the thermal plate as the plate of the future.” The market response was immediate and thermal technology quickly outpaced visible light CTP sales. More than ten years later, thermal imaging is still the technology of choice, despite the acceptance of some violet-light imaging devices.
What about the processless plate making “revolution”?
Anyone following the print industry understands the value being offered through “processless” printing plates, especially to smaller printers. Recently, some manufacturers have announced and started early production of violet “Chemistry Free” plates. However, only thermal can deliver true non process plates where no post-imaging treatment or washing equipment is required before putting the plates on press. This is because visible light plates (such as violet) are by definition sensitive to light, and cannot be handled in a normal pressroom environment unless the non-exposed coating is removed in a wash or processing unit first. “Chemistry Free” is also a misnomer, because chemicals are still used in the washing of those plates after imaging—requiring proper chemical storage, handling, cleaning, and disposal procedures.
Non process thermal plates are available today. In 2004, Kodak Polychrome Graphics introduced their first true non process plate, the THERMAL DIRECT Plate, which requires absolutely no post-imaging treatment before being put on press. This plate is now in production and is helping many hundreds of printers globally improve the efficiencies and profitability of their businesses.
Printers who have invested in Kodak’s thermal CTP devices are, in most cases, able to switch to thermal non process plates whenever it makes economic sense for them to do so. The lower initial cost of violet devices makes them attractive in a price-conscious market, and violet CTP devices are heavily marketed to small printers. Those who invest in violet systems may pay a lower device price today but will not be able to totally eliminate the processing steps and associated maintenance, chemistry and disposal (including “wash out solution,” which is chemistry) and running costs.
However, the device cost is only one of the factors to consider when deciding on a CTP solution. Making a wise business decision in an increasingly competitive market is challenging, and should not be based on device price alone. For printers considering CTP, a Total Cost of Ownership (TCO) calculation can clarify the true long-term costs and advantages of various options, and contribute to an informed purchase decision. When choosing a CTP system, business owners should consider the purchase in terms of these factors:
However, the device cost is only one of the factors to consider when deciding on a CTP solution. Making a wise business decision in an increasingly competitive market is challenging, and should not be based on device price alone. For printers considering CTP, a Total Cost of Ownership (TCO) calculation can clarify the true long-term costs and advantages of various options, and contribute to an informed purchase decision. When choosing a CTP system, business owners should consider the purchase in terms of these factors:
1. Initial costs (equipment, space considerations, installation)
2. Service costs (and how to minimize them)
3. Materials costs and savings in prepress and on press
4. Labor savings
5. Potential increases in revenue
1. Initial Costs
Add the costs for the CTP device(s), the associated software and hardware, the space requirements and environmental preparation. This is only the starting point for a TCO analysis—ongoing costs and savings are far more important. In the initial costs, considerations should include:
CTP Device(s): How reliable is the device, and what is its proven track record? Will a redundant CTP device be required?
Workstations and software: What are the options to drive the CTP device? Is a workstation from the same supplier required, or can any workstation be used, together with a generic interface to drive the device?
Space and architectural costs: How large is the CTP system footprint? Does it require a clean, climate-controlled environment? Will a darkroom or other light-proof handling be required? Will it require processing equipment?
Installation costs including downtime costs: How long will operations be disrupted during installation?
2. Service Costs
For any printer, reliability is paramount. To minimize the risk of downtime, it is important to consider the requirements for service and ways to minimize unexpected costs:
Service contract costs: Once the cost of a service contract—over a specified period of time—is added to the cost of the CTP device, the price differential between brands and technologies may diminish.
Warranty coverage: All devices come with a warranty of some kind, but does the warranty cover the most costly parts, or the parts that are most essential to plate making?
Speed of service: A warranty or service contract is only as good as the speed of service. Can the system be diagnosed and/or serviced remotely to get you running again quickly should a problem occur?
Equipment design that minimizes downtime: Does the CTP device require frequent calibration? Non-productive time is costly, even when it can be scheduled into off-peak hours: the device must be stopped and someone must perform the calibration.
Are critical parts designed for non-stop production? Does servicing require an onsite visit? Kodak laser heads feature a redundant design, so that production continues at full speed even if individual lasers fail. A service call can thus be scheduled when convenient for the customer.
3. Materials costs and savings
Many CTP conversions are cost-justified by material savings in prepress and on press:
Material savings in prepress: CTP eliminates all the costs of film and film processing, but CTP plates are slightly more expensive than film-based plates. Note that the cost per plate should include the cost of any required chemistry (including additional disposal costs). Are film-related savings alone enough to cost-justify a CTP installation?
Disposal costs of prepress chemicals: Except for non process plate making, all plate making involves chemicals that must be disposed of in an environmentally sound manner, and disposal costs must be considered. Some violet-light CTP processes rely on silver, an environmentally-unfriendly heavy metal that can be very expensive in terms of disposal.
Material savings on press: Paper spoilage is a major cost factor. Will the CTP system under consideration help reduce makeready time and paper volume used? Are there any ink-savings that can be expected and quantified?
4. Labor savings
Labor costs are a major expense. Kodak’s thermal CTP is a highly-automated process that eliminates film and its associated handling and inspection, as well as the handwork of handling, processing, and punching conventional plates. Can staff be reduced or re-deployed as a result of the CTP installation? Is the system intuitive enough that existing staff be retrained to operate it, or would new staff with a specific skill set need to be hired?
5. Potential increased revenue
Prepress and press departments typically don’t have the same perspective as the print customer and may not realize the potential customer and sales impact of the CTP investment. Print buyers are driving printers’ adoption of FM/ stochastic screening to achieve higher fidelity, more consistent, artifact free reproduction of their jobs. The finer the screening, however, the greater the demand placed on the integrity of the plate imaging system. The same process variations that prevented film-based plating from delivering these types of screens in the past still exist with violet CTP systems today. Another reason that printers re adopting FM screening is that it enables the effective use of inkjet contract proofing since there is no longer a need to proof for AM/XM screening artifacts such as moiré.
Making the choice
While the debate over thermal and violet CTP continues, the really important decisions that customers face are about what will yield the greatest ROI when all costs and potential value are factored in. If market acceptance is considered, thermal is still the choice of the great majority of the industry in all print segments, largely because it offers unparalleled stability, accuracy, consistency, overall economy, and ultimate ROI. If the future of the industry, and more importantly the printer’s business, is considered, thermal offers the greater adaptability and flexibility, opens the door to non-process plate making, and unlocks the full potential of a CTP investment.