Printing has changed more in the last 50 years than it has in the previous 200-and with each change, there are new opportunities and challenges. Let’s look at the evolution of the digital printing era, some of the challenges faced, the opportunities it has created and where we are today.
With film, we refined what we were doing to the point where we could print some high-quality images with resolutions of 200 – 300 LPI. We had good proofs that accurately represented what was expected on the printed sheet. Then, we moved into the digital era that opened up many new doors.
Some new companies emerged on the scene that were not printers, but were computer savvy and saw great opportunities in the printing trade. Creo and Presstek were a couple of the more notable ones. These companies worked on being able to take the digital image from the computer and accurately transfer it to a plate (CTP) without the need for film. They also transferred information from the computer directly to the press (DI).
In the beginning, they worked with a “spark technology” that gave us an image that didn’t have the sharp, clean dots and nice rosettes that we were accustomed to with film. Instead, the dot was rather splattered and had fuzzy edges to it.On the upside, we had pleasing colour, which was fine for some work, and we had eliminated film, which was both a time saver (no stripping required) and money saver (the cost of film). It also gave us the ability to make changes in copy at the last minute and still deliver the job on time (instant four-colour process printing). We soon changed from the spark technology to laser technology, which gave us a much sharper and cleaner dot on the plate.
COMPARING CTP DEVICES
At this point, the plate manufacturers were working hard to make good plates that worked well with the CTP technology. In the beginning, the CTP plates were expensive and sensitive to external conditions. If everything wasn’t right in the imaging and processing stage, you’d have many problems on the press.
Two types of plates and platesetters (CTP devices) emerged here-thermal plates that aren’t light sensitive and are imaged with IR radiation at 830nm with an external drum device, and the light-sensitive photopolymer and silver halide plates, which are imaged with an internal drum device. The photopolymer violet plates are imaged at 400 – 410nm and the silver halide at 488 – 532nm.
The advantages of the thermal plates included a good, sharp, stable dot with a tonal value change less than 0.5% during running. Because of its stability, it’s a good plate for FM (Stochastic) screening and it will usually give you longer runs. The main advantage of the violet plates is the cost-they’re less expensive than thermal plates.The dot on these plates is not as sharp as thermal plates and noticeable sharpening of the dot and tonal value changes are apparent the longer the run is. This plate has a tonal value change of more than 1% and is, therefore, not compatible with FM screening. The silver halide plates are very dirty to work with and are also high maintenance.
At the same time, technology was changing quickly in the prepress area as there were both challenges and great opportunities in the creation and manipulation of images. Companies like Corel, Quark and Adobe were leading the way here. Some of the early challenges were banding in vignettes and moirés, especially in flesh tones and rough edges on letters and images. These have long since been resolved by changing dot shapes, image resolution and in some cases, screen angles.
ACCURATE PROOFING AND PRINT COLOUR MANAGEMENT
Once we were able to do away with film, a whole new problem came about. Those good, accurate proofs we used to produce were made from film, so we could no longer give the customer an accurate proof; also the press operator didn’t know what the job would look like. He/she would sometimes have an original or previous copy to check against, but there is less dot gain with CTP than with film, so he/she would try to do colour correction on the press to match the previous copy. The problem was, the operator didn’t have a hope of being accurate.
So,we had to find a way of using this digital information to create accurate proofs.
The first reasonable digital proof was the Iris. It gave us a good idea of what could be expected on the press, although it had a very light blue screen throughout the background and wasn’t as accurate as we had become accustomed to with film.
Better software programs were developed where ICC profiles could be put in place for output to better printers. (HP and Epson are the dominant ones at the moment). Many of these ICC profiles were “canned” profiles that didn’t match the conditions of the print shop, or work in the same colour space as the presses in that print shop.Any good, accurate proof has to work within the same colour space that the printing press is able to print, so print colour management is required to tie everything together. There are many steps to proper print colour management, and every device used in the production of a printed piece has to be hallmarked and calibrated to set standards. Identifying and documenting these standards is the first step.
The following should all be taken into consideration: CTP device, type of plates used, proofing device, type of proofing material, dot shape, line screening, AM or FM screening, press type and conditions, inks, paper, blankets, dampening solution, target densities, LAB, dot gain values (are they ISO, GRACoL or customer-defined standards?), measuring devices (densitometer, spectrophotometer) and device settings (status T, DIN 16535, D50, D65) and so on. Once this is done, the CTP and proofing devices can be calibrated to base standards through computer programs. An ink weight profile is set for the proofer and a linearization curve is applied to the platesetter. Measurable control elements should be put in place to assure these device settings have not changed. We next fingerprint the press by running a test form with linear plates to the defined inking standards. Once this is done, we can measure the elements of the test form and compare where we are in relation to our dot gain and grey field targets. Computer programs today will allow us to feed in this information and calculate what changes have to be made to hit our predefined targets. A process curve is then made to alter the image on the plate so that the printed sheet meets the target standards.
At this point, we can extract the colour space information from the test form to create an ICC profile. This digital information defining the colour space that our press is able to print in, is then put into the program that sends the information to the proofer. We now have our printing press and proofer working in the same colour space so we’re back to the point where the proof and the printed sheet match. We have a predictable result that both the printer and customer can rely on. This ICC profile can be sent to any agency, design house or anyone that can make proofs for you, so the result is always the same.
OTHER DIGITAL OPPORTUNITIES
We’re beginning to see more “soft proofing” (i.e., sending the customer the proof in a digital format to view it on a computer monitor. This is not quite as accurate as a “hard proof” because we’re transferring CMYK information to an RGB output. The important factors here are that your ICC profile is applied to the customer’s program and that the viewing conditions are controlled so one can view it properly).
Another opportunity that came from digital was the ability to create CIP3 (PPF) and CIP4 (JDF) files that have allowed us to communicate with and between all the devices in the print shop, prepress, press, post press and beyond. Digital image information is now used at the press to preset the ink fountains so that when a new job is put on the press, accurate colour to predetermined values is achieved in a minimal number of sheets.
There are also programs that will update compensation curves for this information as conditions change (i.e. different inks, paper etc., to keep the inking profile as close as possible to perfect when a new job is loaded. A full makeready on a large multi-colour press can now be done in less than half an hour).
Post press devices are also able to use this information for setup. There’s no longer a setup at the cutter for jobs with many cuts. What used to take days and weeks to produce is now produced almost instantly.Today, we can receive a job in the morning, and deliver it later that day. The important thing to remember here is that you have to set standards and calibrate everything to those standards to get a consistent and predictable result.
THE CHANGING WORLD OF PRESSROOM CHEMISTRY
If you believe that the printing industry has changed dramatically in the past 50 years, consider the fact that supporting industries must also change to facilitate the success of print shops today.
Pressroom chemistry is no exception. With the sophistication of printing presses, papers and other pressroom staples, has come a whole new set of problems relating to production-calcium carbonate, dot spread, linting, premature plate wear, pH and conductivity, problems with rollers, fountain solutions, and so on.
Over the past several years, pressroom chemical manufacturers have plotted a bold course of innovation through research and development breakthroughs. Each time a new problem developed in the pressroom, chemical manufacturers were there-not just with chemistry solutions, but with production solutions as well.
When I joined Commercial Litho Plate Graining in 1951, the shift to offset printing using aluminum plates as opposed to zinc plates was already underway. This was a major turning point in the industry at that time, so we devised a breakthrough processing method that made our company’s wipe-on plates the most successful in North America.
Today, chemical products for the pressroom number in the hundreds and include fountain solutions, alcohol replacements, plate cleaners, protective gums, solvents, silicone and other specialized products. They’re all formulated specifically to solve common problems that occur in the pressroom. With Unigraph International, for example, every one of our products is also pre-tested under carefully controlled conditions in our own manufacturing plant. They must meet the highest quality of the printing industry and cover every conceivable machine-sheetfed presses, heatset web presses, coldest newspaper web presses and so on. But, equally important these days is 24-hour technical support that helps printers reduce one of the costliest problems in the pressroom-downtime. To share this problem-solving expertise, field technicians must keep pace with virtually every emerging new technology in the industry. And this includes the ongoing realization that we must create products that make less of an impact on our environment; in other words, biodegradeable “green” products.
As the printing industry faces the challenging CTP and digital eras, pressroom chemical manufacturers will continue to be at the forefront of changes that reflect the rapid pace of our industry’s thirst for new technologies. Look at it this way: you might drive the most expensive, technically sophisticated car on the road, but see what happens when you start running out of motor oil for your engine or coolant for your radiator!
