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About two decades ago I was a custom printing consultant helping a client produce periodicals analyzing the actions of Congress in Washington, DC. It was a Friday night, and their flagship publication was on press at a local printer on a heatset web press. A tornado came in at that very moment and tore the roof off the commercial printing plant. When I called the sales rep, he said my client’s company was “on its own.” The job would not be printed and sent off to its paying customers that night.
So I contacted a local sheetfed printer I knew wanted the contract for this weekly magazine very, very badly. When I called the plant manager, who was at a bachelor party at the time, he agreed to be my client’s white knight. I sweetened the pot by noting that his successful completion of this job would probably create a vacuum that would suck all of my client’s jobs out of the web-press plant into his sheetfed custom printing plant.
He coordinated a new transfer of all digital data from my client’s office to his shop and produced the magazine via sheetfed lithography. Paying customers received a magazine that looked far better than prior issues. It came out on time as though nothing had happened. Within a year or so, the new printer was producing all of my client’s magazines.
Sheetfed vs. Web
The prior example might read like a fairy tale, but it’s actually true. That said, it was more expensive to print the magazine via sheetfed offset lithography than heatset-web offset lithography. Here are the differences and the reasons to choose one kind of press or the other for your own commercial printing work.
Both kinds of presses print via offset lithography, in which image areas on a flat custom printing plate are treated to receive ink, while non-image areas are treated to repel ink. When the press is running, ink is transferred from a printing plate to a rubber blanket and from the blanket to the paper (hence the term “offset”). So in this particular way, web presses and sheetfed presses are similar.
That said, paper is fed into a sheetfed press as individual sheets stacked in a pile at the front end of the press (even if they had initially come from a roll and had been cut into sheets). The sheets are pulled through all inking units, where they receive ink from the plates and blankets. Stacks of printed press sheets (printed on one side) exit the press and are stored for the ink to dry (via absorption into the paper and/or oxidation into the air, depending on the paper in use). Then the piles of press sheets are turned over and run through the press again to print the opposite side of the sheet (called “backing up the sheet”). Final printed sheets (printed both sides) are then brought into the finishing department for folding, trimming, and other post-press work.
In contrast, on a web offset press, paper comes from a roll. As the press runs, the ribbon of paper coming off the roll is held in tension as it enters the press. Like a sheetfed press, the web press uses plates and blankets on each inking unit to print the job.
If the paper is uncoated and the quality requirement is low (such as a newspaper or newspaper circular), the web press can be an open web (or non-heatset web). The ink dries through absorption only (ink seeps into the uncoated paper).
If, however, the paper is a coated press sheet (or roll, more accurately), the applied ink (usually four colors for this kind of work) has to be dried differently. So once the ribbon of printing paper from the web roll exits the printing units, it must enter the drying ovens, which flash off the solvent from the printed ink with intense heat (i.e., drying by oxidation rather than absorption), hardening the custom printing ink on the surface of the paper rather than letting it sink into the paper fibers. Then the ribbon of paper (the web) travels between the chill rollers, which bring the paper back to room temperature.
At this print, the web press can actually do some of the finishing work in line, getting the press signatures (in the case of my client’s magazines, for instance) ready for binding (some web presses do some kinds of binding in line as well).
Sheetfed presses can’t do this. (Finishing in this case is done in another department.)
Web presses are lightning fast. My random query on the internet notes that a sheetfed press can print 15,000 impressions per hour, while a web press can print 50,000 impressions per hour. (I don’t know how precise these numbers are, but the gist is that web presses are significantly faster than sheetfed presses.)
Moreover, a web press prints both sides of the roll of paper at one pass, unlike a sheetfed press. Either the ribbon of paper is turned over within the printing process using “turning bars” (with four of the inking units printing one side of the paper and then the other four inking units printing the opposite side), or press rollers, plates, and blankets above and below the web of printing paper print both sides simultaneously. This also speeds up the process dramatically.
But speed has its drawbacks. Even a heatset web press (as opposed to a non-heatset web press, which some people call a coldset web) cannot in most cases match the level of quality produced by highly skilled operators on a sheetfed offset press. (This is why my client’s customers who received the tornado edition of their magazine were knocked off their seats by its quality.)
In contrast, speed does yield cost savings. Sheetfed printing involves separate finishing operations in a different department, and overall it progresses more slowly, so the final bill is usually higher, depending on the total press run.
To illustrate, when I was an art director, my employer printed 60,000 copies of a 384-page (approximately) 6” x 9” perfect-bound print book (twelve 32-page signatures). The text was printed on a web press. I believe the 60,000 covers, since they were small, they could be ganged up on a single press plate, and they had to be of very high quality, were printed on a sheetfed press. I’m not good with math, but it seems to me that at 15,000 impressions per hour vs 50,000 impressions per hour, it would take much, much longer to print twelve 32-page press signatures (twelve separate press runs) on a sheetfed press than on a web offset press.
Why Choose One Press Over Another
If you’re buying printing and deciding what kind of printer to approach for a bid, here are some thoughts:
- If you’re producing a textbook, for instance, as was part of my job as an art director, consider the number of pages multiplied by the number of copies. In my case of 60,000 copies multiplied by 384 pages, that would be 23,040,000 book pages. In my experience, that’s definitely a web-offset commercial printing job.
- If you’re printing 60,000 copies of a 8.5” x 11” flyer that will be laid out (imposed) eight-up on a press sheet (eight final copies per 25” x 38” press sheet), then your final print run is actually only a fraction of the total or 7,500 copies, because out of every press sheet you get eight copies. That would most probably be a sheetfed job.
- Quality. Maybe you wouldn’t print an annual report on even a heatset web press. I wouldn’t. Even if it can run coated paper and four-color process ink work, it probably won’t look quite as dynamic as a sheetfed-printed annual report. However, if you’re producing flyers, forms, brochures, newspapers, newspaper circulars–either a heatset web press (for coated printing paper) or a non-heatset web press (for uncoated printing paper) might be a good bet. The key here is the length of the press run.
- So back to press runs. If you’re unsure, ask your printer. But my random check on the internet suggests 10,000 to 15,000 copies as a starting point for web offset, for magazines and brochures. While I would definitely agree with their assessment as it pertains to magazines (multiple custom printing press signatures multiplied by 10,000 or 15,000 copies), I think for brochures or any other work that can be ganged up on a press sheet, your target totals for choosing web offset lithography over sheetfed lithography would be much higher.
But it never hurts to ask your printer.
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