If you know anything thing about printing in the last 5 years, it’s probably this: the two main ways to get an image on paper are with either a digital or an offset press. As a customer, you’re not likely to be asked which type you’d prefer—and you’d be forgiven for not knowing these two options even existed. But because we think it’s helpful to be informed, we wanted to share a little behind-the-scenes look at how offset and digital printing work—and why we think they’re both worth keeping around.
It begins with the creation of custom polyester or metal plates. The image to be printed is transferred to the plate by exposing the plate to a high intensity laser, which burns the image to be printed onto the plate. Plates are created for each color to be printed, either spot colors or the primary process colors cyan, magenta, yellow, and black or varnish. Then, each plate gets attached to a separate set of rollers and blankets within the printing press.
Next, the press applies first moisture then ink to the plates (the ink sticks to the areas exposed by the laser). As the plate cylinder rotates, it transfers ink to a rubber coated blanket cylinder, which in turn transfers the ink onto paper. This might seem like a slow cycle—but it actually happens lightning-fast. Our 5-color Heidelberg offset press can lay down all four process colors, plus a fifth spot color, in a single pass—and can crank out as many as 12,000 impressions per hour.
Offset printing is best suited to longer runs (because of the cost of creating plates, shorter runs are typically less cost-effective). If a job is more than 500 pieces, offset printing usually is best. We have a wide range of specialty paper stocks, finishes, and varnishes we can use to customize offset prints. And the results are spectacular.
Digital presses, on the other hand, are a little bit different, they will take the electronic image directly to the print engine skipping the whole plate process. Like the offset press, all four colors can be transferred to the paper at once, but instead of using plates and rollers transferring ink to the blanket cylinders in a fixed pattern, digital printers interpret “bit maps” directly from image files. Then a laser beam exposes areas of a drum or belt, equipped with photoreceptors, which act as a magnet for colored toners. The toner is then transferred to the paper, and sealed in place with heat. Another thing about digital printing is that colors are built with the 4 process colors, not spot colors so that in the end, you are either printing black and white or color.
The chemistry of toners and inks mean that not all papers work for digital printing. But digital is perfect for short runs, because you can print the exact number of copies you need at a fixed cost—including large-format pieces. And a huge advantage of digital is the ability to use variable data, images are re-created for each sheet printed. Names, addresses, and even personalized images and messages can be programmed into a digital printer—great news for those interested in direct mail.
And digital’s quality has improved greatly in the past 5 years. Oregon’s Ricoh C901 and Xerox 700 digital presses can deliver impressions almost indistinguishable from offset work.
Why we need both
But in terms of quality, paper processing, and finishing effects, there are some aspects of offset that digital can’t touch yet. These days, it’s not uncommon for us to use digital and offset presses in tandem for a single job. For example, we might use the offset press to print several hundred or even thousand copies of a mailer, even adding speciality varnishes, then run it through the digital press to add variable data.
We think it’s important that the two sides of our print shop work closely together. Investing in both digital and offset presses means we can take advantage of what each machine does best. Of course, this requires advance planning and attention to detail on our staff’s part. Paper has to be used correctly, processes must be timed precisely, and everyone has to understand the presses well enough to know what we’re capable of.
Many of our clients may never see the steps that go into producing their business cards, mailers, or brochures. But that’s okay. We know by their faces when they see a great-looking new piece that the extra work is worth it.
Want to know more about how the print process works? Get in touch with Oregon—we’re happy to share what we know.