Ed #11 Print It

In all of their many variations, modern commercial printing presses are marvelous machines. Many have more computing power than was used to land a person on the moon. They can print more colors than Gutenberg ever dreamed of and run faster than a Kentucky Derby winner. And when your job is on press, all of this technology—and the highly skilled employees who run it—is yours to command.

The challenge, the satisfaction and, some might even say, the thrill, is to use all of a modern press’s capabilities efficiently, cost effectively and with maximum impact. And doing so begins with understanding how presses work.

The vast majority of all commercial printing is produced using two main types of equipment: conventional offset lithographic presses and digital presses.

For close to a century, the most common printing technology has been offset lithography, which is based on the simple idea that oil and water don’t mix. Oily ink is applied to the area of the printing plate that contains type or images and is kept from the non-image areas by a thin film of water or a dampening solution. Some offset presses are equipped for waterless printing in which specially formulated inks are repelled from the non-image areas by a coating of silicone.

Offset printing, is so named because the image is not applied directly from the printing plate to the paper. Instead, the image is transferred from the inked plate to a rubber blanket, and the blanket, not the plate, prints the image.

Offset printing offers a number of advantages over direct methods. The surface of the rubber blanket can conform to the paper more readily than the plate itself, so less pressure and ink are required, and the plate lasts longer since it is not being abraded by the paper. What’s more, the image on the plate does not need to be reversed as it does when the image is printed directly.