(Dead Tree Edition is pleased to welcome guest author Jack Graber, a member of Production Executive's Hall of Fame and most recently Director of Production and Corporate Paper for Redcats, a leading multi-catalog company. Although he's a catalog guy, even magazine people recognize him as the best in the business when it comes to figuring out whether rotogravure or offset, or both, are best for a particular print job. You can reach Jack at jlg500@aol.com. This is the first of a three-part series.)
Many publishers are overlooking a great opportunity to save money and improve print quality on the current crop of lightweight papers. That opportunity is rotogravure, one of the most misunderstood of the major printing processes.
Roto competes head to head with the more popular web-offset process for the production of high-volume catalogs and magazines. But previous rules of thumb about roto have misled many people, especially in
The popular rule of thumb is that it takes a print order of 1 million for roto to break even with offset, but in many cases it may make sense for much smaller press runs.
To understand the advantages of the process, we must first grasp the basics of rotogravure production. It’s an intaglio process, which means the image area is separated from the non image areas by being engraved below the surface – in this case into a smooth copper cylinder. Digital data for text and images feeds a machine known as a Helioklischograph, which does the engraving with diamond heads. The entire cylinder rotates in a bath of ink. As the cylinder turns, the excess ink is wiped off by a flexible steel doctor blade.
The paper is printed directly as it passes between the printing cylinder and the impression cylinder, with the impression cylinder containing an electric charge that causes the ink to be removed completely from the engraved cells.
The publication gravure press has the web going through the first four units, where only one side of the paper is printed at a time. Each color is dry before the next color is printed. The paper then travels up to be turned over and to have the second side printed. (In contrast, web offset prints both sides at the same time and does not dry one color completely before another is applied.)
The web of paper then goes through two folders – an upper folder to slit the larger web into what are known as ribbons and the lower folder to make the final signatures.
One advantage of gravure is the many options for sizes and page counts because both the cylinder circumference (or cutoff) and the web width can vary. For some of the high page-count magazine and catalog formats, you can print as many as 144 publication-size pages on the same press.
It costs more to start up a rotogravure press than an offset press, and it takes somewhat longer to make cylinders than offset plates. However the greater press capacity allows for less overall production time and the printing of less total forms for the bindery.
Next: Part 2, "Advantages of Rotogravure vs. Web Offset"
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