Coating Key to Digital Durability

One capability printers require to capitalize on short-run, on-demand printing is coating. For offset presses, coating provides dry delivery, ready to finish. For digital, where Web-to-print and variable-data front ends capture much of the limelight, finishing systems are at least as important-coating in particular.

Not only does coating enable the printer to deliver a cut, collated, folded and bound job, it adds value by capturing the recipient's attention, with a latent benefit being protection from finish-line scuffing, weather and the U.S. Postal Service sorters.

While offset presses can easily be configured with coating units, digital presses are limited to applying toners. As a non-impact form of printing, toners don't adhere as well to substrates as do offset inks and are more vulnerable to cracking during the folding process, as well as scuffing and scratching as they are sent through the mail stream.

Digital print engine suppliers have created solutions—Kodak's NexGlosser and Xeikon's PrintProtector. Now there are three offline suppliers—PAT Technology, Kompac and Olec Corp.—that have developed liquid coating solutions. Olec's DMC series coaters are built around an off-line UV coating system that complements conventional offset as well as digital presses and even wide-format printers. Available in four model sizes—from 19×25.5´´, 30×30,´´ 40×40´´ and 65×80´´, with optional larger sizes—the DMC use a roller coating process to put a protective sheen on the printed sheet, with applications in direct mail, tags and labels, collateral, book covers and wide-format posters.

Olec's DMC 19 is intended for dry-toner presses such as the Canon imagePRESS, HP Indigo, Kodak NexPress and Xerox iGen 3, as well as two-page direct imaging offset presses such as the Presstek-based Ryobi systems and the Heidelberg Quickmaster DIs. In the event volume demands it, the DMC can also be configured to run inline with most digital presses, though that limits speed and paper options.

For off-line operation, the DMC series can be configured for either manual or automatic feeding, using a hybrid friction rear pick-up feeder. The system accepts any paper weighing 80-lb.(text) or heavier, and operators can vary the coating thickness using a precision metering adjustment. In terms of maximum throughput, the automatic version can feed up to 4,000 12×18´´ sph.

Either gloss, satin or custom finishes the printed piece, flood coating only—there is currently no opportunity for applying a spot coating.

A combination of infrared and/or UV curing is used, with varying dwell time, depending on the formulation of the toner being covered—each manufacturer's toner formulation creates different requirements.www.olec.com