Stealing the CTP Scene?

Flexo printers can achieve outstanding results using patented screening techniques and imagesetter calibration.

By Terri McConnell

Flexo packaging printers have long been fighting the war on dot gain. Depending on the process variables (dot shape, plate material, substrate, inks, etc.), a 2 percent screen dot on a conventional film or plate could gain to around 15 percent on press. If not adequately compensated for, this characteristic can severely limit flexo's ability to reproduce a full, rich color gamut with brilliant, detailed highlights and clean open reverse areas.

The new photopolymer computer-to-plate technologies have certainly put an edge on flexo quality by conquering the dot gain menace. A good deal of space in this column has been devoted to explaining how CTP can reduce, even eliminate, the effects of dot gain. But CTP quality comes at a high price. The total investment for imaging and processing systems can easily hit the half-million-dollar mark.

What about the trade shops, printers, and converters who can't justify the capital equipment costs of CTP? Since it was introduced just a few years ago, more than 200 companies that produce flexo plates have opted for a CTP alternative called FlexoCal. The system was developed by PCC Artwork Systems, a well-known packaging front-end system provider. According to Mike Rottenborn, North American product manager, "FlexoCal is an imagesetter calibration technique which allows flexo trade shops and converters to approximate digital plate quality with their existing film-based assets."

The FlexoCal program is most often used in conjunction with PCC's Hybrid Screening, a program that combines conventional and stochastic screen patterns. Both are available as software modules on PCC raster image processors (RIPs), such as the Nexus. Formally introduced at DRUPA in May, Nexus controls step and repeat functions, screening applications, and the general flow of prepress image data to existing proofers and film output devices.