After a six-month intensive production trial period one of the world’s oldest printers, Ziegler Druck in Switzerland, has changed completely to use only conventional offset plates on its CTP unit
Never since Johannes Ziegler founded his printing shop 218 years ago had the company grown as fast as the years between 1997 and 2007, during which period three 16-pageMAN Rotoman web offset presses were added to an older 8-page MAN Octoman. In the year 2000 the strongly increasing demand for printing plates forced the Technical Manager Pedro Schmidt to a digital plate production with two platesetters using silver halogen plates. But the company found the very high light sensitive plates were also very delicate to handle during the manufacturing process.After the amortisation period Schmidt changed to the much more stable and less delicate thermal technology and installed in 2005 two Lüscher XPose! 130 platesetters with register punch and two plate-handling systems, one for each platesetter. While he appreciated the reliability of the Lüscher’s platesetter design, the high press runs and the ruggedness of thermal plates, he would not accept the longer imaging time. By then Lüscher had already started to develop the 200er series and both parties agreed that they would change to the faster 230 models when they became available. When this was the case in December 2006, Lüscher had already developed the UV Conventional technology, which was even faster and allowed the use of the less expensive conventional plates. Pedro Schmidt therefore decided to wait once again and test the new conventional plates.
Long trial
The first XPose! 230 UV was delivered in May 2007. Ziegler’s prepress team had developed a detailed benchmark test to evaluate during a six month period whether the change to conventional plates would create any negative effects. For the validation they had developed a detailed form, in which the employees of the CTP and press department had to judge for any
printing job whether the conventional Kodak Capricorn Excel plate would be better or not as good as the Kodak Electra Excel HRO thermal plate. Both plates have always been burned in after development since press runs up to a million and more are common.
Imaging inspections
The platesetter operators had to check whether the CTP control strips were imaged correctly, whether aluminum swarfs would create a halo in an image, whether the visibility of the latent picture was better or less good, whether fingerprints would become visible before development or after burning, how fast the contamination of the developer rose and how consistent the readings on the plates were. The result was, that no substantial differences between both plate types were found.
Print inspections
At the web presses the printers had to answer several questions and to mark one of three given answers: better, about the same or inferior. They had to judge how fast the plates were in colour at print start, the water/ink balance during printing,
ink supply during printing, how fast the plates were in colour after blanket cleaning, the reaction to the colour calibration by the Instrument Flight, the amount of plate cracks and the plate handling sensitivity. The total of all answers showed that the behavior of both plates was more or less the same.
This was the confirmation that the change from thermal to conventional plates would not have any disadvantages, that the change could be completed and that a second XPose! 230 UV could be ordered. With the installation in November 2007 the complete plate production changed to conventional plates and the period of more expensive thermal plates ended.
