The "Process Standard Offset Printing" (PSO) describes a standardised process for the production of printed products. This make it possible to assure the quality of the production process from the entering of the printing data to the finished end product. The respective audit checks whether the data handling, proofing, printing plate lighting and printing process (run set-up and printing) all comply with the standard. A set test print form is lit at the pre-stage and then printed.
"The certification audit that was carried out at the end of May focused on colour management and data handing monitoring processes at the pre-stage, and lighting processes (CTP) at the pre-stage. An OK sheet had to be printed according to the ISO/PSO specifications; certain colour spaces (LAB) as well as printing characteristics (tonal value increases) had to be achieved. After that, a run of 3,000 sheets was printed in the specified tolerances to the previously produced OK sheet. We used the new Heidelberg BO1 Speedmaster XL 106 ten colour perfector with coater for the certification process," says Guido Hochstrate, who works in the pre-stage technology and development area at Mohn Media and accompanied the certification process.
The PSO award tells customers that they can rely on a consistent and above all set data and printing quality. For many customers, the PSO certificate is therefore a criterion when they place printing orders. The Premium PSO certificate awarded this year specifies even tighter tolerances. They are lower than those of the "normal PSO" with regard to the tonal value increases, the tonal distribution and the solid colour of the primary printing colours K C M Y. Other specifications also have to be met; the solid colour of the secondary colours R G B and the tertiary colour grey. All specifications must strictly be consistently met during order set-up (OK sheet, deviation tolerances) and across the entire print run (fluctuation tolerances).