Summary

During newspaper printing three different kinds of colour changes, making the end result deviate from a proof, can happen. A change between the proof and the average colour of the printed samples is caused by different processing methods and is called a colour deviation. A change in inking during printing causes differences in the printed results. This is called colour variation. A third possible source of colour differences are the different results from different printers who use identical originals. This deviation is most often caused by different hues of process colours and different ink- sequences. The changes originating from all these sources should, naturally, be minimised. During this project, carried out by EMPA/UGRA in Switzerland, we have measured the amount of variations and deviations in order to learn more about which processes and colour-combinations are the most sensitive ones. Also means to minimise variations and deviations have been studied. To do this, a colour strip of size 8 x 200 mm con- taining 25 different colour patches was printed by 9 printers on an editorial page of a production run. In order to offer also other newspapers a possibility to measure their printing process in terms of colour consistency, performance and adherence to standards and results achieved by other printers, IFRA has decided to provide the material needed for printing as well as service in measuring the printed samples through the IFRA Advisory Service.