Summary

This Special Report informs about a follow-up project to the project dealt with by IFRA Special Report 3.24, Better Newsinks or Better Newsprint to Reach Less Set-off. Whereas the first project used standard newsinks and optimal combinations with different types of newsprint from different manufacturers were discovered, the practical application of these findings was hampered by the fact that the compositions of the newsinks tested were unknown and, for competitive reasons, the various brands could only be published in an encoded manner. For this reason, it was decided to carry out a follow-up project at the same organisation, though this time model inks with a known composition replaced the standard newsinks. In addition, a new type of penetration measuring device was used. Three different grades of newsprint from the first project, with good, average, and poor penetration behaviour, were assessed in the follow-up project. In this way, it was possible to find a wide range of influencing factors, many of which interact in a highly complicated way. It is only possible to conclude that the rub-off behaviour gets worse with the higher structure of the carbon blacks, a larger share of the higher-viscosity soybean oil, a reduced resin content in the binding agent, and a higher printing speed. We hope that the clarification of these relationships will be of assistance to our members in helping to settle any disputes that may arise as the result of complaints, and that this Special Report will be well received.