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Jürgen Gemeinhardt

Jürgen Gemeinhardt

Head of department
Printing techniques

E-mail
gemeinhardt
transparent 11x15@fogra.org

Telephone
+49 89. 431 82 - 256

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Current research projects (in the field "conventional printing technologies")

34.021
Communication of characteristic values describing the metallic appearance of prints

Timescale: 01.11.2018 to 31.10.2020
Funding:
Programme of the Federal Ministry of Economic Affairs and Energy for the support of "Industrielle Gemeinschaftsforschung (IGF)" via the German Federation of Industrial Research Associations (AiF)

The goal of this research project is to establish objective characteristic values that correlate with the visual impression made by printed metallic surfaces. The aim is that it should be possible to measure these not just with specialist laboratory equipment but also by means of industry standard measurement devices and appropriate methods in support of production processes. It will allow metallic effects to be communicated simply by specifying target measurements in the same way as in standardized four-colour printing. Furthermore, the characteristic values should be scaled in such a way that they describe a perceptually uniform effects space. This should make it possible to specify aim values with sensible tolerances and to measure adherence to these values during quality control.
Existing approaches will also be built on in order to develop an appraisal technology that allows an unambiguous evaluation of the metallic effect. The focus here will be on determining various combinations of lighting and observation angles when using directed illumination. Practical recommendations will also be developed to enable users to carry out the best possible visual examination even without a dedicated viewing booth.

 

42.029
Laboratory method for the practical and reproducible determination of the residual strength of heat set web offset papers

Timescale: 01.04.2015 to 30.09.2017
Funding:
Programme of the Federal Ministry of Economic Affairs and Energy for the support of "Industrielle Gemeinschaftsforschung (IGF)" via the German Federation of Industrial Research Associations (AiF)

In heatset web offset printing a web of paper is fed through the press at high speed, running first through the printing units before reaching a hot air dryer in which the high boiling point mineral oils are evaporated from the inks. In the process, the papers are heated to well in excess of 100 °C losing a considerable quantity of water and becoming brittle.
The combination of this brittleness and the mechanical stresses during folding result in a significant reduction in the paper's strength and, if the residual strength is insufficient, the fold can break. If this is noticed during the production run all the printer can do is to attempt to counter it by reducing the printing speed or the hot air temperature. However, the problem is not usually noticed until it is too late and individual pages drop out of a finished, stapled or stitched printed product.
An existing laboratory method for determining the residual strength of heatset offset webs will be developed as part of the research project so that it reflects actual production printing condition. The new method should be accompanied by revised limits. In addition, the factors that influence laboratory results will be investigated in detail. This will allow specifications to be developed for the test procedure that ensure comparability with results from various different paper laboratories.



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