Offset Printing Symposium

Lectures and a chance to talk shop and gain new experiences were in the offing when ContiTech Elastomer Coatings invited experts from the printing sector to the Northeim plant for the CONTI-AIR® symposium on Heatset Web Offset Printing. In their lectures, renowned specialists dealt with possibilities for further improving printing results in the offset process.

Dr. Jochen Gattermeyer from Sun Chemical Eurolab opened the series of lectures with a talk on the topic of “Mechanical Ghosting“, a relatively new problem in web offset printing that occurs in halftone areas in parts where there is greater ink coverage on the reverse side. After numerous rotations the areas with greater ink coverage become visible in the halftone area, producing a darker, more intensive image definition. According to Gattermeyer, rubber blankets with poor "quick release“ properties abet the problem. In his lecture he presented what is known so far about the causes of this phenomenon and indicated solutions to the problem.

Falk Hübner from the Paul Sauer Walzenfabrik in Berlin gave a talk on “Dampening Roller Covers in Alcohol-Free Heatset Printing” and pointed to the influence of the roller cover composition on the printing result. Graphs showing the dynamic and chemical properties were used to illustrate points in the lecture, in which the interaction of solvents and inks with the roller covers was also discussed.

Rob Berndsen and Harry Zwiers from Senefelder Misset, a company in the Roto Smeets de Boer Group, spoke about the "Results of Inline Density Measurements on Double Printing Units". This talk dealt with increases in tonal values on the top and bottom sides of the web and on different printing machines. Berndsen advocated regular adaptation of the correction curves to the printing results. This is, he said, the only way to arrive at comparable results and to achieve reproducible control of the machines.

Jan Jungmann from ContiTech Elastomer Coatings addressed the topic of "Conveying Properties and Cover Stock Polarities of Rubber Blankets“ and in this context also touched on the manufacture of a rubber blanket. The audience was also told what impact a printing blanket has as far as minimizing the effects of mechanical ghosting is concerned and why the conveyor properties of the rubber blanket play a key role in this regard.

E-mail requests for any of the talks delivered at the symposium can be sent to jutta.freter@ec.contitech.de.

To wrap up the day, those in attendance were invited to tour CONTI-AIR® production at the Northeim plant, where they were informed as to the peculiarities of rubber belt manufacturing.  A golf tournament the following day at the Hardenberg Golf Club in nearby Levershausen rounded off the event.