Nowadays, two different processes are used in web offset printing: heatset and coldset.
The coldset process is mostly used to print newspapers and paperbacks, with the printing ink drying purely by absorption.
In the heatset process, the paper is passed through a large dryer and a chill roll unit after the last printing unit. The length of the printing press is almost doubled by these two units. To ensure that the ink dries optimally, special heat-drying inks are used here.
The paper running through the printing machine at high speed is heated up in the dryer as the mineral oils contained in the printing ink only evaporate at around 200 degrees. The dry air that is blown onto the paper therefore has a temperature of around 250 degrees Celsius and heats not only the printing ink but also the paper to 100° to 120° Celsius. This process removes a great deal of moisture from the paper, as the water contained in the paper simply evaporates. As a result, difficulties such as the paper curling, bubbles or even static charging of the paper web arise. In addition, the resins in the printing ink become liquid, i.e. the ink becomes soft and sticky. Only when the ink is cooled in a flash at the end of the dryer by specially coated chill rolls does it become solid and acquire its characteristic heatset gloss.
The paper, which is very much affected by the heat, is moistened with a water-silicone mixture after the sudden cooling to 20° to 30° Celsius. The water moistens the paper, the silicone ensures that the print is scratch-resistant.
Papers used in heatset must therefore be highly resistant to heat, liquid loss, bubbles and swelling.
Due to the high energy consumption and stricter environmental regulations, heatset plants today are mainly operated with heat recovery systems.
Typical heatset colour profiles for printing and proofing are:
- PSO SNP Paper (ECI)
- ISONewspaper 26v4
Both are available on shop.proof.de as proof profiles.
A good video showing a heatset system can be found on youtube:
Heatset Video
You can also learn more about web offset on Wikipedia.
A few days ago Proof GmbH was the first company to be certified for proofing for the new 7C exchange colour space FOGRA55. Fogra has developed characterisation data for extended multicolour printing with the printing colours CMYKOGV – i.e. cyan, magenta, yellow, black (contrast), orange, green and violet – FOGRA55 as part of a research project over the past few years. The characterisation data and the ICC profile Ref-ECG-CMYKOGV_FOGRA55_TAC300.icc have been published on the Fogra website in recent weeks. We have now carried out the certification via GMG ColorProof, as … read more
RGB colour spaces are colour systems that represent different hues with the three primary colours red, green and blue. RGB colour spaces are used in digital image processing, photography and computer technology to precisely define colours. The most important RGB colour spaces and their special features are: sRGB sRGB is the most widely used RGB colour space and is used by most monitors, printers and digital cameras. It was developed by HP and Microsoft in the 1990s to create a standard for colour representation on the internet and on various … read more
This year we once again created proofs for Fogra certification and sent them to Munich-Aschheim for testing. With these proof prints, which we print according to three different proof standards and on three different papers, we point out that we not only deliver excellent proof quality through internal quality controls and checks, but that the quality of our proofs is also measured and confirmed by external experts. We have now had test prints certified by Fogra for the 12th time. We have also been “Spot-cert” certified for the display of … read more
After Eddy Hagen pointed out in this posts, that there were some major colour deviations between the brand new PANTONE Solid Coated Guide 2023 and the previous version especially for the PANTONE 2635 C, I was curious to lookup the same colours in the new PANTONE Color Bridge Coated Guide of 2023 and compare the colours with the previous version. I measured a dE00 of 8,15 between the two colours that Eddy mentioned, which is really far apart from how accurate PANTONE colours should match between the different PANTONE guides. … read more
The most important colour management event takes place every two years in Munich: the Fogra Colour Management Symposium. Once again this year, all professionals are invited to make the pilgrimage to Munich: two days of lectures, discussions and a Bavarian evening await participants. Matthias Betz, owner of proof.de, will also be there again: for many years, he has been taking advantage of the opportunity to exchange ideas with colleagues and friends, learn about new technologies, hardware and software, and talk to colleagues from Fogra, freieFarbe, GMG and many more. In … read more
A new generation of colour measuring devices is entering the market: in contrast to the classic measuring devices, which are available as a fully encapsulated system either as a colourimeter or as a spectrophotometer, and then supply the data to a computer via an interface or app or display it directly, the new generation of colour measuring devices consist only of lighting and software, with the optics of a modern iPhone from Apple being used as the sensor. Until now, there have been two categories of measuring devices on the … read more
Peter Jäger is an expert in colour management that reliably works across the boundaries of printers and monitors, web and print – essentially: cross-media.
In recent weeks, there have been lengthy discussions on the Fogra digital printing mailing list as to whether a research project should be launched to define standardised tonal value gradations for spot colours. What is this all about? In the field of CMYK and seven-colour printing, the definition of clear, printable and proofable standards is well established and has been tried and tested in practice. If the paper or paper class is known and defined, a measuring standard such as M0/M1/M2 has been established and the content of optical brighteners … read more
In the current issue of Fogra News “Fogra Aktuell” Proof GmbH is involved in two places. Firstly, a summary of the Fogra report on our first FOGRA55 certification for seven-colour printing with extended colour space in CMYKOGV appeared. You can also find more information on our FOGRA55 certification on the Fogra website: https://fogra.org/en/press-releases/fogracert-erste-cpc-zertifizierung-fuer-fogra55-cmykogv-330 and on proofing.de: And secondly, there was a report on the completion of the research project for textile digital printing, FOGRA58, in which we were allowed to investigate and test the proof capability of the new textile … read more
In recent years, various problems have arisen with our previous proof paper supplier. On the one hand, we sometimes had to wait more than three months for paper deliveries; on the other hand, we sometimes had significant problems with batch-to-batch discrepancies, surface defects and much more. After lengthy deliberations, we decided in December to replace all the paper. We therefore received pallets of new paper at the turn of the year, which we are now gradually incorporating into our production. There will be no hard cut, but the new papers … read more