When ink is printed on paper a part of the ink is partially absorbed by the paper. For the offset process this property is very important. If the ink is absorbed too slowly or too fast, it may result in a change of the dry ink properties. An absorption, which is too slow, may result in e.g. smearing because the ink does not dry fast enough. An absorption, which is too fast, may result in a reduction of e.g. gloss; in this case the absorption of the ratio of binding agent and pigments has been changed.
The printing form is covered with coated rubber of a hardness of 85 Shore A. Often this method is used as a quality control test. To test inks, the method can be executed in the same way, but instead of a test ink the ink to be tested is used together with a standard paper as APCO II/II, IGT code Ka.
A paper strip to be tested is printed with a standard gloss ink with the help of a printability tester. After drying the ink, the gloss is measured.
Method of operation
• It is recommended to execute the test in the standard atmosphere; to most standards it is 23.0 ± 1.0 °C (73.4 ± 1.8 °F) and 50 ± 2% rh.
• For the operation of the AIC2-5T2000, Global Standard Tester, High Speed Inking Unit 4 and ink pipette follow the instructions of the manuals, IGT information leaflet W100 and the displays accurately.
• Handle the samples carefully.