Author/Authors :
KESKİN, Bekir Gazi Üniversitesi - Teknik Eğitim Fakültesi, Turkey , TUTAK, Doğan Gazi Üniversitesi - Teknik Eğitim Fakültesi, Turkey , KÖSE, Erdoğan Marmara Üniversitesi - Teknik Eğitim Fakültesi, Turkey
Abstract :
Offset printing system is widely used in the sector. In offset printing, the main factor providing quality is the ability to print with a high dot frequency. In the transfusion of the image to the print material, dots must be transferred in the correct way. However, in high circulation jobs, problems arise in the transfusion of dot to print material. In this study, with the aim of finding a solution to the problems mentioned, aluminum carrier, a light sensitive fabricated emulsion offset plate was exposured with UGRA-82 test scale. During the printing process, fountain solution’s different pH degree values were (pH-1,5, 3,0, 4,5, 5,5) regulated. Printing continued for 12 hours, 3 hours for each print, at a print speed of 5000 sheet/h. During the printing process, the pH value of the fountain solution was changed every 3hour. Print samples’ 20%, 50%, 70% and 90% dot values were being measured at the 10. 20. 30. 40. 50. 60. 90. 120. 150. and 180th minutes and relationship between the pH value of the fountain solution and dot values were analysed. When evaluating the tests carried out, it is concluded that dot losses are effected as the fountain solution pH falls to acidic values. Consequently, pH of the fountain solution must be kept constant between pH 4,5 - 5,5.
