A study of Toray\u27s negative working driographic printing plate and the effect ink tack has on toning in the non-image area

Driography is a planographic printing process. A driographic printing plate differs from a conventional offset lithographic plate in that water is not required to keep the non-image area clean of ink during printing. Water, or fountain solution, is not required during printing because a silicone rubber coating which repels ink is used for the non-image area of a driographic plate. The first driographic plate was introduced in the early 1970\u27s by the 3M Company. The plate was a positive working printing plate and has since been discontinued. Driography has since been researched by a number of companies but only one is presently marketing a driographic plate. The Toray Company, a Japanese based firm, is producing a negative working driographic printing plate. The purpose of this study is to research Toray\u27s negative working driographic printing plate. It is hypothesized that as ink tack decreases, toning in the non-image area will increase. In this experiment, ink tack was monitored at the point of impression using a thermocouple device. The thermocouple was used to measure ink temperature on an inking form roller. Temperature/tack curves were developed and used to convert ink temperatures to tack readings. The actual experiment was performed on a duplicator offset printing press. A second technique using ink tack-reducer to alter ink tack was performed as an alternative test to support the initial method results.During the course of the study a number of variables could have altered the test results. These variables were monitored and kept constant during testing. The variable which affected test results most dramatically was the oil content in the ink. It was concluded that the amount of oil content in an ink had more influence on the degree of toning than ink tack did as originally hypothesized