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Summary:
It was recently demonstrated that a thermogravimetric analyzer could be modified to model the function of a web offset heatset drying oven (1) Given that this technique could be potentially very useful, a study was made of some of the variables that may be important in solvent retention. The effect of these variables on solvent retention was examined. Some of the variables studied included heating rate, final temperature, solvent composition, ink color, and resin composition. The data collected to date indicates very little dependence of solvent loss on heating rate. This was surprising and possible explanations are currently being investigated. A dependence of solvent loss on final temperature is indicated. Solvent composition also has an effect on solvent retention. Studies on ink containing soybean oil show a large effect on solvent evaporation. An effect is also observed with high boiling hydrocarbon distillate cuts. Solvent retention shows very little if any dependence on ink color. Other variables which will be studied include amount of emulsified water, type of paper on which the ink is printed, and the effect of oxidation of the ink film.