Thermal desorption and GC-MS--which was initially developed for the direct analysis of solvents, additives, and resins in writing ink on paper--was successfully applied to ink dating. The study proved by evolved gas analysis that the extent of evaporation of solvent from an ink sample on paper at a certain low temperature is age dependent. This leads to the conclusion that the solvent content in an ink sample on paper can be divided into different fractions, which vary in the temperature required for their effective evaporation. The proposed aging procedure is based on measurements of the change of a relative value within a certain time frame; it is therefore independent of sample amount and the analytical instrumentation. Casework confirmed that this dating procedure of ballpoint ink on paper can be applied to ink entries with a maximum age of several months. The results of this study, in combination with the information about the chemical composition of each of the tested inks, indicate that the aging behavior of a ballpoint ink depends on the type of binder resin in the ink composition; however, the dependence of the absolute values of the measured parameter on the type of paper indicates that the composition of the paper also influences the aging of some inks. The usefulness of the described method was shown by analyzing over 300 different ballpoint inks chosen randomly from a reference collection at the Forensic Science Institute of the Bavarian State Bureau of Investigation and grouping them into solvent and binder resin classes. 3 tables, 6 figures, and 13 references