The new method reduced the dark staining produced on the thermosensitive surfaces of thermal paper (commonly used for bills and receipts and thus important in fingerprint detection) treated with DFO or ninhydrin petroleum ether (NPB) solution, which minimizes the contrast between the developed fingerprints and the background. Reducing the dark staining did not remove the thermosensitive layer and parts of the developed fingerprints, such as occurs with acetone washing. Under the new method, the developed fingerprints appeared in sharp lines and high contrast. The extensive testing led to an optimized working solution that charges the paper with a minimum of chemicals. Further, it is inexpensive and allows a large quantity of paper to be treated in a short time. The working solution contains commercially available, nonvolatile, nitrogenous organic compounds and can be used by dipping. The optimized solution called "G3" consisted of 1.85 g of 4-pyrrolidino-pyridine, 1.59 g of oenantholactam, 2.47 g of 1-octyl-2-pyrrolidone, and 2.10g of 1-cyclohexyl-pyrrolidone. These components were mixed and dissolved in ethyl alcohol until a homogenous, clear solution was achieved. The solution was filled up to 1000 mL with petroleum ether. One liter of solution was projected for more than 6 square meters of thermal paper. 1 table, 6 figures, and 7 references