Many authors (3 to 10) have observed that the relative humidity and temperature greatly influenced the results obtained with ESDA. This study used an isothermally and hygrostatically controlled laboratory to test parameters independently to standardize and optimize the technique. Some of the ESDA trials were repeated several times on different days to check the reproducibility of the results, which constitutes the compilation of 300 tests altogether. Temperature was found to have little effect except on one type of paper and may, therefore, be ignored as a factor in most cases (laboratory temperature conditions are adequate). Relative humidity, on the other hand, must be controlled, since it drastically affects detection. An environment of 40 percent or 75 percent relative humidity are not satisfactory. The use of a humidifying chamber is also of little use if the detection is conducted under widely different, much dryer laboratory conditions. Sixty-five percent relative humidity for 1 hour was found to be optimal for 15 different papers tested, with the instrumentation also kept at 65 percent relative humidity. The document is maintained at 20 degrees C. and 65 percent humidity for 1 hour and processed under these conditions in a humidity-controlled room. The paper quickly adjusts to the environmental conditions. 3 figures and 12 references