pointed out hereinafter a typical fusing system e g electrostatographic printing system includes a fuser roll a pressure roll a printing medium an image a metering roll a donor roll a release agent sump and a fuser fluid or fuser release oil in this example the fuser fluid is treated with a fluorescent tag an ultraviolet lamp is radiated onto the fluorescent tagged fuser fluid in the sump and fluorescence intensity is measured as a function of wavelength the measured fluorescence spectrum is then fit to a model in which the model parameters are compared with predetermined values for example predetermined wavelengths stored in a fluorescence detection device the fuser fluid is authenticated if the model parameters meet the stored values as the model parameters are dependent on the location of the detection for example where in the fusing system the tested fuser fluid is obtained from and thereby the parameters are dependent on the amount and temperature of the fuser fluid a typical solid ink jet sij printing system includes a drum maintenance and imaging cycle an image on the drum surface is transfixed to a sheet of final substrate by passage through the transfix nip the drum maintenance roller then cleans and applied drum maintenance fluid to the drum.